Guidance

MMRV vaccination: information for healthcare professionals

Published 28 November 2025

Applies to England

Introduction 

From 1 January 2026, all children will be offered the combined MMRV (measles, mumps, rubella and varicella) vaccine at 12 and 18 months of age. This adds protection against chickenpox to the existing provision of protection against measles, mumps, and rubella.

This guidance for healthcare professionals describes eligibility, administration and safety, and answers frequently asked questions about the new vaccination programme.

Background

Since 2009, the Joint Committee on Vaccination and Immunisation (JCVI) has been actively reviewing the latest evidence and considering vaccination strategies for protection against varicella and herpes zoster.

Whilst they considered both the possibility of a combined varicella (chickenpox) and herpes zoster (shingles) vaccination programme, a herpes zoster only vaccination programme was initially recommended. This was due to a concern that reduced chickenpox circulation following a varicella vaccination programme may reduce exogenous boosting (whereby re-exposure to varicella zoster virus boosts immunity and reduces the risk of reactivation), and lead to a significant increase in shingles in older adults. The shingles only vaccination programme was introduced in 2013 for adults aged 70 to 79 years and has undergone several changes since. It was agreed that this recommendation should be reviewed when further information relating to varicella epidemiology, vaccination and exogenous boosting was available.

The varicella zoster JCVI sub-committee met during 2022 and 2023 to review the updated evidence including:

• varicella disease burden
• potential impact on exogenous boosting
• seroprevalence data
• modelling cost-effectiveness and real-world data from countries who have already implemented a programme

This was then discussed by the main JCVI committee in their October 2023 meeting. The impact of chickenpox on quality of life was found to be significant. Modelling found a universal vaccination programme to be cost-effective. Previous concerns that a varicella vaccination programme would increase herpes zoster incidence (through lack of exogenous boosting) has not been found in countries such as the USA, who implemented a varicella vaccination programme in 1995.

In November 2023, the JCVI recommended a universal varicella vaccination programme be introduced into the routine childhood schedule. They recommended this should be a 2-dose programme offering vaccination at 12 and 18 months of age using the combined MMRV (measles, mumps, rubella and varicella) vaccine. They also advised that there should be a selective catch-up programme for older children without a history of chickenpox to help accelerate control and to further reduce transmission in the population.

From 1 January 2026, children due their first or second MMR vaccine from 1 January 2026 should now be offered a combined MMRV vaccine instead of MMR, and older children without a history of chickenpox will be offered a dose in a catch-up programme.

These changes are detailed below and in the joint UK Health Security Agency (UKHSA) and NHSE letter: The introduction of a routine varicella (MMRV) vaccination programme for children aged one year and 18 months, with catch-up to age 6 years in England.

Varicella (chickenpox)

Varicella (commonly known as chickenpox) is a highly contagious infectious disease caused by the varicella zoster virus. Infection is characterised by the presence of an itchy, spotty rash with fluid-filled spots appearing then blistering and scabbing over. Other typical symptoms of varicella that may appear one or two days before the rash develops include a fever, muscle aches and pains, and generally feeling unwell.

Varicella is very common and affects most individuals during childhood, although it can be caught for the first time at any age. It is transmitted through direct contact between people, or indirectly through airborne droplets. Individuals are infectious from up to 24 hours before the rash appears until spots have scabbed over, although evidence for transmission prior to rash onset is limited. Most varicella cases in children are relatively mild and the illness resolves without any need for treatment from a medical professional, though most children are unwell for several days and will miss 5 or more days from school or nursery. Parents may have to take time off work to care for them.

However, some children will go on to develop complications from varicella. These include bacterial infection of skin lesions, which accounts for 11% of complications among children admitted to hospital for varicella (1). In particular, varicella is a risk factor for invasive group A Streptococcal infection. Neurological complications include acute cerebellar ataxia (1 in 4,000 cases in children), and in rare cases, encephalitis (1 in 33,000 to 55,000 cases), pneumonitis and stroke (2). These complications can result in hospitalisation and very rarely may result in death.

Varicella is often more serious in very young infants (under 4 weeks); adults, in particular in pregnancy when it may cause complications in both the mother and the foetus; and in those who are immunosuppressed.

Measles, mumps and rubella

Measles

Measles is one of the most highly infectious diseases known. It is transmitted through the respiratory route. The earliest signs of measles infection include high fever, runny nose, cough, red and watery eyes and Koplik spots (small red spots with bluish-white centres) inside the mouth. After several days, a rash appears, usually on the face and upper neck. The rash spreads, eventually reaching the hands and feet and lasts 5 to 6 days before fading. Measles can be severe, particularly in immunosuppressed individuals and young infants. It is also more severe in pregnancy, and increases the risk of miscarriage, stillbirth, or preterm delivery.

Mumps

Mumps is a highly infectious viral infection that can be spread by droplets from the nose and throat, and by saliva. The first symptoms of mumps are usually a raised temperature, swelling and tenderness of salivary glands (parotid) accompanied by headaches, joint pain and general malaise. The swelling can be one sided or affect both sides. Mumps is usually fairly mild in young children, but can cause swelling of the testicles and rarely, infertility in males over the age of puberty.

Rubella

Rubella is a highly infectious viral infection that generally causes a mild, febrile rash-illness. It is spread by respiratory droplets through coughing or sneezing, or by direct contact with the saliva of an infected individual. The symptoms of rubella are mild. Usually, the rash is the first indication of rubella infection. The main symptoms include swollen lymph glands around the ears and back of head 5 to 10 days before the onset of a rash, sore throat and runny nose, mild fever, headache, tiredness, conjunctivitis (sore, itchy, watery, red and/or sticky eyes), painful and swollen joints and a red rash mostly seen behind the ears and on the face and neck. Recovery from rubella is usually rapid and complications rarely occur. Rubella does, however, have serious consequences for pregnant women who are not immune and for the unborn baby if acquired during the first 20 weeks of pregnancy.

MMR vaccine

The combined Measles, Mumps and Rubella vaccine (MMR) was introduced into the UK immunisation schedule in 1988. For more information about measles, mumps and rubella, please refer to the individual disease chapters in the Green Book.

Aim of the MMRV vaccination programme

The aim of the MMRV vaccination programme is to protect children by reducing the incidence and severity of, measles, mumps, rubella and varicella infections.

As has been shown in other countries which include varicella in their routine vaccination schedule, the 2-dose schedule for younger children is predicted to rapidly and dramatically decrease the number of cases of varicella seen. The programme will prevent severe cases of varicella, and other serious complications from the infection which, while rare, may result in hospitalisation or other serious outcomes.

Experience in other countries

Varicella vaccination is included in the routine vaccine schedules of several countries, either as a 2-dose or single-dose strategy, including the USA, Canada, Australia and Germany. Countries that have introduced programmes have observed a significant impact on cases of varicella and resulting hospitalisations. In countries introducing a 2-dose schedule, younger cohorts not eligible for vaccination have also seen reduced incidence because of reduced community transmission. There is also no evidence of increased rates of infection among those who are not eligible for vaccination due to their age following introduction of a programme.

Timelines and eligibility  

Varicella vaccination will be introduced into the routine childhood immunisation schedule from 1 January 2026. The combined measles, mumps, rubella and varicella (MMRV) vaccine will be used, meaning that children due their first or second MMR vaccine from 1 January 2026 should now be offered combined MMRV vaccine instead of MMR.

MMRV will be offered both routinely and as a selective single dose ‘catch-up’ programme for older children without a history of chickenpox infection. See table 1 below for details:

Table 1. MMRV vaccination eligibility by date of birth

Date of birth	Age on 31 December 2025	New programme from 1 January 2026	Child’s full schedule for MMR/MMRV
01/01/2025 or later	Under 1 year	2 doses of MMRV at 12 and 18 months	12 months: MMRV 18 months: MMRV
01/01/2024 to 31/12/2024	1 year to under 18 months	2 doses of MMRV at 18 months and 3 years 4 months	12 months: MMR [note 1] 18 months: MMRV 3 years 4 months: MMRV
01/09/2022 to 30/06/2024	18 months to under 3 years 4 months	1 dose of MMRV at 3 years 4 months	12 months: MMR 3 years 4 months: MMRV
01/01/2020 to 31/08/2022	3 years 4 months to under 6 years	Selective catch-up from 1 Nov 2026 to 31 Mar 2028 for those who have not yet had chickenpox infection or 2 doses of varicella vaccination[note 2]	12 months: MMR dose 1 3 years 4 months: MMR dose 2 MMRV catch up offer
31/12/2019 or before	6 years old and older	Not eligible	12 months: MMR dose 1 3 years 4 months: MMR dose 2

Note 1: if a child has not yet received a dose of MMR vaccine that they should have received, for example if they turned 12 months of age in mid to late December 2025, MMRV should be given and the dose of MMRV at 3 years 4 months is not required.

Note 2: there is no requirement for practices to check the history for those who respond to the offer.

The recommended vaccines 

There are currently 2 MMRV vaccines available for the routine immunisation programme: ProQuad® (MSD) and Priorix-Tetra® (GSK). Both vaccines have been licensed for a number of years and are used in several other countries including Canada, Germany and Australia. The vaccines are considered clinically equivalent and interchangeable. Where 2 doses are to be given, they do not have to be the same brand. ProQuad® contains porcine gelatine (see gelatine section below).

How the vaccines work

ProQuad® and Priorix-Tetra® are both live attenuated vaccines which means they contain weakened forms of the viruses that cause measles, mumps, rubella, and varicella. As the vaccine virus is weakened it does not cause the disease itself, but it does cause the immune system to respond in the same way it does to natural infection thereby promoting a full, long-lasting antibody response.

Vaccine effectiveness 

The MMR vaccine is highly effective at preventing measles, mumps and rubella - one dose is 95% effective in preventing measles and this increases further with 2 doses (3). Varicella vaccine effectiveness is also very high, with effectiveness estimated to be 93% after one dose and 97% after 2 (4). Combination vaccines such as MMRV are carefully studied to ensure that the safety and effectiveness of all the components is not affected by combining them.

Studies have also shown that protection from these vaccines is long-lasting: a review of studies found that vaccine effectiveness against varicella (any severity) after 2 doses of MMRV or MMR + V in children aged 11 to 22 months was 95% in a 10 year follow-up (3) and 25 years of surveillance in the USA has shown no decrease in vaccine effectiveness over time when using a 2-dose schedule (5).

Although breakthrough infection (infection despite vaccination) can occur, varicella disease tends to be much milder in children who have been vaccinated compared to those who have not, with fewer lesions and less fever. The vaccine is also extremely effective in protecting against severe varicella disease, even if only one dose is administered.

Since the varicella vaccination programme was introduced in the USA, it is estimated that, in 25 years, more than 91 million varicella cases, 238,000 hospitalisations, and almost 2,000 deaths have been averted (6).

Prescription only medicines

All vaccines are classified as prescription only medicines (POMs). This means that they are subject to legal restrictions and there needs to be an appropriate legal framework in place before they can be supplied and or administered. Any person who supplies and administers a vaccine must have a legal authority to do so. This legal authority may be in the form of a written patient specific prescription, a Patient Specific Direction (PSD) or a Patient Group Direction (PGD).

The UK Health Security Agency (UKHSA) has developed and published an MMRV PGD. This will be available to download from the Immunisation PGD templates collection webpage. The UKHSA immunisation PGD templates require further authorisation in Section 2 of the PGD document before they can be used. The PGD is not legal or valid without signed authorisation.

Vaccine ordering

Vaccines for the national vaccination programmes in England should be ordered via the ImmForm website. Healthcare practitioners should refer to this website and Vaccine Update  (the vaccination newsletter for healthcare practitioners) for current information on vaccine availability. To minimise wastage due to fridge failures or expiry, healthcare practitioners are reminded to order no more than 2 weeks’ worth of stock, rather than over-ordering or stockpiling vaccines. Vaccines should be ordered, stored and monitored as described in the Green Book Storage, distribution and disposal of vaccines chapter.

Practices should continue to order MMR vaccine as well as MMRV vaccine as this will be required for older children (born before 1 January 2020) and adults who require catch up vaccination.

Where a clinician has decided that it is clinically appropriate to vaccinate an individual who is not eligible for the national MMRV vaccination programme, GP practices would need to purchase the MMRV vaccine directly from the manufacturer and then reclaim the cost of the vaccine through their usual process.

Vaccine storage

Both ProQuad® and Priorix-Tetra® should be stored in a vaccine refrigerator between 2°C and 8°C. The vaccines should be stored in the original packaging to protect them from light, to ensure that the component parts are kept together and to retain the batch number and expiry date for the entire product which is printed on the outer vaccine carton. The vaccines should not be frozen.

Further information on vaccine storage is available in the manufacturer’s Summary of Product Characteristics (SmPC):

• Priorix-Tetra® Powder and solvent for solution for injection in pre-filled syringe - SmPC

• ProQuad® powder and solvent for suspension for injection in a pre-filled syringe SmPC)

Effectiveness cannot be guaranteed for vaccines unless they have been stored at the correct temperature and in the correct conditions. Those responsible for the ordering, storage and use of vaccines should be familiar with the recommendations in the Green Book Storage, distribution and disposal of vaccines chapter. Vaccines should not be over-ordered or stockpiled.

Vaccine composition

The MMRV vaccine ProQuad® contains:  

• Sucrose
• Hydrolysed gelatin
• Sodium chloride
• Sorbitol (E 420)
• Monosodium glutamate
• Sodium phosphate
• Sodium bicarbonate
• Potassium phosphate
• Potassium chloride
• Medium 199 with Hanks’ Salts
• Minimum Essential Medium, Eagle (MEM)
• Neomycin
• Phenol red
• Hydrochloric acid (to adjust pH)
• Sodium hydroxide (to adjust pH)
• Urea

ProQuad® contains porcine gelatine.

The MMRV vaccine Priorix-Tetra® contains:

• Amino acids (containing phenylalanine)
• Lactose anhydrous
• Mannitol (E 421)
• Sorbitol (E 420)
• Medium 199 (containing phenylalanine, para-aminobenzoic acid, sodium and potassium)
• This vaccine contains a trace amount of neomycin

Priorix-Tetra® does not contain porcine gelatine. 

The solvent for both vaccines is water for injection. Both vaccines contain trace amounts of neomycin.

Gelatine     

ProQuad® contains porcine gelatine. Priorix-Tetra® should be offered to children whose parents or carers do not wish them to receive a vaccine containing porcine gelatine.

The following resources may also be helpful:

• UKHSA guidance on the use of human and animal products in vaccines
• UKHSA guidance on vaccines and porcine gelatine
• vaccine ingredients from The Vaccine Knowledge Project

Phenylalanine

ProQuad® and Priorix-Tetra® vaccines contain a source of phenylalanine. The National Society for Phenylketonuria (NSPKU) advise the amount of phenylalanine contained in vaccines is negligible and therefore strongly advise individuals with PKU to take up the offer of vaccination.

Vaccine presentation and preparation

Both ProQuad® and Priorix-Tetra® require reconstitution prior to use.

ProQuad® is supplied as powder in a vial with the solvent for reconstitution in a pre-filled syringe. Before mixing with the solvent, the powder is a white to pale yellow compact crystalline cake. The solvent is a clear colourless liquid. The reconstituted (dissolved) vaccine should be inspected visually. When completely reconstituted, the vaccine is a clear pale yellow to light pink liquid. ProQuad® will be supplied in single dose packs with 2 needles per pack.

Priorix-Tetra® is supplied as powder in a vial with 0.5 ml of solvent in a pre-filled syringe with plunger stopper (butyl rubber). Priorix-Tetra® is supplied as a whitish to slightly pink coloured powder cake, a portion of which may be yellowish, and a clear colourless solvent (water for injections) for reconstituting the vaccine. The vaccine must be reconstituted with the solvent provided. The reconstituted (dissolved) vaccine should be inspected visually. Its colour may vary from clear peach to fuchsia pink due to minor variations of its pH. It may contain translucent product-related particulates. This is normal and does not impair the performance of the vaccine. Priorix-Tetra® will be supplied in 10 dose packs.

If either of the vaccines presents with other colouration or contains other particulate than as described in the SmPC, the vaccine must not be administered.

Clear instructions on how to prepare both ProQuad® and Priorix-Tetra® vaccine for administration can be found in the SmPC. Immunisers are strongly encouraged to look at the SmPC before preparing the vaccine for the first time.

Vaccine administration

ProQuad® and Priorix-Tetra® should be reconstituted according to the manufacturer’s instructions. Once reconstituted, the vaccine should be administered immediately. For both vaccines, one reconstituted dose is 0.5ml.

Both ProQuad® and Priorix-Tetra® can be administered via the intramuscular route (IM) or subcutaneously (SC). However, as part of the national immunisation programme, it is recommended they are administered IM.

The preferred sites for IM vaccinations are the anterolateral aspect of the thigh or the deltoid area of the upper arm. Whilst the anterolateral aspect of the thigh is the preferred site for infants under one year old, the deltoid area of the upper arm is suitable for individuals over one year of age. However, if it is not possible to give the vaccine into the deltoid area of the anterolateral aspect of the thigh can be used. As children get older, the deltoid area of the upper arm is likely to be easier to access, but there is no clinical preference for one of these sites over the other for any of the vaccines used in the routine childhood programme.

Vaccine dosage and schedule

ProQuad® and Priorix-Tetra® should be administered after reconstitution using the full volume of the reconstituted vaccine, drawn up into the syringe.

The nationally recommended vaccination schedule for MMRV (ProQuad® or Priorix-Tetra®) is a 2 dose schedule for younger children and a single dose for older children who are receiving the catch-up programme. Please refer to the table above in the ‘timelines and eligibility’ section for more information. Where 2 doses are indicated, these should be given a minimum of 4 weeks apart.

For those who are behind schedule with their vaccinations, healthcare professionals should use the ‘vaccination of individuals with uncertain or incomplete immunisation’ algorithm to identify any outstanding vaccinations.

Vaccination for individuals with bleeding disorders

Individuals with bleeding disorders may be vaccinated intramuscularly if, in the opinion of a doctor familiar with the individual’s bleeding risk, vaccines or similar small volume intramuscular injections can be administered with reasonable safety by this route. If the individual receives medication or treatment to reduce bleeding, for example treatment for haemophilia, intramuscular vaccination can be scheduled shortly after such medication or treatment is administered.

Individuals on stable anticoagulation therapy, including individuals on warfarin who are up to date with their scheduled INR testing and whose latest INR was below the upper threshold of their therapeutic range, can receive intramuscular vaccination. A fine needle (equal to 23 gauge or finer calibre such as 25 gauge) should be used for the vaccination, followed by firm pressure applied to the site (without rubbing) for at least 2 minutes.

If in any doubt, consult with the clinician responsible for prescribing or monitoring the individual’s anticoagulant therapy. 

Both MMRV vaccines are licensed to be given subcutaneously, therefore a healthcare professional may determine this is a preferred route of administration for an individual with a bleeding disorder.

The individual or their carer should be informed about the risk of haematoma from the injection.

Contraindications and precautions

There are very few individuals who cannot receive MMRV vaccine. When there is doubt, appropriate advice should be sought from a consultant paediatrician, the local screening and immunisation team, or consultant in public health, rather than withholding the vaccine.

The vaccine should not be given to:

• those who are immunosuppressed (see the Green Book Contraindications and special considerations chapter for more detail)
• those who have had a confirmed anaphylactic reaction to a previous dose of a measles-, mumps-, rubella- or varicella-containing vaccine
• those who have had a confirmed anaphylactic reaction to neomycin or any other component of the vaccine
• pregnant women

Immunisation of individuals who are acutely unwell with a fever should be postponed until they have recovered fully. This is to avoid confusing the diagnosis of any acute illness by wrongly attributing any sign or symptoms to the adverse effects of the vaccine. The presence of a minor illness, such as the common cold, is not a contraindication to immunisation.

MMRV is not recommended in infants younger than 9 months old.

For full details refer to the Green Book Varicella chapter.

Egg allergy

Measles and mumps vaccine viruses are grown through a process which uses chick embryo cells; this is different to chicken egg. Rubella and varicella vaccine viruses are not grown using chick embryo cells. The MMRV vaccines do not use egg or contain egg-derived products in the end formulation.

All children with an egg allergy should receive the MMRV vaccination as a routine procedure in primary care. Evidence suggests that anaphylactic reactions to MMR vaccine are not associated with hypersensitivity to egg antigens but to other components of the vaccine (such as gelatine) (7). In 3 large studies with a combined total of over 1,000 patients with an egg allergy, no severe cardiorespiratory reactions were reported after MMR vaccination (8), (9), (10),(11).

Children who have had documented anaphylaxis to the vaccine itself should be assessed by an allergist (12).

Salicylates

Increased risk of Reye’s syndrome has been reported in children treated with aspirin during natural varicella infection. Aspirin and systemic salicylates are therefore not recommended in children aged under 16 except under medical supervision. However, experience in other countries has found no reports of Reye’s syndrome following varicella vaccination. There is no need to avoid salicylates before or after receiving varicella vaccines, if their use is clinically indicated. The benefit is likely to outweigh the potential risk of Reye’s syndrome (13).

Immunosuppression and HIV infection

MMRV vaccines are contraindicated in children who are severely immunosuppressed. For immunosuppressed children who require protection against varicella, seek advice from a specialist.

MMRV vaccines can be given to children living with HIV with no or moderate immunosuppression (CD4 count >500 for children aged 1 to 5 years). This should be discussed with their specialist.

Children with an immunosuppressed household or close contact

Vaccination with a varicella-containing vaccine is recommended for healthy susceptible contacts of immunosuppressed patients where continuing contact is unavoidable (for example, siblings of a leukaemic child, or a child whose parents or sibling is undergoing chemotherapy). Children eligible for MMRV should be vaccinated as per the schedule. There is no risk of transmission of the vaccine viruses to the immunosuppressed contact unless the vaccinated child develops a post-vaccination rash (see section on post-vaccination rash).

Adverse reactions commonly associated with the administration of MMRV

For both MMRV vaccines (ProQuad® and Priorix-Tetra®) the most common adverse reactions (affecting between 1 in 10 and 1 in 100 of the trial participants) include tenderness, redness, or swelling at the injection site, fever, irritability, and rash (including a measles- or varicella-like rash).

Rash following vaccination    

Children may develop a rash following vaccination with MMRV vaccine which may be related to either the measles or varicella component of the vaccine.

Measles-like rash

Rash due to the measles component of the vaccine is most likely to occur about a week after immunisation, and last about 2 to 3 days. It is a measles-like, maculopapular rash. Transmission of measles virus from vaccinees to susceptible contacts has never been documented. Transmission of rubella and mumps vaccine viruses has also not been documented.

Varicella-like rash

Rash due to the varicella component of the vaccine usually occurs within one month of immunisation. It is typically a vesicular rash, though may be papular.

Rash at the injection site is relatively common. It should not prevent children from attending childcare or educational settings, but it should be covered with clothing as a precaution.

Disseminated rash, or localised rash other than at the injection site, is rare. Given the current epidemiology, it is more likely to be due to naturally acquired chickenpox infection. Children with this sort of rash should be seen by their GP to determine whether it is due to the vaccine virus or to coincidental wild-type chickenpox.

Transmission of vaccine virus from immunocompetent vaccinees with a post-vaccination rash to susceptible close contacts has occasionally been documented, but the risk is very low. If a localised rash develops then the lesions should be covered (with clothing) to further reduce the risk of transmission. If the rash is disseminated, then the risk of transmission is higher. Immunosuppressed contacts should be offered post-exposure prophylaxis (see guidance). Immunocompetent pregnant contacts can be reassured that the risk of infection is very low . Whilst the vaccine SmPC suggest transmission of varicella is theoretically possible where a rash does not develop, transmission in the absence of a post-vaccination rash has not been documented (14).

Febrile Convulsions (seizures)

Fever following vaccination with MMRV vaccine is well documented and usually occurs during the first 2 weeks post vaccination.

Febrile convulsions can occur when a child develops a high temperature of any cause. They are most common between 6 months to 6 years of age; 2 to 5% of children will experience febrile convulsions before the age of 5. Febrile convulsions are self-limiting, with no long-term consequences.  

There is a small risk of febrile convulsions following vaccination with the first dose of MMRV. These usually occur 5 to 10 days following vaccination. One study estimated the absolute risk to be approximately 1 in 1,000 doses in the 7 to 10 days following vaccination (15). The risk of a febrile convulsion following natural measles infection is far higher than the risk following vaccination: 1 in 43 cases of measles (16). An increased risk of febrile convulsions following the second dose of MMRV has not been observed.

The risk of having a febrile convulsion following the first dose of MMRV vaccine is higher than when giving separate MMR and monovalent varicella vaccines at the same time (15). This risk was carefully considered by the JCVI when making their vaccine recommendation. It was felt that the benefits of offering a combination vaccine in improved uptake, parental acceptance and fewer injections for the child, outweighed the low risk of febrile convulsions.

Despite the low risk of children experiencing a febrile convulsion following vaccination with MMRV vaccine, it is important that parents are aware and informed of the possible risk. If a parent suspects that their child has had a febrile convulsion or another serious reaction following administration of any vaccine, including MMRV vaccine, they should be advised to seek medical attention and it should be reported via the Yellow Card Scheme.

As fever following vaccination with MMRV vaccine may occur at any point within 2 weeks of vaccination, there is no need for the child to be offered prophylactic paracetamol prior to administration of the MMRV vaccine. Children can, however, receive paracetamol if they develop any post vaccine related symptoms.

A previous personal or family history of febrile convulsions is not a contraindication to vaccination with MMRV.

Idiopathic thrombocytopenic purpura

Idiopathic thrombocytopenic purpura (ITP) occurs rarely following MMRV vaccination, usually within six weeks of the first dose. The risk of developing ITP after MMRV vaccine is much less than the risk of developing it after infection with wild measles or rubella virus.

If ITP has occurred within 6 weeks of the first dose of MMRV, then blood should be taken and tested for measles antibodies  before a second dose is given. Serum should be sent to the UKHSA Virus Reference Laboratory (Colindale), which offers free, specialised serological testing for such children. If the results suggest a lack of protection against measles, then a second dose of MMRV is recommended. Serological testing for the mumps, rubella, and varicella components is not recommended.

There is no evidence of an association between the second dose of MMR and ITP, and this is expected to be the same for MMRV. Children with previously diagnosed ITP do not have an increased risk of ITP following MMRV; this is not a contraindication to vaccination.

Encephalitis  

Encephalitis is a known complication of wild-type varicella and measles infections, associated with approximately 2 to 3 in 100,000 cases and 100 in 100,000 cases respectively (17),(18).

Post-marketing surveillance of varicella-containing vaccines has found a small number of cases of encephalitis which occurred after vaccination, but an association has not been quantified.   

Surveillance of adverse events following varicella vaccination in the USA recorded 80 cases of encephalitis following monovalent varicella vaccine, and 22 cases following MMRV, representing a rate of 0.06 cases per 100,000 doses given for both vaccines. Varicella zoster virus was detected in 3 of these cases, of which 1 was confirmed as vaccine virus. Many of these cases occurred in immunocompromised children, for whom varicella-containing vaccines are contraindicated (19). The UK has a screening programme for severe combined immunodeficiency, which reduces the risk that a child will have undiagnosed immunocompromise when being offered vaccination.

The risk of encephalitis associated with varicella and measles infections is far greater than the risk following vaccination.

Reporting adverse reactions

All suspected reactions following MMRV should be reported to the Medicines and Healthcare product Regulatory Agency using the Yellow Card scheme:

• online at Yellow Card Scheme
• downloading and using the Yellow Card app for Apple devices or Android devices
• by calling the Yellow Card scheme on 0800 731 6789 (9am to 5pm)

Common issues and questions about MMRV vaccination

What should be given to children who are travelling to an endemic area or are identified in a local outbreak?

Children aged 6 months to one year of age who are travelling to a country with a high incidence of measles or who are identified as part of a local outbreak and who require measles-containing vaccine should be given MMR rather than MMRV. However, any dose of MMR (or MMRV if given in error) administered below the age of one year should be discounted as residual maternal antibodies may reduce the response to the vaccine.

Why are some children being offered two MMRVs when they have already received one MMR?

Children born between 1 July 2024 and 31 December 2024 should have received an MMR at 12 to 13 months, prior to the introduction of the MMRV programme. They will be offered 2 MMRV vaccines at 18 months and 3 years 4 months. The rationale for this is twofold. Children in this age cohort are less likely than older children to have been exposed to chickenpox already and will have more peers who are susceptible to chickenpox. They also have 2 further scheduled appointments which present the opportunity to give them 2 MMRV doses. There are no safety concerns with giving 3 MMR-containing vaccines.

As both MMR and MMRV vaccines are live, there is no additional risk of adverse events from giving additional doses. The frequency of adverse events following a live vaccine (with the exception of BCG vaccine) usually decreases with the number of doses given, as any antibodies made in response to the first dose will neutralise the vaccine virus in subsequently administered doses of live vaccines.

What should be offered to children who are behind schedule with their MMR or MMRV vaccinations?

Children born on or after 1 January 2020 and who require MMR catch-up should be offered this using MMRV. This is the cohort of children who are eligible for at least one dose of MMRV through either the routine schedule or the selective catch-up campaign.

Where a child is behind schedule with their MMR or MMRV vaccination, there are a few factors which must be considered when planning their catch-up vaccinations. Due to childhood schedule changes which were implemented 1 July 2025, the timing as to when children receive their second dose of an MMR-containing vaccine is different depending on their date of birth (some children are due this at 18 months and some at 3 years 4 months). There may be circumstances where a child who is behind schedule may receive an additional or earlier dose than if they were following the schedule, for example:

• a child may be eligible for one MMRV vaccine according to the routine or selective catch-up programme but receives 2 MMRV vaccines because this is the only MMR-containing vaccine being offered from 1 January 2026 to children born from 1 Januaryn 2020
• a child may be eligible for one MMRV from November 2026 as part of the catch-up campaign but receives this earlier to catch them up for MMR-containing vaccines

Both these scenarios are acceptable, in the best interest of the child, and should only be required in a small number of circumstances.

The below table (Table 2) has been created to aid vaccinators in determining which vaccine a child who is behind with their schedule may require and when. For children who present for vaccination at the correct scheduled time, the table in the eligibility section above should be followed.

To use the table, first consider the age of the child presenting for vaccination, then their MMR-containing vaccination status, and then follow the advice within the age category for their date of birth. Where a previous dose of MMR has been given, a minimum 4-week interval should be left before any subsequent doses.

Table 2. What to offer a child who is behind with their schedule

Table 2a. Children aged 1 year to 18 months

No previous doses of MMR	One previous dose of MMR vaccine and no previous doses of MMRV
Action: Offer first dose of MMRV Then: Offer second dose of MMRV at 18 months and at least 4 weeks after the first dose of MMRV If they have received both doses of MMRV in this way before 3 years 4 months, they will not require any further doses of MMRV with their pre-school booster DTaP/IPV vaccine.	Date of birth: 01/07/2024 to 31/12/2024  If born in the UK, these children should have received the first dose of MMR at 12 months Action: Offer first dose of MMRV at 18 months and at least 4 weeks after the first dose of MMR Then: Offer second dose of MMRV at 3 year 4 months.
	Date of birth: 01/01/2025 onwards These children should not have received MMR unless vaccinated abroad or as part of an outbreak response. They should have been offered the first dose of MMRV at 12 months. Action: Offer first dose of MMRV at least 4 weeks after MMR vaccine was given (second MMR-containing vaccine) Then: Offer second dose of MMRV at 18 months and at least 4 weeks after the first dose of MMRV

Table 2b. Children aged 18 months to under 3 years 4 months

No previous doses of MMR	One previous dose of MMR vaccine and no previous doses of MMRV
Date of birth: 01/09/2022 to 30/06/2024  Action: Offer first dose of MMRV  Then: Offer second dose of MMRV at 3 years 4 months and at least 4 weeks after the first dose of MMRV  This advice for the timing of the second dose keeps the child in line with what other children in their DOB cohort will receive. This is why it differs from the advice for timing of second MMRV given for other DOBs	Date of birth: 01/09/2022 to 30/06/2024 These children should have received an MMR vaccine at 12 months of age and are then due to receive 1 dose of MMRV at 3 years 4 months of age months of age. Action: Offer a dose of MMRV (second MMR-containing vaccine) at 3 years 4 months
Date of birth: 01/07/2024 onwards Action: Offer first dose of MMRV Then: Offer second dose of MMRV 4 weeks later (to give them a 2nd dose of MMR-containing vaccine which their age cohort will have already received) If they have received both doses of MMRV in this way before 3 years 4 months of age, they will not require any further doses of MMRV with their pre-school booster DTaP/IPV vaccine.	Date of birth: 01/07/2024 to 31/12/2024 These children should have received an MMR vaccine at 12-months of age and MMRV at 18 months of age. Action: Offer first dose of MMRV (second MMR-containing vaccine) Then: Offer second dose of MMRV at 3 years 4 months and at least 4 weeks after the first dose of MMRV
	Date of birth: 01/01/2025 onwards These children should not have received MMR unless vaccinated abroad or as part of an outbreak response. They should have been offered 2 MMRVs at 12 and 18 months. Action: Offer first dose of MMRV (second MMR-containing dose) Then: Offer second dose of MMRV 4 weeks later

Table 2c. Children aged 3 years 4 months to under 6 years

No previous doses of MMR	One previous dose of MMR vaccine and no previous doses of MMRV
Action: Offer first dose of MMRV Then: Offer second dose of MMRV 4 weeks later  If they receive 2 MMRV doses in this way, there is no requirement to recall this child for the selective catch-up between November 2026 and March 2028.	Date of birth: 01/01/2020 to 31/08/2022 These children should have received 2 MMR vaccines at 12 months and 3 years 4 months and are being offered MMRV in the selective catch up programme. Action: Offer MMRV as their second dose of an MMR-containing vaccine. This should be offered when they present. As this cohort are eligible for the selective catch-up programme, these children can still be offered a further dose of MMRV in the selective catch-up between November 2026 and March 2028.
	Date of birth: 01/09/2022 to 30/06/2024 These children should have received 1 MMR at 12 months and 1 MMRV at 3 years and 4 months Action: Offer a dose of MMRV as their second dose of an MMR-containing vaccine

Table 2d. Children aged 6 years and older

No previous doses of MMR	One previous dose of MMR vaccine and no previous doses of MMRV
Date of birth: 31/12/2019 or before Action: Offer first dose of MMR Then: Offer second dose of MMR 4 weeks later	Date of birth: 31/12/2019 or before Action: Offer second dose of MMR
Date of birth: 01/01/2020 onwards Action: Offer first dose of MMRV Then: Offer second dose of MMRV 4 weeks later	Date of birth: 01/01/2020 to 30/06/2024 These children will have been eligible for one dose of MMRV Action: Offer a dose of MMRV (second MMR-containing dose)

What should be given to children who have previously received 2 doses of MMR and are scheduled to receive MMRV?

Children aged under 3 years 4 months who have received 2 MMR vaccines prior to their scheduled appointments for MMRV, for example for travel or outbreak reasons, should still be offered MMRV as per the schedule for their date of birth.

What should be given to children who have moved to the UK having been vaccinated abroad?

If an individual has received any previous doses of MMR or MMRV vaccine, healthcare professionals must check when they were administered to ensure that they align with the UK national immunisation schedule and that they have received the correct antigens for their age. For example, a child moving from overseas may have received 2 valid doses of MMR vaccine but they may also be eligible for further doses of MMRV vaccine. These should be offered as per the schedule for their date of birth. If they have only received one dose of MMR vaccine, the table above can be used to determine what they require.

Healthcare professionals should use the ‘vaccination of individuals with uncertain or incomplete immunisation’ algorithm to identify any other outstanding vaccinations.

What counts as a valid second dose of MMR-containing vaccine?

The first dose of MMRV should be administered from 12 months of age.

The second dose of MMRV vaccine is now routinely given at 18 months of age, but if needed can be given at any time from three months after the first dose. Allowing 3 months between doses is likely to maximise the response rate, particularly in young children under the age of 18 months where maternal antibodies may still be present and interfere with the response to vaccination. Where protection against measles is urgently required, the second dose can be given one month after the first. If the child is given the second dose less than three months after the first dose and at less than 18 months of age, then the routine 18-month dose (which would constitute a third dose in this case) should be given in order to ensure full protection.

What should school immunisation services do if they cannot record MMRV in their IT systems?

Children born on or after 1 January 2020 who need to be caught up with MMR should be given MMRV if possible. However, SAIS and 0 to 19 service provider IT systems may not be ready to do this from 1 January 2026. If providers do not have a mechanism for correctly documenting MMRV in relevant GP and CHIS data systems they should follow the guidance below until the systems are remedied:

• children born between 1 January 2020 and 31 August 2022 who present late for either their first or second MMR dose should receive an MMR. These children will be invited for an MMRV as part of the selective catch-up programme from November 2026
• children born on or after 1 September 2022 who have never had an MMR-containing vaccine should be given their first dose of MMR. This is very important to ensure that children receive a measles-containing vaccine at the earliest opportunity. These children remain eligible for MMRV and their parents or carers should be strongly advised to attend their GP for an MMRV vaccine so that their child can also be protected against chickenpox
• children born on or after 1 September 2022 with a history of one MMR dose but who are late for their second dose should be referred to their GP for an MMRV. However, if the provider thinks the child is not likely to be taken to the GP at a later date, they should give a second MMR then. These children remain eligible for MMRV and their parents should still be encouraged to take them to their GP so they can be offered protection against chickenpox

Where a child who is eligible for an MMRV vaccine attends their GP practice following an MMR vaccine administered by the SAIS team, a minimum interval of 4 weeks should be observed between the doses. These children will receive an additional dose of measles, mumps and rubella antigens, but this is of no clinical concern.

What should be offered to a child who is late attending for their first dose of MMR?

Children born between 1 July 2024 and 31 December 2024 who were eligible to receive MMR at 12 months of age but are late attending for this dose should be offered MMRV when they do attend for their ‘12 month’ vaccinations along with their MenB and PCV13 booster doses. They should then receive a second MMRV vaccine at 18 months of age (or a minimum of 4 weeks after their first MMRV if they are older than this when they present) with their DTaP/IPV/Hib/HepB vaccine. If they have received both doses of MMRV in this way before 3 years 4 months of age, they will not require any further doses of MMRV with their pre-school booster DTaP/IPV vaccine.

Older children’s eligibility for MMRV vaccination

Children born from 1 January 2020 are eligible for a dose of MMRV in the selective catch-up programme which will be delivered between 1 November 2026 and 31 March 2028. This means that some children will be over 6 years of age when they are offered this dose. Their eligibility is defined by their date of birth, not their age.

What vaccine should be given to individuals born before 1 January 2020?

Individuals born before 1 January 2020 who require vaccination against measles, mumps and rubella should be offered the MMR vaccine. However, if MMRV is the only vaccine available at the time they present, MMRV can be given if it is felt that the individual would not return if asked to wait until MMR vaccine was available or if immediate protection is required. 

What should be given to a child who has previously had measles, mumps, rubella or varicella infection?

Previous infection with varicella, measles, rubella or mumps is not a contraindication to MMRV vaccine. When an individual who has previously been infected with any of these diseases receives MMRV vaccine, their pre-existing immunity will inhibit replication of the vaccine viruses.

In the routine MMRV programme, a child who has had chickenpox infection previously should still be offered the MMRV vaccine to protect them against measles, mumps and rubella.

In the selective catch-up MMRV programme, a child who has received 2 doses of MMR and has had chickenpox infection does not require MMRV. However, there is no requirement for healthcare professionals to check for pre-existing immunity to chickenpox prior to giving MMRV vaccine.

From 1 January 2026, MMR vaccine will no longer be available for the NHS routine childhood programme and will only be available for individuals outside of the routine childhood programme (for example, catching up older individuals born before 1 January 2020 who have not received 2 doses of MMR and are not eligible for varicella vaccination).

What to do if parents or carers are unsure if their child has previously had varicella infection

If a parent or a carer is unsure whether their child has previously had varicella infection, they should still be vaccinated with MMRV according to the national schedule.

Previous infection with varicella, measles, rubella or mumps is not a contraindication to either MMR or MMRV vaccine. Should an individual who has previously been infected with any of these diseases receive MMR or MMRV vaccine, their pre-existing immunity will inhibit replication of the vaccine viruses. The vaccine will also boost antibodies made following previous infection.

Is MMRV as effective as MMR?

Parents or carers can be reassured that their child can expect the same level of protection against measles, mumps and rubella regardless of which vaccine is administered (MMR or MMRV). The MMRV vaccine will also protect their child against varicella. Many countries, including the USA, offer a mixed schedule of MMR and MMRV to their children.

Will one dose of MMRV offer sufficient protection against varicella?

Parents or carers who are concerned their child will only receive one dose of a varicella containing vaccine (those born between 1 January 2020 and 30 June 2024), can be reassured that a high level of vaccine effectiveness can usually be expected after one dose. Furthermore, where children who have received only one dose of a varicella-containing vaccine go on to develop varicella infection from community exposure, the disease is usually milder than if no vaccine had been received. One dose is extremely effective at protecting against severe varicella disease. In addition, it is likely that children in the age cohort who are only eligible for one dose will have already been exposed to varicella infection.

Regardless of age, all children should receive 2 doses of MMR-containing vaccine.

Administering MMRV to children who have had previous varicella vaccination

Children who have been privately vaccinated with one dose of varicella vaccine, or who received a dose because of contact with an immunosuppressed individual or in an outbreak situation, should be offered the catch-up dose of MMRV as they will benefit from receiving this.  

Children who have already received 2 doses of varicella vaccine for any of the above reasons will not benefit from an additional MMRV vaccine. However, there is no requirement for GP practices to check prior varicella vaccination history and children can still receive the single dose catch-up MMRV if requested by their parents or carers.

Children who are due to have MMRV according to the routine schedule, but have had previous varicella vaccination, should still be given MMRV according to the schedule. This ensures they are protected against measles, mumps, and rubella, and that they have received the varicella component at an appropriate age.

Can parents or carers request MMR instead of MMRV?

Healthcare professionals should find out why the parents or carers are requesting MMR vaccine rather than MMRV vaccine. If they are concerned that the child has already had varicella infection or previous varicella vaccination, they can be reassured the child can still safely receive MMRV vaccine.

Parents or carers can be reassured that their child can expect the same level of protection against measles, mumps and rubella from the MMRV vaccine as from the MMR vaccine.

Previous infection with varicella, measles, rubella or mumps is not a contraindication to either MMR or MMRV vaccine. Should an individual who has been previously infected with any of these diseases receive MMR or MMRV vaccine, their pre-existing immunity will inhibit replication of the vaccine viruses.

Previous vaccination with a varicella containing vaccine is also not a contraindication to a child receiving MMRV vaccine. As MMR and MMRV vaccines are live, there is no additional risk of adverse events from giving additional doses. The frequency of adverse events following a live vaccine (with the exception of BCG vaccine) usually falls with the number of doses given, as any pre-existing antibodies will neutralise subsequently administered doses of live vaccines.

Children should receive the vaccine they are eligible for according to the national schedule, and healthcare professionals should not offer parents or carers the option for alternative vaccines.  From 1 January 2026, MMRV replaces MMR in the routine schedule. MMR will only be available outside the routine schedule, for example, for catching up an older child with incomplete vaccination history.

A study conducted by Sherman et al in 2022, (20) researching parental acceptance of and preferences for administration of routine varicella vaccination in the UK, found most parents were accepting of a varicella vaccine being introduced to the childhood programme. Furthermore, most parents preferred a combined MMRV vaccine, rather than an additional injection.

Parents or carers declining MMRV but requesting varicella vaccination

A monovalent varicella vaccine will not be offered or available for the NHS routine or selective catch-up programmes. The importance of vaccinating against measles, mumps and rubella should be discussed with parents and carers and healthcare professionals should find out why they are declining MMRV vaccine.

Parents or carers requesting their child’s second dose of MMRV is brought forward

Children should receive their second dose of MMRV according to the national schedule unless there is a particular clinical reason to bring this forward, for example, if travelling to a measles endemic country or if the child is a contact of a case of measles.  

Parents or carers requesting vaccination of children not included in the eligible cohorts

The MMRV vaccine should only be administered to those children who are eligible as part of the national programme. The eligibility criteria for the programme have been decided to ensure there is enough vaccine to protect those at greatest risk and to achieve the maximum benefit for public health. Therefore, older children who do not fall within the eligibility criteria for the routine schedule or the catch-up campaign should be offered MMR vaccine. These children will be over 6 years of age and therefore it is likely they will have already been exposed to varicella infection, so may already be immune.

There is further advice in the Green Book Varicella chapter relating to children and/or adults who may be eligible for varicella vaccine outside of the national schedule (such as those who are non-immune healthy susceptible close household contacts of immunocompromised individuals or non-immune healthcare workers).

Private vaccination

GPs are not permitted to offer any vaccination privately to individuals registered at their practice.

GPs, community pharmacists and all other providers of a private vaccination service must order vaccine directly from the manufacturer. They cannot use stock centrally procured for the national programme.

Parents or carers whose child is not eligible to receive a varicella containing vaccine as part of the national programme but who wish to pay for the vaccine privately should be advised to discuss their request with a private provider and be made aware that they will be liable for the full cost of the vaccine and any additional administration charges that the private provider may apply.

Should children attend childcare, nursery or school following vaccination?

While some children may experience mild side effects after MMRV vaccination, there is no medical reason to exclude a vaccinated child from an educational or childcare setting if they are feeling well. This practice could potentially discourage parents from getting their children vaccinated and increase the risk of having outbreaks in nurseries and schools.

All medicines can cause side effects, but global health authorities agree that immunisation is the safest way to protect children’s health. If a parent or carer feels their child is well enough to attend nursery or school after vaccination, they should be welcomed as normal.

A small number of children may develop a rash following vaccination. These children should be reviewed by a GP (see section on ‘rash following vaccination’).

Administering MMRV at the same time as other vaccines

Where more than one vaccine needs to be given at the same appointment, the vaccines should be given at a separate site, preferably in a different limb. If more than one vaccine is given in the same limb, they should be given at least 2.5cm apart. The sites at which each vaccine is given should be noted in the individual’s health records. When co-administered, any reactions experienced are expected to be the same as those experienced when receiving the vaccines separately.

Administering the MMRV vaccine at the same time as the other childhood vaccinations

The MMRV vaccines can safely be given at the same time as, or at any interval from, any of the vaccinations administered as part of the routine childhood schedule. Any adverse reactions (such as fever) that occur within the first 48 hours post-vaccination, are more likely to be as a result of any inactivated vaccines administered. Any adverse reactions after this time are more likely due to MMRV as reactions are due to viral replication which takes several days.

The recommended interval between MMRV and other live vaccines

MMRV can be given at the same time as or at any interval from other live vaccines, with the exception of yellow fever vaccine. Refer to the UK immunisation schedule chapter of the Green Book for more information about this, and the interval required between tuberculin (Mantoux) skin testing and MMRV.

The recommended interval between MMRV vaccine and the administration of blood products

When MMRV vaccine is given within 3 months of receiving blood products, such as immunoglobulin, the immune response to the vaccine may be reduced. This is because such blood products may contain significant levels of measles, mumps, rubella or varicella-specific antibody, which could then prevent vaccine virus replication. Where possible, MMRV should be deferred until 3 months after receipt of such products. If immediate protection against measles or varicella is required in someone who has recently received a blood product (within the last 3 months), MMRV vaccine should still be given. To confer longer-term protection, MMRV should be repeated 3 months after the blood product was given.

Vaccine administration errors

Healthcare practitioners should report all inadvertent vaccine administration errors via their local governance systems so that appropriate action can be taken, lessons can be learnt, and the risk of future errors minimised.

MMRV administered to a child less than 12 months old

Any dose of MMRV (or MMR) vaccine administered to a child under 12 months of age should be discounted and repeated at the correct age.

Where a MMRV or MMR vaccine is inadvertently administered to a very young child, for example at 8, 12 or 16 weeks of age, the parents can be reassured that this is not harmful as it is likely that residual maternal antibodies will inhibit any replication of the virus.

Administraton of MMRV at an incorrect interval

Where a child is behind schedule and is being caught up with their vaccinations, there should be a minimum interval of 4 weeks between  the first and second dose of MMRV vaccine. Where a second dose of MMRV vaccine is administered at a shorter interval than 4 weeks, the second dose should be discounted and repeated at least 4 weeks from the dose inadvertently given early.

Administration of the incorrect vaccine

Where a child who should have received MMRV has received MMR vaccine in error, they should be offered a dose of MMRV vaccine either in the same appointment, or four weeks after the inadvertent dose of MMR. This is because evidence suggests that MMR can inhibit the response to varicella if given within 4 weeks of each other, but not if given at the same time.

Where a child who should have received MMR has received MMRV vaccine, no further action is required. The child will have received the required measles, mumps and rubella antigens in addition to varicella.

Administration of an expired vaccine

All vaccines have an expiry date that is determined by the manufacturer and is clearly documented on the vaccine packaging. Vaccines that have been stored appropriately within the cold chain environment (and as per national recommendations) can be used up until the last day of the month indicated on the expiration date.

Vaccines that have expired should not be administered to patients. Whilst it is unlikely that a vaccine will cease to become effective on the day of expiration, given its prolonged time in storage, the potency of the vaccine is likely to have declined naturally over time. For this reason, where a vaccine has been given outside of its expiry date, the vaccine will usually need to be repeated. However, contact the vaccine’s manufacturer if this occurs, as they may be able to provide additional information about the shelf-life of their vaccine. If the vaccine needs to be repeated, it should ideally be repeated on the same day. If it cannot be administered on the same day, MMRV vaccine should be repeated 4 weeks after the expired dose was given.

Administration of an additional dose in error

As both MMR and MMRV vaccines are live, there is no additional risk of adverse events from giving additional doses of live vaccine (with the exception of BCG vaccine). The frequency of adverse events following a live vaccine usually falls with the number of doses given as any pre-existing antibodies will neutralise subsequently administered doses of live vaccine viruses. Therefore, parents or carers can be reassured that additional doses are not harmful.  

Administration of an incomplete dose

Where vaccines are administered to patients at less than the recommended dose (for example, if some vaccine spills or leaks out as vaccine is being administered), the vaccine will usually need to be repeated, as the dose the patient received may not be sufficient to evoke a full immune response. The MMRV vaccine should ideally be repeated on the same day. If it cannot be administered on the same day, MMRV vaccine should be repeated 4 weeks after the partial dose was given. This is to avoid the response to the MMR component inhibiting response to the varicella component.

Inadvertent administration of MMRV to a pregnant woman

Pregnant women who are inadvertently vaccinated with varicella-containing vaccine can be reassured. Surveillance over 19 years in the USA did not identify any specific risk to the foetus. No conditions consistent with congenital varicella syndrome have been reported in the UK following vaccination.

If a pregnant individual develops a generalised vesicular (varicella-like) rash following vaccination, they should be clinically reviewed for consideration of antivirals. Local injection site reactions are common and do not require any specific follow up.

UKHSA monitors women who have inadvertently received varicella-containing vaccine up to 1 month before pregnancy or at any time during pregnancy. Women who have been immunised with MMRV vaccine in pregnancy should be reported to UKHSA Vaccine in Pregnancy Surveillance.

Pregnant individuals who are inadvertently vaccinated with MMRV can be reassured with regards to the MMR components. Although MMR-containing vaccines are contraindicated during pregnancy as a precaution, surveillance of inadvertent vaccination in pregnancy has been reassuring.

Inadvertent administration of MMRV to an immunosuppressed individual

Immunosuppressed individuals who are inadvertently vaccinated with MMRV vaccine should be urgently assessed by an appropriate clinician who can establish the degree of immunosuppression. The treatment required will depend on the degree to which the individual is immunosuppressed.

There is further information available on the following webpages:

• post-exposure prophylaxis for chickenpox and shingles

• the National measles guidelines

Reconstitution errors

Inadvertant administration of solvent only

As the solvent is water for injections, it will not provide any protection to the child against measles, mumps, rubella or varicella. If the pre-filled syringe of solvent is given without reconstituting it with the powder containing the vaccine antigens, a new, properly reconstituted vaccine should be prepared and administered as soon as the error is realised. The child’s parents or carers should be reassured that the solvent alone is not harmful but will not protect the child and therefore a second injection with properly prepared vaccine is necessary.

References

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