Guidance

Managing sporadic avian influenza human spillover cases and their contacts in England

Updated 28 October 2026

Who this guidance is for

This guidance is for clinical and health protection professionals to assist with the management of a confirmed avian influenza human spillover case and their contacts. Avian influenza human spillover infections are acquired following exposure to infected birds or other animals. For guidance on when to suspect an avian influenza human infection, including clinical assessment and testing, please use Guidance for the management of people exposed to birds or other animals infected with avian influenza.

Find out more on what bird flu is and how we are protecting people against it in the UK.

Clinical and health protection professionals should use this guidance for the management of sporadic cases and their contacts. It should not be used in situations where evidence indicates that a virus is capable of even limited human-to-human transmission.

Personal protective equipment (PPE) requirements are set out in the National Infection Prevention and Control Manual (NIPCM) for England. Use the addendum on HCID PPE for guidance.

How to manage confirmed avian influenza human cases

A confirmed case is defined as an individual (alive or deceased), with a positive avian influenza subtype result confirmed by the UKHSA Respiratory Virus Unit (RVU) in any clinical sample. Laboratory investigations, sample transfer instructions including roles for the UKHSA duty doctor microbiologist or virologist, RVU, EEI Consultant and the HPT are outlined in Diagnostic testing for avian influenza A(H5) and other zoonotic influenza viruses.

Primary diagnostic testing of samples from patients with suspected avian influenza should be via the UKHSA Clinical Network Laboratories (CNLs). The CNLs undertake influenza A typing and avian influenza H5 subtyping, as well as seasonal H1/H3 subtyping PCR test. Influenza A viruses evolve continuously therefore CNL tests are regularly assured for diagnostic capability. 

A negative influenza A test alone, obtained in a local NHS laboratory may not exclude zoonotic influenza in a suspected case with relevant exposure history. Influenza A positive unsubtypable samples should be referred to the RVU for further characterisation.

An H5 positive detection in a CNL lab is considered a presumptive positive, and results will need to be confirmed by RVU.

All presumptive positive and confirmed avian influenza cases should be admitted to an HCID unit for further assessment and management.

Antiviral treatment

Clinical staff should initiate oseltamivir treatment for the case as per the British National Formulary (BNF).

Testing protocol

Clinical staff should obtain baseline serology where possible on or as close to day 0 as possible and then between day 21 and 35 and send to UKHSA RVU.

Isolation

Clinical and health protection professionals should advise confirmed cases to self-isolate for 14 days from onset, however, the individual may be released from self-isolation if they have tested negative on the day 10 swab and symptoms have resolved. Individuals that have been discharged from an HCID unit, but still self-isolating at home should:

• self-isolate in private accommodation, unless an alternative has been agreed with UKHSA
• avoid contact with other household members
• not share towels, bed linen, toothbrushes or eating and drinking utensils, such as cutlery or cups
• not go to work, school or public areas
• avoid contact with animals wherever possible
• postpone any non-essential medical or dental procedures requiring attendance at a healthcare setting
• inform the healthcare provider that they have avian influenza, if essential treatment is required
• postpone domestic and international travel

Health Protection Teams (HPTs) should:

• complete the Zoonotic Influenza Enhanced Surveillance Questionnaire CIMS Wizard and send a brief email with the CIMS number to acute.respiratory@ukhsa.gov.uk
• initiate contact tracing and manage contacts
• set up an Incident Management Team (IMT)

The IMT should:

• report the confirmed case to the World Health Organization (WHO) within 24 hours of confirmation via the national focal point (IHRNFP@ukhsa.gov.uk)
• arrange for testing of the confirmed case and their contacts on days 0, 5 and 10. A sporadic human case with unknown exposure would activate the First Few X (FFX) cases protocol

Hospital de-isolation criteria for confirmed cases

De-isolation arrangements for individual patients should be considered on a case-by-case basis.

De-isolation of an avian influenza confirmed case is based on the clinical presentation and the correct interpretation of the laboratory findings. De-isolation can be considered if:

• the patient is 14 days post onset of symptoms and is continuing to clinically improve (or symptoms have resolved) AND
• the patient is clinically well enough for safe discharge as judged by the clinical team managing the patient OR
• the patient may be released from self-isolation if they have tested negative on the day 10 swab and symptoms have resolved

Patients judged to be clinically well enough for a safe discharge but not meeting the laboratory criteria may be discharged from hospital. The treating clinician should discuss the discharge plans with the HPT and the HCID network before the patient is released. The patient should continue to isolate at home for 14 days from the onset of their symptoms.

What to do with individuals exposed to an avian influenza human spillover case

It is a public health responsibility:

• to identify, assess and categorise contacts of a confirmed avian influenza human spillover case
• to monitor contacts
• to arrange clinical assessment and testing for contacts who develop symptoms within the 14 days from the last exposure, this should follow processes laid out in Guidance for the management of people exposed to birds or other animals infected with avian influenza and Diagnostic testing for avian influenza A(H5) and other zoonotic influenza viruses.

Case definitions

This section provides case definitions to support health protection teams (HPTs) with the public health management of symptomatic individuals who have been exposed to an avian influenza human spillover case.

Possible case

A possible case is an individual who (all of the following):

• has had any high or low-risk exposure to a confirmed avian influenza human spillover case in the 14 days before symptom onset
• has influenza-like illness (ILI) or conjunctivitis or any severe infectious illness that does not have a plausible alternative explanation
• has not yet been tested for influenza A or is pending a test result

Probable case

A probable case is an individual who (all of the following):

• has had any high or low-risk exposure to a confirmed avian influenza human spillover case in the 14 days before symptom onset
• has any clinical presentation (symptomatic or asymptomatic)
• has influenza A positive results but unsubtypable or subtype unavailable in local PCR assays

Confirmed case

A confirmed case (alive or deceased) is an individual with a positive avian influenza subtype (for example, A(H5N1)) result confirmed by the UKHSA Respiratory Virus Unit (RVU) in any clinical sample.

UKHSA regional labs and some NHS labs are only able to detect avian influenza A H5 subtypes, these presumptive positive results need to be confirmed by RVU.

Contact tracing should be undertaken for any confirmed or probable case, as per the case definitions above. A contact is an individual who has had exposure to a case (as per the table below) during the period −2 to +14 days of symptoms. Day 0 is the first day of symptoms, or for asymptomatic cases day 0 is the day of the first positive test. Any individual who has not had contact with the case within the last 14 days is not deemed to be a contact.

Management of individuals exposed to an avian influenza human spillover case

HPTs should assess all individuals exposed to confirmed or probable human cases (or their infectious secretions) by their exposure risk and manage them according to the information below.

High risk exposure

Exposure is considered high risk when contact with a case is close, direct and unprotected.

Example scenarios

1. Household contact, including staying in the same accommodation overnight or using shared facilities or living spaces

2. Close contact:

• any direct or face-to-face contact indoors or outdoors
• direct contact with infectious secretions or contaminated environment for example, as a caregiver without appropriate PPE
• passengers in the same car
• passengers in a large, shared vehicle (for example, plane or bus) seated within 2 seats in all directions of the case, or crew members serving the same compartment
• other close contact based on risk assessment by the HPT

3. Health or social care worker with any of the following types of contact, without appropriate PPE or with a PPE breach:

• any direct or face-to-face contact
• direct clinical or personal care, including examination
• direct contact with infectious secretions
• in the same room as an aerosol generating procedure (AGP)

4. Laboratory staff exposed to samples with a breach in safety procedures or PPE (refer to local laboratory code of practice and risk assessment

Actions to take

If the contact has had high risk exposure to a confirmed case, HPTs should:

• inform the contact about the risk
• provide active monitoring information leaflet
• carry out active monitoring for 14 days following last exposure
• advise contact to self-isolate for 14 days following last exposure
• recommend post-exposure prophylaxis
• arrange for 2 upper respiratory tract samples on days 0, 5 and 10 using the Diagnostic testing for avian influenza A(H5) and other zoonotic influenza viruses guidance.

If the contact develops symptoms during the active monitoring period:

• arrange immediate clinical assessment and diagnostic testing
• recommend antiviral treatment as per the BNF
• advise them to self-isolate for 14 days following onset of symptoms or until a negative avian influenza test result is available, they will still need to complete the 14 days of isolation following last exposure to the confirmed case
• if new clinical symptoms develop within 14 days of last exposure, re-test

If the contact has had high risk exposure to a probable case, HPTs should:

• inform the contact about the risk
• provide active monitoring information leaflet
• carry out active monitoring for 14 days following last exposure or until a negative avian influenza test result is available for the index case
• advise contact that they may continue with normal activities
• conduct risk assessment for individuals working with clinically vulnerable populations
• liaise with IHR team for contacts planning international travel
• recommend post-exposure prophylaxis

If the contact develops symptoms during the active monitoring period:

• arrange immediate clinical assessment and diagnostic testing
• recommend antiviral treatment as per the BNF
• advise contacts who develop symptoms to self‑isolate until a negative avian influenza test result is available, either for the index case or the contact
• if new clinical symptoms develop within 14 days of last exposure, re-test

Post-exposure prophylaxis for high-risk contacts:

1. Initiate as soon as possible (ideally within 48 hours of their exposure to the case)

2. Use oseltamivir treatment course (75mg twice daily for 5 days with dose adjustment where appropriate - see below [note 1])

Note 1. This recommendation is based on limited data that support higher chemoprophylaxis dosing for avian influenza A infection. It aims to reduce the potential for the development of antiviral resistance from receiving once daily chemoprophylaxis.

Antivirals can be started up to 7 days after the last exposure but are likely to be less effective if delayed; rapid access to antivirals should be a priority. For additional guidance on dosage recommendations, such as for those with renal impairment or treatment by age group, see Patient Group Direction (PGD) for the supply of oseltamivir for pre and post exposure of avian influenza .

Low risk exposure

Exposure is considered low risk when contact is protected, indirect, or brief.

Example scenarios

1. Shared space with the case, but not face-to-face

2. Passengers in a large, shared vehicle/plane who are seated more than 2 seats in all directions from the case, and crew members not serving the same compartment

3. Health or social care worker with any of the following types of contact using the appropriate PPE and no breaches in use:

• any direct or face-to-face contact
• direct clinical or personal care, including examination
• in the same room as an (AGP)

4. Laboratory staff exposed to samples without any breaches in safety procedures or PPE (refer to local laboratory code of practice and risk assessment)

Actions to take

1. If the contact has had low risk exposure to a confirmed case, HPTs should:

• inform contact about the risk
• provide active monitoring information leaflet
• carry out active monitoring for 14 days following last exposure

If the contact develops symptoms during the active monitoring period:

• arrange immediate clinical assessment and diagnostic testing
• recommend antiviral treatment as per the BNF
• advise contacts to self‑isolate until a negative avian influenza test result is available

2. If the contact has had low risk exposure to a probable case, HPTs should:

• inform contact about the risk
• provide passive monitoring information leaflet
• carry out passive monitoring for 14 days following last exposure

If the contact develops symptoms during the passive monitoring period:

• arrange immediate clinical assessment and diagnostic testing
• recommend antiviral treatment as per the BNF
• advise contacts to self‑isolate until a negative avian influenza test result is available, either for the index case or the contact

The IMT should activate the FFX study if a contact of avian influenza human spillover case tests positive for any avian influenza subtype confirmed by the UKHSA Respiratory Virus Unit (RVU) in any clinical sample.