Guidance

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

Updated 15 January 2026

Who this guidance is for

This guidance is for clinical and public health professionals to assist with the management of an avian influenza human spillover case and their contacts. Avian influenza human spillover infections are acquired following exposure to infected birds or other animals.

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

Clinical and public health professionals should use this guidance for the management of sporadic cases and their contacts. It should not be used in situations where evidence indicates a virus capable of 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.

When to suspect an avian influenza human infection

Consider an avian influenza infection when a patient presents with either: 

• any one or more of the relevant signs and symptoms  

or

• any severe infectious illness that does not have a plausible alternative explanation

and, in addition, either:

close contact (within 1 metre) with one or more of the following in the 14 days before the onset of symptoms:

• any animal, including birds, suspected or confirmed as having avian influenza including in infected premises and/or live bird markets in an area of the world (including within the UK) affected by avian influenza
• secretions from infected animals (respiratory secretions, faeces, unprocessed animal products such as unpasteurised milk)

or

close contact with one or more of the following in the 14 days before the onset of symptoms

• a confirmed human case of avian influenza or their infectious secretions
• human cases of unexplained illness resulting in death from affected areas
• human cases of severe unexplained respiratory illness from affected areas

Signs and symptoms

Signs and symptoms compatible with avian influenza human infection may include one or more of:

• acute uncomplicated upper respiratory tract signs and symptoms also referred to as ILI (fever at or above 37.8°C plus cough or sore throat)
• fever or feeling feverish
• cough
• sore throat
• runny or stuffy nose
• muscle or body aches
• headaches
• fatigue
• eye redness (or conjunctivitis)
• shortness of breath or difficulty breathing

Less common signs and symptoms include:

• diarrhoea
• nausea
• vomiting
• seizures
• other severe or life-threatening illness suggestive of an infectious disease process such as multi-organ failure or meningoencephalitis

It is important to remember that infection with influenza viruses, including avian influenza A viruses, does not always cause fever.

Affected areas

Check the UKHSA list of HCID country-specific risks. If you need advice, email the UKHSA TARZET Acute Respiratory Team at acute.respiratory@ukhsa.gov.uk in hours or contact the Epidemic and Emerging Infections (EEI) consultant on-call (out of hours details circulated with the UKHSA Out of Hours rota) for support, or where consensus cannot be reached locally.

Close contact

Close contact with a human case may include one or more of the following, that occurs during the period 2 days prior to symptom onset or positive virological detection:

• handling laboratory specimens from cases without appropriate precautions
• being within 1 metre distance of the case
• directly providing care
• touching a case
• being within close vicinity of an aerosol generating procedure for a case

What to do when you suspect an avian influenza human infection

For a suspected avian influenza human spillover case, clinicians should manage the patient as a high consequence infectious disease (HCID) case until proven otherwise. The clinical team should carry out the initial assessment in strict accordance with the Trust’s established HCID Assessment Pathway Protocol.

Use infection prevention and control (IPC) measures as set out in the NHS National Infection Prevention and Control Manual (NIPCM). Use personal protective equipment (PPE) according to the addendum on HCID PPE.

Notify any suspected avian influenza case to the local  UKHSA health protection team by phone within 24 hours. Influenza of zoonotic origin is an urgent notifiable disease.

Before you carry out an in-person clinical assessment:

• isolate the patient in a single occupancy room, preferably a respiratory isolation room and ideally under negative pressure; positive pressure rooms must not be used
• minimise patient contact with staff and other patients and ask the patient to wear a surgical mask when outside the room
• ensure transmission-based-precautions and enhanced PPE (including donning and doffing procedures), as outlined in the NIPCM addendum on HCID PPE
• start oseltamivir treatment as per the British National Formulary (BNF)

Clinical assessment, treatment and isolation

Clinical assessment should be carried out for suspected avian influenza human spillover cases, as well as symptomatic contacts of confirmed and probable cases. HPTs should:

• request clinical assessment by the NHS
• arrange testing for avian influenza
• complete the Zoonotic Influenza Enhanced Surveillance Questionnaire and send to  acute.respiratory@ukhsa.gov.uk

Clinical assessment will depend on the patient’s condition and local protocols for assessing and swabbing possible HCID cases. Acutely unwell individuals should be assessed in an acute hospital setting using local protocols.

Individuals who do not require hospital care may be assessed in a community setting, in line with local protocols. Local systems should provide an appropriate clinician, assessment space, and PPE. Virtual triage may be acceptable before referral for in-person clinical assessment.

Isolation

Clinical and public health professionals should:

• advise patients at home who are awaiting transfer for clinical assessment or test results to isolate away from household members
• inform the IPC team at the accepting Trust and the ambulance service about the suspected avian influenza case before transfer
• advise patients to self-isolate until they receive a negative avian influenza test result

Antiviral use

Clinical staff should:

• initiate oseltamivir treatment for the case as per the BNF
• initiate antivirals as soon as possible, ideally within 48 hours, but treatment can be started up to 7 days from last exposure

Testing protocol

Clinical and public health professionals should use the Diagnostic Testing for Avian Influenza A(H5) and Other Zoonotic Influenza Viruses guidance.

If the initial test is negative for avian influenza and the individual develops new symptoms within the 14 days following exposure, repeat the test.

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. UKHSA regional labs or NHS labs are only able to detect avian influenza A(H5) subtypes. These presumptive positive results will need to be confirmed by RVU.

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

For guidance on clinical assessment, see Clinical assessment.

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.

Public health actions

Clinical and public health professionals should advise confirmed cases:

• to self-isolate for 14 days from onset
• to avoid contact with farm animals (including poultry) during the isolation period
• to postpone any non-essential medical or dental treatment during the isolation period
• to inform the healthcare provider if essential treatment is required
• to postpone international travel for 14 days from onset

HPTs should:

• complete the Zoonotic Influenza Enhanced Surveillance Questionnaire and send to acute.respiratory@ukhsa.gov.uk
• initiate contact tracing and manage contacts

The Incident Management Team (IMT) should activate the First Few X (FFX) cases protocol and report the confirmed case to the World Health Organization (WHO) within 24 hours of confirmation via the national focal point (IHRNFP@ukhsa.gov.uk).

Antiviral treatment

Clinical staff should initiate oseltamivir treatment for the case as per the BNF.

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 clinically well enough for safe discharge as judged by the clinical team managing the patient
• the patient is 14 days post onset of symptoms and is continuing to clinically improve (or symptoms have resolved)
• 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 speak 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.

Clinical and public health professionals should advise individuals self-isolating at home to: 

• 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

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. They should not be used by clinicians to determine which individuals should be assessed for clinical diagnostic testing.

Possible case

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

• has had any high or low-risk exposure to a confirmed or probable avian influenza human spillover case in the 14 days before symptom onset (see What to do with individuals exposed to an avian influenza human spillover case)
• 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 or probable avian influenza human spillover case in the 14 days before symptom onset (see What to do with individuals exposed to an avian influenza human spillover case)
• has any clinical presentation (symptomatic or asymptomatic)
• has influenza A positive results but un-subtypable 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 NHS labs are only able to detect avian influenza A H5 subtypes. Presumptive positive results from these labs need to be confirmed by RVU.

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 an avian influenza human spillover case
• monitor contacts
• arrange clinical assessment and testing for contacts who develop symptoms within the 14 days from the last exposure

Contact tracing for any confirmed or probable case of avian influenza. 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 by their exposure risk and manage them according to the information below.

High risk exposure

Exposure is considered high risk when contact to a confirmed or probable avian influenza human spillover case is close or 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 within 1 metre for at least 15 mins
• 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 (within 1m) for any duration
• direct clinical or personal care, or 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

1. 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 chemoprophylaxis
• arrange for testing through First Few Cases (FFX) study

If the contact develops symptoms during the active monitoring period:

• arrange immediate clinical assessment and diagnostic testing
• recommend antiviral treatment
• advise them to self-isolate for 14 days following onset of symptoms

2. 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
• 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 chemoprophylaxis

If the contact develops symptoms during the active monitoring period:

• arrange immediate clinical assessment and diagnostic testing
• recommend antiviral treatment
• 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

Chemoprophylaxis

Chemoprophylaxis 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 [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 is 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 to a confirmed or probable avian influenza human spillover case is protected, indirect, or brief.

Example scenarios

1. Shared space with the case, maintaining over a 1 metre distance

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 (within 1m) for any duration
• direct clinical or personal care or 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
• 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
• advise contacts to self‑isolate until a negative avian influenza test result is available, either for the index case or the contact