Positive symptomatic influenza cases:

1. Must be transferred into a side room with the appropriate source isolation with respiratory precautions.
2. Must be assessed for treatment with antivirals (Guidelines for the Clinical Management of Adult patients with Influenza).
3. Can discontinue isolation:
   1. in adults 7 days from symptom onset or 5 days from start of antivirals
   2. in children 7 days from symptom onset or until no symptoms whichever is longer
   3. in immunosuppressed 7 days from symptom onset or until no symptoms whichever is longer

Exposed patients:

Assess all exposed patients for symptoms of influenza, this includes bay contacts and other patients who have been exposed ≤48 hours prior to the index case’s positive test:

1. Exposed patients who are exhibiting flu like symptoms must have a LIAT POC test and be source isolated. Medical staff should refer to current National Influenza Guidance for treatment recommendations. If LIAT POC result is ‘Not Detected’ for influenza and COVID-19, please send nose & throat swab to laboratory for extended viral respiratory PCR testing.
2. Asymptomatic exposed patients who have last been in contact with the index case less than 48 hours ago should be considered for antiviral prophylaxis as per National Influenza Guidance. If prescribed, please send a nose & throat swab to the laboratory for viral respiratory PCR testing to determine influenza status, this is required to ascertain the correct dose and duration of anti-viral therapy.
3. Asymptomatic exposed patients who have last been in contact with the index case greater than 48 hours ago, but less than 96 hours ago, and who are assessed as at high-risk for complicated influenza should be prescribed antivirals at treatment dose. Send a nose & throat swab to the laboratory for viral respiratory PCR testing to determine influenza status.
4. If a single case of flu is detected in a bay, once the index case has been isolated, the bay can stay open provided all contacts have been clinically assessed and symptomatic patients have tested negative for flu. If two or more cases of flu occur in the same bay, the bay should close for a minimum of 4 days.
5. All patients exposed to influenza must be monitored for symptoms for 4 days from last day of contact by the medical and nursing teams in the ward environment, regardless of anti-viral use, bed placement or vaccination status.
6. Vaccinated and/or unvaccinated individuals flu contacts, including any who remain in a bay, should be monitored closely for symptoms for 4 days. If this is not possible, please escalate to the infection control team or clinical site manager.
7. Ward environments must inform the Infection Prevention team at the earliest opportunity should a formerly exposed patient develop symptoms of influenza.

NB Contact tracing and assessment for prophylaxis. The IPC team will support clinical teams to identify influenza contacts. It is not usually feasible to look back beyond 48 hours prior to the date of the first flu test but risk assessment will be employed. Clinical teams are asked to use this guidance to assess patients who have been identified as flu contacts.

Identified strain in index case or dominant circulating strain is lower risk for oseltamivir resistance (influenza A (H3N2), influenza B)

Identified strain in index case or dominant circulating strain is higher risk for oseltamivir resistance (influenza A (H1N1)pdm09)

Exposed to suspected or confirmed oseltamivir resistant influenza

Previously healthy

No prophylaxis

No prophylaxis

No prophylaxis

At risk of complicated influenza (excluding severely immunosuppressed patients and children under 5 years).

Oseltamivir PO once daily for 10 days

Oseltamivir PO once daily for 10 days

Zanamivir INH once daily for 10 days, if therapy can be started within 36 hours of last exposure; or after 36 hours on specialist advice.

Severely immunosuppressed patients (excluding children under 5 years).

Oseltamivir PO once daily for 10 days

Zanamivir INH once daily for 10 days, if therapy can be started within 36 hours of last exposure; or after 36 hours on specialist advice.
If unable to administer zanamivir INH, oseltamivir PO once daily for 10 days.

Zanamivir INH once daily for 10 days, only if therapy can be started within 36 hours of last exposure; or after 36 hours on specialist advice.
If unable to administer zanamivir INH, monitor closely and begin treatment promptly if ILI symptoms develop

Children under 5 years in at risk groups including severely immunocompromised children

Oseltamivir PO once daily for 10 days

Oseltamivir PO once daily for 10 days

Monitor closely and begin treatment promptly if ILI symptoms develop.

Prophylaxis

Premature

(less than 36 weeks post conceptional age)

Infants under 12 months

(36 weeks post conceptional age or greater)

Children 1 to 12 years:

Dose according to weight below

Adults

(13 years and over)2

Less than or equal to 15kg

More than 15 to 23 kg

More than 23 to 40 kg

More than 40kg

Oseltamivir PO (prophylaxis course 10 days)

See below1

3mg/kg od

30mg od

45mg od

60mg od

75mg od

75mg od

Zanamivir INH (prophylaxis course 10 days)

Not licensed for children under 5 years old.
Adults and children equal or greater than 5 years old 10mg od

10mg od

Figure 2 Definitions and at risk groups

• Index case = Patient with influenza A or B
• Symptoms of influenza =
  1. Fever (38ºC or above) or history of fever 
  2. Two or more of the following symptoms: cough, sore throat, headache, rhinorrhoea, myalgia, coryza, diarrhoea or vomiting (counts as one symptom)
• Symptomatic = symptoms of influenza.
• Asymptomatic = patient does not have symptoms of influenza
• POC = Point of Care
• At risk groups (at risk of complicated influenza):
  • neurological, hepatic, renal, pulmonary and chronic cardiac disease
  • diabetes mellitus
  • severe immunosuppression
  • age over 65 years
  • pregnancy (including up to 2 weeks post-partum)
  • morbid obesity (BMI ≥40)

Respiratory precautions:

• Single use gloves and apron
• Surgical face mask
• FFP3 and long sleeve gown for aerosol generating procedures