INFLUENZA IMMUNISATION

Prevention of influenza is important and in October and November each year, UK general practices deliver a programme of vaccination against seasonal influenza to at-risk groups. Vaccine is prepared annually from the three or four  strains of the virus thought most likely to be circulating.

Each year the World Health Organization (WHO) determines the components of the annual seasonal influenza vaccine, based on surveillance of circulating virus types

WHO recommends that quadrivalent vaccines for use in the 2021-2022 northern hemisphere influenza season contain the following:

Egg-based vaccines

• An A/Victoria/2570/2019 (H1N1)pdm09-like virus;
• An A/Cambodia/e0826360/2020 (H3N2)-like virus;
• A B/Washington/02/2019 (B/Victoria lineage)-like virus; and
• A B/Phuket/3073/2013 (B/Yamagata lineage)-like virus.

Cell- or recombinant-based vaccines

• An A/Wisconsin/588/2019 (H1N1)pdm09-like virus;
• An A/Cambodia/e0826360/2020 (H3N2)-like virus;
• A B/Washington/02/2019 (B/Victoria lineage)-like virus; and
• A B/Phuket/3073/2013 (B/Yamagata lineage)-like virus.

WHO recommends that trivalent influenza vaccines for use in the 2021-2022 northern hemisphere influenza season contain the following:

Egg-based vaccines

• An A/Victoria/2570/2019 (H1N1)pdm09-like virus;
• An A/Cambodia/e0826360/2020 (H3N2)-like virus; and
• A B/Washington/02/2019 (B/Victoria lineage)-like virus.

Cell- or recombinant-based vaccines

• An A/Wisconsin/588/2019 (H1N1)pdm09-like virus;
• An A/Cambodia/e0826360/2020 (H3N2)-like virus; and
• A B/Washington/02/2019 (B/Victoria lineage)-like virus.

Only suitably trained healthcare professionals should give vaccinations.

Indications for influenza vaccine

Age 65 years and older, and anyone aged 6 months–65 years in a clinical risk group 

• • Chronic respiratory disease
  • Chronic heart disease
  • Chronic kidney disease
  • Chronic neurological disease
  • Chronic liver disease
  • Diabetes mellitus
  • Immunosuppression
  • Asplenia or splenic dysfunction
  • Obesity
  • People in long-stay residential, nursing or care facilities
  • People receiving a carer's allowance
  • Pregnant women
  • All healthcare and social care workers 

In addition, children aged 2-17 years should be vaccinated as part of the national programme to reduce community transmission.

Recommended vaccines

• Adults aged 65 years and older: adjuvanted trivalent influenza vaccine (aTIV), or cell-based quadrivalent influenza vaccine (QIVc)
• Aged 18–64: QIVc or egg-grown quadrivalent influenza vaccine (QIVe)
• Children aged 2-17 years in a clinical risk group or as part of national programe: quadrivalent live attenuated influenza vaccine (LAIV)
• Children aged 6 months to less than 2 years: QIV

Vaccination is approximately 70% effective, depending on the degree of matching between the vaccine composition and the types of influenza in circulation; protection lasts for 1 year. See also Influenza in Infectious diseases