The periodic replacement of virus strains contained in influenza vaccine is necessary because of the constant evolution of influenza viruses, which can change their antigenic and genetic characteristics. The World Health Organization (WHO) recommends the following influenza vaccine composition information.

Northern Hemisphere 2020 – 2021

WHO recommends that quadrivalent vaccines for use in the 2020 - 2021 northern hemisphere influenza season contain the following:

Egg-based Vaccines
•    an A/Guangdong-Maonan/SWL1536/2019 (H1N1)pdm09-like virus;
•    an A/Hong Kong/2671/2019 (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/Hawaii/70/2019 (H1N1)pdm09-like virus;
•    an A/Hong Kong/45/2019 (H3N2)-like virus;
•    a B/Washington/02/2019 (B/Victoria lineage)-like virus; and
•    a B/Phuket/3073/2013 (B/Yamagata lineage)-like virus.

It is recommended that trivalent influenza vaccines for use in the 2020 - 2021 northern hemisphere influenza season contain the following:

Egg-based Vaccines
•    an A/Guangdong-Maonan/SWL1536/2019 (H1N1)pdm09-like virus;
•    an A/Hong Kong/2671/2019 (H3N2)-like virus; and
•    a B/Washington/02/2019 (B/Victoria lineage)-like virus.

Cell- or recombinant-based Vaccines
•    an A/Hawaii/70/2019 (H1N1)pdm09-like virus;
•    an A/Hong Kong/45/2019 (H3N2)-like virus; and
•    a B/Washington/02/2019 (B/Victoria lineage)-like virus.

More information
WHO (February 2020) Recommended composition of influenza virus vaccines for use in the 2020 - 2021 northern hemisphere influenza season - full report    
WHO (February 2020) Frequently Asked Questions
WHO (February 2020) Candidate vaccine viruses and potency testing reagents for development and production of vaccines for use in the northern hemisphere 2020-21 influenza season


Southern Hemisphere 2021

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

Egg-based Vaccines
•    an A/Victoria/2570/2019 (H1N1)pdm09-like virus;
•    an A/Hong Kong/2671/2019 (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/Hong Kong/45/2019 (H3N2)-like virus;
•    a B/Washington/02/2019 (B/Victoria lineage)-like virus; and
•    a B/Phuket/3073/2013 (B/Yamagata lineage)-like virus.

It is recommended that trivalent influenza vaccines for use in the 2021 southern hemisphere influenza season contain the following:

Egg-based Vaccines
•    an A/Victoria/2570/2019 (H1N1)pdm09-like virus;
•    an A/Hong Kong/2671/2019 (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/Hong Kong/45/2019 (H3N2)-like virus; and
•    a B/Washington/02/2019 (B/Victoria lineage)-like virus.

More information
•    WHO. (25 September 2020) Recommended composition of influenza virus vaccines for use in the 2021 southern hemisphere influenza season - full report
•   WHO. (25 September 2020) Frequently Asked Questions

 

(Updated 28 September 2020)