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03 Apr 2019

WHO influenza vaccine Northern Hemisphere recommendations

Each year the World Health Organisation (WHO) provides a recommendation as to which influenza strains should be incorporated into the flu vaccine for both the Northern and Southern Hemisphere. We spoke with the WHO Collaborating Centre for Reference and Research on Influenza, located at the Doherty Institute, about the consultation process and why the decision for the Northern Hemisphere's recommendations was delayed this year. 

What is the WHO Influenza Vaccine Consultation all about?

The World Health Organisation (WHO) holds a Consultation at which WHO and influenza experts from around the world advise on which influenza viruses should be included in the vaccine, approximately 6-9 months for the upcoming influenza season. The Consultation is held twice a year - in February prior to the upcoming season in the Northern Hemisphere (NH) for countries with an influenza seasonality similar to the temperate parts of the NH, and in September in the year prior to the upcoming season in the Southern Hemisphere (SH) for countries with an influenza seasonality similar to the temperate parts of the SH.

If the recent Consultation was for the Northern Hemisphere winter, why is the Centre at the Doherty Institute in Melbourne involved?

Although the most recent Consultation recommended the vaccine composition for the upcoming Northern Hemisphere influenza season in 2019-2020, The WHO Collaborating Centre for Reference and Research on Influenza at the Doherty Institute provides data on recently circulating viruses from countries in our geographical region that have influenza cases from September-January each year. In addition, Australia had an extended influenza season in 2018  and a significant number of “Summer flu” cases in 2018-9 which provided many recent Australian viruses to analyse. Our data are combined with data from with the four other WHO Collaborating Centres for Influenza (all based in the northern hemisphere in Atlanta, Beijing, London and Tokyo), to characterise recently circulating influenza viruses and predict which vaccine candidates will provide the best protection in the upcoming season.

The WHO Collaborating Centres for Influenza also identify and process candidate viruses that could possibly be used in the vaccine. In the recent Consultation, the A(H1N1)pdm09 virus that was newly selected for inclusion in the Northern Hemisphere influenza vaccine  in 2019-2020 (A/Brisbane/02/2018) was originally isolated in eggs at our Centre in Melbourne.

What was decided for this Consultation?

Following the WHO Consultation on the Composition of Influenza Vaccines for the Northern Hemisphere 2019-2020 in Beijing, China on 18-20 February 2019, the WHO made the following recommendation:

It is recommended that egg based quadrivalent vaccines for use in the 2019-2020 influenza season (northern hemisphere winter) contain the following:

  •  an A/Brisbane/02/2018 (H1N1)pdm09-like virus*;
  •  an A/Kansas/14/2017 (H3N2)-like virus**;
  •  a B/Colorado/06/2017-like virus (B/Victoria/2/87 lineage); and
  •  a B/Phuket/3073/2013-like virus* (B/Yamagata/16/88 lineage).

It is recommended that the influenza B virus component of trivalent vaccines for use in the 2019-2020 northern hemisphere influenza season be a B/Colorado/06/2017-like virus of the B/Victoria/2/87-lineage.

It is recommended that the influenza B virus component of trivalent vaccines for use in the 2019-2020 northern hemisphere influenza season be a B/Colorado/06/2017-like virus of the B/Victoria/2/87-lineage.

* viruses originating from isolates generated at the Melbourne WHO CC

**recommendation made on 21 March, 2019

In what ways is the WHO recommendation significant?

The recommendation includes a change in the A(H1N1)pdm09 component of the egg and cell-based vaccines. The change was made based on testing that showed that people who had received the influenza vaccine in 2018 had reduced serum antibody responses to recently circulating A(H1N1)pdm09 viruses.

After a one-month delay, the recommendation for the A(H3N2) component of the vaccine was also changed, due to differences in the antigenic properties of recently circulating viruses compared to the previous A(H3N2) vaccine strain.

Why was the decision on the A(H3N2) component delayed?

The most recent WHO Consultation was held in February, however the selection of the A(H3N2) component to include in the vaccine was delayed until March. This delay is very unusual and has only happened once in the previous 20 years.  The delay was due to the rise in the proportion of one group of A(H3N2) viruses circulating in the USA and some European countries. Postponing the recommendation enabled more time to monitor circulating viruses and characterise potential vaccine candidates.

Will this affect the Southern Hemisphere influenza vaccine this year?

No. The WHO recommendations for the Southern Hemisphere influenza vaccine for 2019 were made in September 2018. Vaccines have already been produced and will be available in April 2019.

More information can be found at: https://www.who.int/influenza/vaccines/virus/recommendations/2019_20_north/en/

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