Avian Flu Diary: WHO: Recommended Composition of The 2019 Southern Hemisphere Flu Vaccine

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Twice each year influenza experts from around the world gather to discuss recent developments in human and animal influenza viruses, and to decide on the composition of the next influenza season’s flu vaccine.

Due to the time it takes to manufacture and distribute a vaccine, decisions on which strains to include must be made at least six months in advance, which means the composition of next year's Southern Hemisphere’s vaccine must be decided upon in late September.

As we've discussed before (see The Enigmatic, Problematic H3N2 Influenza Virus), the recent rapid mutation and growing diversity of H3N2 strains has made creating a good vaccine match increasingly more difficult the past few years.

Also, in recent years a new problem with egg-based vaccines has emerged, particularly concerning H3N2 viruses. Tiny changes (mutations) can occur which can affect how well the vaccine recognizes (and protects against) the flu strain it was created from (see PLoS Path.: A Structural Explanation For The Low VE Of Recent H3N2 Vaccines).

While newer manufacturing techniques (cell-based & recombinant) are being phased in, currently most flu vaccines are still produced using the 70 year-old process of taking the selected Candidate Vaccine Virus (CVV) and injecting it into fertilized hen's eggs, and then allowing the virus to replicate for a number of days.

The virus-laden fluid is then harvested from the eggs, and (for flu shots) the viruses are then inactivated (killed), and virus antigen is purified.

While there are some early signs that our Northern Hemisphere may see less H3N2 than last year, we never really know until the season is over. And next year's Southern Hemisphere's flu season is too far off for us to even speculate.

All of which leads us to the announcement from the World Health Organization of their recommendations for next year's Southern Hemisphere Flu shot, which includes a new H3N2 strain.

Recommended composition of influenza virus vaccines for use in the 2019 southern hemisphere influenza season
27 September 2018

It is recommended that egg based quadrivalent vaccines for use in the 2019 southern hemisphere influenza season contain the following:

an A/Michigan/45/2015 (H1N1)pdm09-like virus;

an A/Switzerland/8060/2017 (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 egg based trivalent vaccines for use in the 2019 southern hemisphere influenza season contain the following:

an A/Michigan/45/2015 (H1N1)pdm09-like virus;

an A/Switzerland/8060/2017 (H3N2)-like virus; and

a B/Colorado/06/2017-like virus (B/Victoria/2/87 lineage).

It is recommended that the A(H3N2) component of non-egg based vaccines for use in the 2019 southern hemisphere influenza season be an A/Singapore/INFMH-16-0019/2016-like virus together with the other vaccine components as indicated above.