I've seen news stories (such as this one) claiming that the 2017-2018 flu vaccine is not a "good match" to circulating influenza viruses. However, the CDC states:

Two hundred sixty-two influenza A(H3N2) viruses were antigenically characterized, and 257 (98.1%) A(H3N2) viruses tested were well-inhibited (reacting at titers that were within fourfold of the homologous virus titer) by ferret antisera raised against A/Michigan/15/2014 (3C.2a), a cell propagated A/Hong Kong/4801/2014-like reference virus representing the A(H3N2) component of 2017–18 Northern Hemisphere influenza vaccines.

Are the news stories wrong?

1 Answer 1


The research into last year's flu season puts the blame on egg-based vaccine production.

Reference: https://www.vox.com/science-and-health/2018/2/1/16960758/flu-vaccine-effectiveness

Researchers guess at the dominant flu strains well before flu season starts, then grow the strains in chicken eggs - an outdated process that takes weeks.

Additionally, H3N2 (influenza A and the dominant strain last year) is infamous for rapid mutation. Often, the dominant strain can mutate after the previously mentioned researchers' guess has been finalized and the vaccine is queued for mass production. Also reported in the Vox article: 33% combined vaccine effectiveness in H3N2 seasons, vs. slightly over 50% when influenza B dominated and 67% in H1N1 (swine flu) seasons.

Another problem the article mentions with growing flu vaccines in chicken eggs: H3N2 viruses mutate to get better at infecting the eggs, which means that even if you guess at the correct strain and grow it in eggs, the output vaccine isn't guaranteed to have the same structure (and therefore won't be as effective as expected).

Why is the industry still using eggs?

2 reasons, again mentioned in the Vox article: The industry is already optimized and built around the egg-based workflow (economy of scale) - and more modern approaches (cell-based and recombinant) are far more expensive. Additionally, more research is needed to determining if the cell-based and recombinant approaches produce a more reliable vaccine.

In a summary answer to your question, it would appear to be "no", due to the egg-based mutation mentioned above. The Vox article also mentions abysmal protection rates in that season's vaccine against the dominant H3N2 strain, as low as 17% reported in Canada.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.