This made for an interesting VRBPAC meeting last month for deciding on what strains to use for next year's Flu season. Normally the WHO's Global Influenza Surveillance and Response System peaks at about 50k positive influenza specimens in a week. This past season we peaked at about 300, and not for lack of testing.
In some cases, for a couple lineages there was only one clade of that lineage circulating globally. This may make the 2021-2022 Flu vaccine fairly efficacious. On the other hand, with so little Flu circulating it was hard to determine what strains are likely to dominate next season.
There was so little Flu circulating, they had insufficient data to determine the vaccine efficacy for the 2020-2021 season.
The VRBPAC meeting for the Flu vaccine last month:
I'll be curious what we see going forward after we start changing behaviors and policies. Personally I think travel restrictions were a big factor in the Flu decrease, so I think next year's Flu could come roaring back. But I will be really interested in seeing if vaccination rates stay high. We saw a lot of people not used to getting the Flu vaccine get it this pandemic. And we saw amazing uptake among the elderly. And I'm generally pessimistic on behavior change durability after the pandemic, but masks and norms around symptomatic illness I think could be somewhat durable. I think people will have a lot less patience for their co worker with "just the sniffles".
I can't wait to see though most of all what the mRNA vaccine tech will do to the Flu vaccine. The Flu vaccine efficacy is like 25-50% depending on the strain and season. It would be fantastic if we managed to produce a Flu vaccine that was as efficacious as the coronavirus vaccines. The mRNA breakthrough could manage that. When the Flu vaccine manages to accurately target a strain it tends to be very effective, we just often end up missing the right strain because the strains are chosen based off of circulation going on 6-12 months before the season.