Every year, the influenza vaccine changes a little bit, incorporating different strains every year.

I believe that these vaccine variants don't have to undergo clinical trials, that they piggyback on the prior influenza vaccine trials. (Right?)

Does that mean that manufacturers of vaccines approved for the COVID-19 Wuhan strain could tweak their process to include the B.1.1.7 and/or P.1 strain without having to go through trials again?

Or do influenza vaccines have a special dispensation somehow?

What are the rules for what you can change in a vaccine without having to go through trials?


1 Answer 1


I found an answer. From https://marginalrevolution.com/marginalrevolution/2021/01/the-new-strain-and-the-need-for-speed.html :

One of the big virtues of mRNA vaccines is that much like switching a bottling plant from Sprite to 7-Up we could tweak the formula and produce a new vaccine using exactly the same manufacturing plants. Moreover, Marks and Hahn at the FDA have said that the FDA would not require new clinical trials for safety and efficacy just smaller, shorter trials for immune response (similarly we don’t do new large-scale clinical trials for every iteration of the flu vaccine.) Thus, if we needed it, we could modify mRNA vaccines (not other types) for a new variant in say 8-12 weeks. As Zeynep notes, however, the vaccines are very likely to work well for the new variant. It’s nice to know, however, that we do have some flexibility.


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