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?