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In the UK, we are offering two #CovidVaccine bivalent #boosters
Pfizer was tested on 305 people, plus 315 who got an Omicron-only boost
Moderna was tested on 437 people, vs 377 boosted with the old version
Weren’t the original vaccines tested on tens of thousands of people? Why have the boosters only been tested on hundreds? 2/
The original trials were the first large-scale trials of the mRNA platform. We needed lots of participants to ensure we could find unexpected side effects. We now have a good understanding of the platform, so we can confirm safety for the tweaked boosters on smaller numbers. 3/
The original trials needed to prove efficacy, and quickly! For that we needed large numbers. Now we understand – from the original trials – what a protective immune response looks like, for the boosters we are just looking for evidence of a good immune response. 4/
The extensive work done confirming safety and efficacy in the original large trials, plus all the extra data we’ve collected during the rollout, allow us to test booster on fewer people. This is very similar to how we update the flu vaccine every year. 5/
Bonus for anyone who is #pregnant or #breastfeeding…
The bivalent approval documents specifically say that you can have the #CovidVaccine bivalent #Booster /6
Bonus for immunology nerds Can we assume there will be no adaptive immune-mediated problems specific to the tweaked antigen? 7/
The Ag are very similar, but theoretically this could happen. However, since it would be MHC restricted, it would likely to occur in fewer than 1 in 100,000 ppl – rare enough that we could only ever detect it in the general rollout, no matter how big we made the trials. 8/8
PS. As a general rule I keep replies on because I want to be able to respond to genuine questions – and we had some of those last night. Waking up this morning to a lot of questions that I suspect are not asked in good faith, so switching them off temporarily. Happy weekend
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weehingthong 