Why you can’t compare Covid-19 vaccines
In the US, the first two available Covid-19 vaccines were the ones from Pfizer/BioNTech and Moderna. Both vaccines have very high « efficacy rates, » of around 95%. But the third vaccine introduced in the US, from Johnson & Johnson, has a considerably lower efficacy rate: just 66%.
Look at those numbers next to each other, and it’s natural to conclude that one of them is considerably worse. Why settle for 66% when you can have 95%? But that isn’t the right way to understand a vaccine’s efficacy rate, or even to understand what a vaccine does. And public health experts say that if you really want to know which vaccine is the best one, efficacy isn’t actually the most important number at all.