At a time when the answer is more urgent than ever – especially as the British government has decided to delay the second dose of all currently approved Covid-19 vaccines from 3-4 weeks to 12, and Russia is trialling a single-dose regimen of its Sputnik V vaccine named “Sputnik-Light” – it’s also surprisingly complicated. Here’s what we know so far.
According to Pfizer data published in December 2020, the Pfizer-BioNTech vaccine is roughly 52% effective after the first dose.
As the chief executive of Pfizer, Albert Bourla, explained in December that it would be a “big mistake” to skip the second dose, because it almost doubles the amount of protection you get.
Pfizer and BioNTech themselves have already urged caution on the grounds that their data ends at day 21… It’s possible that the protection people seem to have will suddenly drop off after that point – in fact, this wouldn’t be surprising based on the way the immune system usually works.