That Pfizer Shot

Posted by Matt Birchler
— 1 min read

I got the Pfizer vaccine and there is new data out today on how it's holding up so far:

Overall, the vaccine was 91 percent effective against symptomatic COVID-19 over six months. It was the most protective in the stretch starting seven days after the second dose and running for two months: in that window, it was 96 percent effective. Its efficacy then dropped around 6 percent every two months — to 90 percent between months two and four after vaccination, and to around 84 percent between months four and six after vaccination.


There wasn’t a similar drop in efficacy against severe cases of COVID-19 — defined as cases where blood oxygen levels drop below 93 percent and heart and respiratory rate are elevated. The vaccine’s efficacy against those severe cases stayed high at 97 percent for the entire six-month stretch after people got their shots.

So basically, protection against symptomatic COVID-19 dropped a bit, although the odds of you getting a severe case hardly dropped at all.

As I'm writing this, we're about to cross 4 billion doses of these vaccines (Pfizer and otherwise) delivered worldwide, and I don't know if there has every been vaccines with this much data around them.