Thread by @profshanecrotty

Big knowledge gap was will the COVID RNA vaccines work vs B.1.351 and P.1 variants. Now Pfizer protects well vs B.1.351!
🔵 ~75% against infection
🔵 ~97% against severe/fatal disease

Very good news for the rest of 2021 for any countries using Pfizer and Moderna vaccines! 🧵

B.1.351 and P.1 (1st found in South Africa and Brazil) have been the two biggest variants of concern that have a degree of antibody escape. As of this morning (and February), some vaccines (AZ) showed only 11% effectiveness against B.1.351 cases,

and the best clinical trial data was ~50-66% vaccine efficacy against B.1.351 cases (J&J and Novavax), and only data for non-hospitalized cases (because of the size of the studies). Leaving lots of uncertainty.

Now today we have this: !
Real world vaccine data from many thousands of COVID-19 cases.
nejm.org/doi/full/10.10…

LARGE new dataset from Qatar showing very clear vaccine efficacy against variants.
🔵 ~75% vs documented infection
🔵 ~97% vs severe to fatal disease

(Over 20,000 COVID-19 cases, and 468 severe to fatal cases to compare [using WHO definition, severe = hospitalized + O])

Such good news!

Given what we have seen with other real world COVID vaccine data, it is likely that with these efficacy %s the Pfizer-BioNtech COVID vaccine also helps prevent transmission of B.1.351, which is good, but there is no direct data on that topic.

P.1 variant is not identical to B.1.351, but it is reasonable to bet that the efficacy against P.1 is likely to be in a similar range, because of their observed virological and immunological similarities to date.

Pfizer vaccine efficacy against B117 (1st seen in the UK) in this new Qatar study was ~90%. That is comparable to what was reported previously from the UK and Israel. Not surprising at all. Still good news.🙂

Is the variant protection all antibodies, or antibodies plus T cells, or mostly T cells? Undetermined.

It is likely that these Pfizer vaccine protection results will be similar in the future for the Moderna vaccine.

Overall, definitely great news!