Real-world data from Qatar suggests 2 doses of Pfizer’s vaccine are needed against variants

Real-world data from Qatar suggests 2 doses of Pfizer’s vaccine are needed against variants

A second dose of Pfizer's two dose COVID-19 vaccine boosted protection against coronavirus variants including the worrisome variant from South Africa, real-world data from Qatar suggests.

The Qatari study, published as a letter in the New England Journal of Medicine on Wednesday, found that the COVID-19 vaccine co-developed by Pfizer and BioNTech, was 54% effective against severe illness after one dose and more than 90% effective against severe COVID-19 two weeks after the second dose. Qatar has been giving the shots at 21 days intervals. 

The study authors found that a second dose of Pfizer's vaccine provided strong protection against variants, including against B.1.351, the variant first found in South Africa. Pfizer's previous lab experiments have found that antibody's produced by the vaccine didn't work so well against a pseudovirus similar to B.1.351. It wasn't clear how this lab finding would translate into the real-world.

In the Qatari study, Pfizer's vaccine was 75% effective at preventing infection of varying severity caused by the variant first found in South Africa, called B.1.351, after two doses, and 16.9% effective against B.1.351 infections after one dose.

The study also adds to a growing body of real-world evidence, including from Israel, that suggests Pfizer's vaccine is highly effective