Pfizer COVID vaccine shows varied effect against variants, study suggestsOne dose of the Pfizer/BioNTech COVID-19 vaccine appears to be not very protective against the B117 variant, and two doses may not be as effective against the B1351 variant, according to a non–peer-reviewed, real-world Israeli study posted late last week on the medRxiv preprint server.Led by researchers at Tel Aviv University, the case-control study compared nearly 400 people who had received one or two doses of the Pfizer vaccine and were infected by SARS-CoV-2 with matched unvaccinated, infected controls.Vaccinated participants were infected either at least 1 week after their second dose or between at least 2 weeks after the first dose and before 1 week after the