Single COVID dose may leave virus-naïve vaccinees vulnerable to variantsThe first dose of a two-dose COVID-19 vaccine regimen confers a robust immune response against the B117 and B1351 variants in people previously infected with the coronavirus—but not in those in those never infected, according to a new study led by researchers from Imperial College London, Queen Mary University of London, and University College London.The study, published late last week in Science, involved analyzing blood samples from UK healthcare workers at two hospitals after receiving their first dose of the Pfizer/BioNTech vaccine in December 2020.Among 23 participants who previously had mild or asymptomatic COVID-19 roughly 40 weeks before, 22 (96%) had T cell