Evidence for increased breakthrough rates of SARS-CoV-2 variants of concern in BNT162b2 mRNA vaccinated individuals

The BNT162b2 mRNA vaccine is highly effective against SARS-CoV-2. However,apprehension exists that variants of concerns (VOCs) may surmount vaccine protection,following evidence showing reduced neutralization of VOCs B.1.1.7 and B.1.351 inlaboratory assays. We performed a matched cohort study to examine the distribution ofVOCs in infections of vaccinees, and hypothesized that if vaccine effectiveness against a VOCis reduced, its proportion among breakthrough cases would be higher than in unvaccinatedcontrols. We showed that vaccinees who tested positive at least a week after the seconddose, were disproportionally infected with B.1.351, compared with controls. Those whotested positive between two weeks after the first dose and a week after the second dose,were disproportionally infected by B.1.1.7, suggesting reduced vaccine effectiveness againstboth VOCs at particular time windows. Our results emphasize the importance of rigorouslytracking viral variants, and of increasing vaccination to prevent the spread of VOCs.