Abstract Background Coronavirus disease 2019 (COVID-19) vaccine trials and post-implementation data suggest that vaccination decreases infections. We examine vaccination’s impact on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) case rates and viral diversity among health care workers (HCWs) during a high community prevalence period. Methods In this prospective cohort study, HCW received 2 doses of BNT162b2 or mRNA-1273. We included confirmed cases among HCWs from 9 December 2020 to 23 February 2021. Weekly SARS-CoV-2 rates per 100,000 person-days and by time from first injection (1–14 and ≥15 days) were compared with surrounding community rates. Viral genomes were sequenced. Results SARS-CoV-2 cases occurred in 1.4% (96/7109) of HCWs given at least a first dose and 0.3% (17/5913) of HCWs given both vaccine doses. Adjusted rate ratios (95% confidence intervals) were 0.73 (.53–1.00) 1–14 days and 0.18 (.10–.32) ≥15 days from first dose. HCW ≥15 days from initial dose compared to 1-14 days were more often older (46 vs 38 years, P = .007), Latinx (10% vs 8%, P = .03), and asymptomatic (48% vs 11%, P = .0002). SARS-CoV-2 rates among HCWs fell below the surrounding community, an 18% vs 11% weekly decrease, respectively ( P = .14). Comparison of 50 genomes from post–first dose cases did not indicate selection pressure toward known spike antibody escape mutations. Conclusions Our results indicate an early positive impact of vaccines on SARS-CoV-2 case rates. Post-vaccination isolates did not show unusual genetic diversity or selection for mutations of concern. Cases of SARS-CoV-2 among health care workers dropped rapidly with COVID-19 vaccination. Sequencing 50 breakthrough infections (overwhelmingly in 14 days after first dose) showed no clear sign of any differences in spike protein compared with time-matched, unvaccinated control sequences.
【저자키워드】 infection control, COVID-19 vaccine, Whole genome sequencing, viral evolution, SARS-CoV-2 infections, 【초록키워드】 COVID-19, SARS-CoV-2, Coronavirus disease 2019, Vaccine, coronavirus, vaccination, vaccine doses, Mutation, mRNA-1273, Genome, prospective cohort study, Spike protein, Prevalence, infections, Asymptomatic, HCWs, Community, Health care worker, selection pressure, genetic diversity, Breakthrough infection, dose, HCW, rate ratio, confirmed case, acute respiratory syndrome, Older, Confidence intervals, first dose, injection, positive, vaccine trial, Latinx, isolate, decrease, initial, Result, occurred, sequenced, Weekly, antibody escape mutations, dropped, of BNT162b2, with COVID-19, 【제목키워드】 coronavirus 2, Impact, Prospective, respiratory, strain, urban, sequence, worker, Rate,