Effectiveness of mRNA-BNT162b2, mRNA-1273, and ChAdOx1 nCoV-19 vaccines against COVID-19 in health care workers: an observational study using surveillance data

Paris, Christophe; Perrin, Sophie; Hamonic, Stephanie; Bourget, Baptiste; Roué, Clémence; Brassard, Olivier; Tadié, Emilie; Gicquel, Vincent; Bénézit, François; Thibault, Vincent; Garlantézec, Ronan; Tattevin, Pierre

OBJECTIVES: Health care workers (HCWs), at increased risk of COVID-19, were among the primary targets for vaccine campaigns. We aimed to estimate the effectiveness of the 3 first COVID-19 vaccines available in Western Europe for their protection. METHODS: We merged two prospective databases that systematically recorded, in our institution: i) HCWs positive for SARS-CoV-2 by RT-PCR on nasopharyngeal sample; ii) HCWs who received at least one dose of COVID-19 vaccine. We excluded HCWs with SARS-CoV-2 infection during the 6 months prior to the study. HCWs were categorized as non-vaccinated if they received no vaccine and until first injection +13 days, partially vaccinated from first injection +14 days to second injection +13 days, and fully vaccinated thereafter. RESULTS: Of the 8,165 HCWs employed in our institution, 360 (4.4%) tested positive for SARS-CoV-2 by RT-PCR during the study period (January 4(th) to May 17(th) 2021): Incidence was 9.1% (8.2-10.0) in non-vaccinated HCWs; 1.2% (0.7-1.9) after one dose of ChAdOx1 nCoV-19; 1.4% (0.6-2.3), and 0.5% (0.1-1.0), after one, and two doses, of mRNA BNT162b2; 0.7% (0.1-1.9), and 0%, after one, and two doses, of mRNA-1273 (P<0.0001). Vaccine effectiveness (Cox Model), was estimated at, respectively, 86.2% (76.5-91.0), 38.2% (6.3-59.2), and 49.2% (19.1-68.1) 14 days after the first dose for ChAdOx1 nCoV-19, mRNA-1273, and mRNA-BNT162b2; 100% (ND), and 94.6% (61.0-99.2) 14 days after the second dose for mRNA-1273, and mRNA-BNT162b2. CONCLUSIONS: In this real-world study, the observed effectiveness of COVID-19 vaccines in HCWs was in line with the efficacy reported in pivotal randomized trials.