%0 Journal Article
%T Postvaccination infections among staff of a tertiary care hospital after vaccination with severe acute respiratory syndrome coronavirus 2 vector and mRNA-based vaccines.
%A Brunner-Ziegler S
%A Spath T
%A Kornek G
%A König F
%A Parschalk B
%A Schnetzinger M
%A Straßl RP
%A Savic R
%A Foit A
%A Resch H
%A Thalhammer F
%J Clin Microbiol Infect
%V 28
%N 4
%D Apr 2022
%M 34915073
%F 13.31
%R 10.1016/j.cmi.2021.11.023
%X <B>OBJECTIVE: </B>The identification of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen or RNA in respiratory specimens ≥14 days after administration of all recommended doses of authorized coronavirus disease 2019 (COVID-19) vaccines is defined as breakthrough infection. In the present investigation, mRNA and vector-based SARS-CoV-2 vaccines were analysed with respect to postvaccination infections in vaccinated hospital employees.<BR><B>METHODS: </B>A total of 8553 staff members were vaccinated with BNT162b2 (47%) or ChAdOx1-S (53%) between January and May 2021. In a retrospective observational cohort study, incidence of SARS-CoV-2 postvaccination infections was analysed in relation to demographic data, viral load, virus variants, vaccine brand and vaccination status at time of positive PCR test (fully vaccinated: ≥14 days since second dose; partially vaccinated: >21 days since first, but <14 days after second dose; insufficiently vaccinated: <22 days since first dose).<BR><B>RESULTS: </B>Within the follow-up period, ending on 31 July 2021, person-time at risk-adjusted monthly rates for SARS-CoV-2 postvaccination infections were 0.18% (BNT162b2) and 0.57% (ChAdOx1-S) for insufficiently vaccinated, 0.34% (BNT162b2) and 0.32% (ChAdOx1-S) for partially vaccinated and 0.06% (BNT162b2) and 0.04% (ChAdOx1-S) for fully vaccinated participants. The two vaccine types did not differ with respect to hazard ratios for any of the respective postvaccination infection types. No cases of COVID-19-related hospitalizations or deaths were reported. Genotyping of positive PCR specimens revealed 42 variants of concern: B.1.1.7 (Alpha variant; n = 34); B.1.351 (Beta variant; n = 2), B.1.617.2 (Delta variant; n = 6).<BR><B>CONCLUSIONS: </B>BNT162b2 and ChAdOx1-S are both effective in preventing breakthrough infections; however, it seems important, that all recommended vaccine doses are administered.