ABSTRACT
BACKGROUND: The immunogenicity of different COVID-19 vaccine regimens and combinations in naïve and convalescent individuals has not been formally tested in controlled studies, and real-life observational studies are scarce. METHODS: We assessed the SARS-CoV-2 infection and COVID-19 vaccination-induced immunity of 697 hospital workers at the University Medical Center Hamburg-Eppendorf between 17 and 31 January 2022. RESULTS: The overall prevalence of anti-NC-SARS-CoV-2 antibodies indicating prior infection was 9.8% (n = 68) and thus lower than the seroprevalence in the general population. All vaccinated individuals had detectable anti-S1-RBD-SARS-CoV-2 antibodies (median AU/mL [IQR]: 13,891 [8505-23,543]), indicating strong protection against severe COVID-19. Individuals who received three COVID-19 vaccine doses (median AU/mL [IQR]: 13,856 [8635-22,705]) and those who resolved a prior SARS-CoV-2 infection and had received two COVID-19 vaccine doses (median AU/mL [IQR] 13,409 [6934-25,000]) exhibited the strongest humoral immune responses. CONCLUSIONS: The current study indicates that three exposures to the viral spike protein by either SARS-CoV-2 infection or COVID-19 vaccination are necessary to elicit particularly strong humoral immune responses, which supports current vaccination recommendations.
ABSTRACT
We sequentially assessed the presence of SARS-CoV-2 IgG antibodies in 1253 hospital workers including 1026 HCWs at the University Medical Center Hamburg-Eppendorf at three time points during the early phase of the epidemic. By the end of the study in July 2020, the overall seroprevalence was 1.8% (n = 22), indicating the overall effectiveness of infection control interventions in mitigating coronavirus disease 2019 (COVID-19) in hospital workers.