Duration of protection from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) after primary homologous vaccination or first infection.

Publication date: Jul 04, 2025

The aim of this study was to determine the duration of protection in 95 % of the population after primary vaccination (PV) and/or acquiring SARS-CoV-2 infection in order to make public health decisions. A study was a retrospective cohort study conducted in Osijek-Baranja County, Croatia, between December 27, 2020, and May 12, 2023. A total of 119,596 subjects of both sexes and all age groups were analyzed. The method of survival analysis was used. The length of protection (LoP) for 95 % and 90 % of the population with first infection was 256 (confidence interval (CI) 251-264) days and 365 (CI 350-381) days, respectively. In those primarily vaccinated, the longest duration of protection was recorded in subjects having received primary homologous vaccination with Spikevax (Moderna), 143 (CI 133-150) and 192 (CI 183-201) days, followed by those with Comirnaty (BioNTech/Pfizer), 119 (CI 116-122) and 168 (CI 165-170) days, respectively. The respective duration of protection was 77 (71-84) and 164 (154-172) days for Jcovden (Janssen-Cilag), and 125 (118-131) and 149 (144-154) days for Vaxzevria (AstraZeneca). Protection after SARS-CoV-2 infection was longest as compared with the LoP following primary vaccination with any of the vaccines. The interval for vaccination of the general population previously infected with SARS-CoV-2 is on average twice the protection provided by primary vaccination with any homologous vaccine. Conclusions based on the study results are relevant for making public health measures concerning re-vaccination timing.

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