How does prior infection and vaccination relate to the risk of incident SARS-CoV-2 infection/reinfection? A prospective cohort study among nine clinical sites in the USA, February 2021 to January 2023
3 days ago
- #Vaccination Effectiveness
- #COVID-19
- #Prior Infection
- Study examined effectiveness of vaccination doses (0, 1, 2, ≥3) and prior infection on SARS-CoV-2 infection/reinfection risk.
- Effectiveness generally increased with more vaccine doses and prior infection, with strongest protection from ≥3 doses plus prior infection.
- Prior infection provided additional protection, especially for those with 0 or 1 vaccine doses.
- Protection from vaccination, prior infection, or both decreased markedly during the Omicron period compared to pre-Omicron.
- Re-classifying prior infection based on antibody levels had minimal effect on the study's conclusions.