Reference:
Shrestha, N. K., Burke, P. C., Nowacki, A. S., Simon, J. F., Hagen, A., & Gordon, S. M. (2022). Effectiveness of the Coronavirus Disease 2019 (COVID-19) Bivalent Vaccine. medRxiv. https://doi.org/10.1101/2022.12.17.22283625
Summary:
This study evaluated the effectiveness of the bivalent COVID-19 vaccine among 51,011 employees at the Cleveland Clinic. The results indicated a 30% effectiveness in preventing COVID-19 infection during a period when the vaccine strains were those circulating in the community. The research revealed that 41% of participants had a prior COVID-19 infection, and 83% had received at least two vaccine doses. COVID-19 cases were recorded in 5% of participants during the study. Analysis showed that the vaccine provided modest protection, with a hazard ratio of 0.70, indicating a 30% reduction in the risk of infection. The study highlighted that the risk of COVID-19 increased with time since the last infection and the number of vaccine doses received. Overall, while the bivalent vaccine offered some protection, its effectiveness raised questions about the long-term impact of multiple vaccine doses.