Vaccination offers long-lasting protection from the worst outcomes of COVID-19, according to a new study by the University of North Carolina at Chapel Hill.
The emergence of the delta and omicron variants has raised questions about whether breakthrough infections are caused by waning immunity or by the more transmissible variants.
Results of the study published in the New England Journal of Medicine suggest that declining immunity is responsible for breakthrough infections, but vaccines maintained protection from hospitalization and severe disease nine months after getting the first shot.
"The primary takeaway message from our study is that unvaccinated people should get vaccinated right away," said lead study author Danyu Lin, Ph.D., Dennis Gillings Distinguished Professor of Biostatistics at the UNC Gillings School of Global Public Health. "The results of our study also underscore the importance of booster shots, especially for older adults."
The study, which is a collaboration between the UNC-Chapel Hill and the North Carolina Department of Health and Human Services, examined data on COVID-19 vaccination history and health outcomes for 10.6 million North Carolina residents between December 2020 and September 2021.