Reference:
León, T. M., Dorabawila, V., Nelson, L., Lutterloh, E., Bauer, U. E., Backenson, B., Bassett, M. T., Henry, H., Bregman, B., Midgley, C. M., Myers, J. F., Plumb, I. D., Reese, H. E., Zhao, R., Briggs-Hagen, M., Hoefer, D., Watt, J. P., Silk, B. J., Jain, S., & Rosenberg, E. S. (2022). COVID-19 cases and hospitalisations by COVID-19 vaccination status and previous COVID-19 diagnosis — California and New York, May–November 2021. Morbidity and Mortality Weekly Report, 71(4), 125-132. https://doi.org/10.15585/mmwr.mm7104a4
Summary:
This study examined COVID-19 cases and hospitalisation rates among different cohorts in California and New York from May to November 2021. It revealed that unvaccinated individuals without prior COVID-19 diagnoses had the highest infection rates. Vaccination significantly reduced the risk of infection and hospitalisation across all groups. Notably, those with prior infections also showed strong protection against reinfection. As the Delta variant became prevalent, infection rates increased among vaccinated individuals, although they remained lower than among unvaccinated individuals. The findings underscore the critical role of vaccination in preventing severe COVID-19 outcomes, even as new variants emerge.