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 hospitalizations by COVID-19 vaccination status and previous COVID-19 diagnosis — California and New York, May–November 2021. Morbidity and Mortality Weekly Report, 71, 1-12. https://doi.org/10.15585/mmwr.mm7104e1
Summary:
This report examines the impact of COVID-19 vaccination and prior infection on case and hospitalisation rates in California and New York between May and November 2021. By analysing data from these states, which account for 18% of the U.S. population, the study reveals that unvaccinated individuals without prior infection had the highest COVID-19 incidence and hospitalisation rates. Vaccination significantly reduced infection rates, with vaccinated individuals showing lower case rates compared to unvaccinated peers. Notably, the emergence of the Delta variant altered these dynamics, leading to increased case rates among vaccinated persons over time. Vaccination remains essential in preventing severe outcomes, and the findings highlight the importance of booster doses as immunity wanes and new variants emerge.