January 20, 2022 – A new study published by the Centers for Disease Control and Prevention finds that both the vaccination and a prior COVID infection helped to protect against the Delta variant. Researchers analyzed the risk of COVID-19 infection and hospitalization among four groups: vaccinated with prior infection, vaccinated without prior infection, unvaccinated with prior infection, and unvaccinated without prior infection.
The study found that as the Delta variant became predominant in the US, people who survived a previous COVID-19 infection had lower case rate than those who were vaccinated alone. Additionally, hospitalization was much higher for the group that was unvaccinated with no prior infection.
Dr. Benjamin Silk, lead for CDC’ surveillance and analytics on the Epi-Task Force, said, “Experts first looked at previous infections confirmed with laboratory test by the spring of 2021, when the Alpha variant was predominant across the country. Before the Delta variant, Covid-19 vaccination resulted in better protection against a subsequent infection than surviving a previous infection. When looking at the summer and the fall of 2021, when Delta became the dominant in this country, however, surviving a previous infection now provided greater protection against subsequent infection than vaccination.”
Even with the level of protection provided by a previous infection, health experts are making it clear that vaccinations provide the safest level of protection against COVID-19. Dr. Erica Pan, state epidemiologist for the California Department of Public Health, said, “The data clearly shows that vaccination provides the safest protection against COVID-19 and additional protection for individuals who have had a prior infection. In addition, it shows that people who remain unvaccinated are at the greatest risk of hospitalization and death. Outside of this study, recent data on the highly contagious Omicron variant shows that getting a booster provides significant additional protection against infection, hospitalization and death.”