Catherine H. Bozio, PhD MPH Epidemiologist Centers for Disease Control and Prevention

COVID-19: CDC Finds Vaccination Provides Better Protection Than Prior Infection Interview with:

Catherine H. Bozio, PhD MPH Epidemiologist Centers for Disease Control and Prevention

Dr. Bozio

Catherine H. Bozio, PhD MPH
Centers for Disease Control and Prevention What is the background for this study?

Response: We wanted to understand what protection previous infection with
SARS-CoV-2 (the virus that causes COVID-19) and COVID-19 vaccination can provide. What are the main findings? Is the finding true of all the available vaccines?  With/without booster shots?

Response: Among people who were hospitalized with COVID-like illness, CDC found that those who were unvaccinated and had a recent infection were 5 times more likely to have COVID-19 than those who were recently fully vaccinated and did not have a prior infection.  The study looked at more than 7,000 people who were hospitalized in 187 hospitals across 9 states between January and September 2021.

This analysis included fully vaccinated adults who received 2 doses of either mRNA COVID-19 vaccine.  This analysis did not include the Janssen vaccine, and the report’s findings should not be generalizable to the Janssen vaccine.  This analysis did not evaluate the receipt of COVID-19 booster doses. What should readers take away from your report?

Response: The data demonstrate that vaccination can provide a higher, more robust, and more consistent level of immunity to protect people from hospitalization for COVID-19 than infection alone for at least 6 months.  CDC recommends all eligible people should be vaccinated against COVID-19 as soon as possible, including unvaccinated people previously infected with COVID-19. What recommendations do you have for future research as a result of this work?

Response: This study focused on the recent protection from infection-induced and vaccine-induced immunity among adults hospitalized with symptoms similar to COVID-19, though it is possible that estimates could be affected by time.  Understanding infection-induced and vaccine-induced immunity over time is important, particularly for future studies to consider. Is there anything else you would like to add?

Response: These findings are among adults hospitalized with symptoms similar to COVID-19, and the main analysis focused on recent protection from either prior SARS-CoV-2 infection or from full vaccination of an mRNA COVID-19 vaccine (specifically, 3-6 months since prior infection or vaccination). I have nothing to disclosure.


Bozio CH, Grannis SJ, Naleway AL, et al. Laboratory-Confirmed COVID-19 Among Adults Hospitalized with COVID-19–Like Illness with Infection-Induced or mRNA Vaccine-Induced SARS-CoV-2 Immunity — Nine States, January–September 2021. MMWR Morb Mortal Wkly Rep. ePub: 29 October 2021. DOI: icon. 



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Last Updated on November 2, 2021 by Marie Benz MD FAAD