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CDC Evaluates Effectiveness of Three COVID-19 Vaccines

MedicalResearch.com Interview with:
Scott Pauley

Press Officer, News Media Branch
Division of Public Affairs
Office of the Associate Director for Communication

MedicalResearch.com: What is the background for this study?

  • In this real-world study of vaccine effectiveness:
    • Researchers compared hospitalized patients who tested positive for the virus that causes COVID-19 (case patients) to hospitalized patients who tested negative for the virus (control patients)
    • Vaccine effectiveness was calculated for each type of vaccine by comparing the proportion of cases patients and control patients vaccinated
    • 3,689 patients were included (1,682 case-patients and 2,007 control-patients)

Vaccination status breakdown: 2,362 unvaccinated; 476 fully vaccinated with Moderna; 738 fully vaccinated with Pfizer-BioNTech; and 113 fully vaccinated with Janssen vaccine.

MedicalResearch.com: What are the main findings?

Response: A study looking at the effectiveness of COVID-19 vaccines showed that all three COVID-19 vaccines authorized or approved for use in the United States provided strong protection against COVID-19 hospitalization.

Full vaccination was 93% effective against hospitalization for the Moderna vaccine, 88% effective for the Pfizer-BioNTech vaccine, and 71% effective for Johnson & Johnson’s Janssen vaccine.

MedicalResearch.com: What should readers take away from your report?

Response: Readers should understand the critical need to get vaccinated. Vaccination helps prevent spread of the virus that causes COVID-19 by helping the body produce antibodies to fight the virus. Preventing spread helps stop severe illness and death from COVID-19.  While Moderna was the most effective vaccine, people should take any vaccine available to them. All three vaccines offer protection against severe COVID-19. 

MedicalResearch.com: What recommendations do you have for future research as a result of this work?

Response: We’ll need to continue to monitor vaccine effectiveness over time to see if the vaccines need to change, or if additional doses will be needed. Research can also show how long or if protection lasts as new variants emerge.

MedicalResearch.com: Is there anything else you would like to add?

Response: Please get vaccinated if you have not done so. All disclosures are included in the MMWR.


Self WH, Tenforde MW, Rhoads JP, et al. Comparative Effectiveness of Moderna, Pfizer-BioNTech, and Janssen (Johnson & Johnson) Vaccines in Preventing COVID-19 Hospitalizations Among Adults Without Immunocompromising Conditions — United States, March–August 2021. MMWR Morb Mortal Wkly Rep. ePub: 17 September 2021. DOI: http://dx.doi.org/10.15585/mmwr.mm7038e1



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Last Updated on September 17, 2021 by Marie Benz MD FAAD