Veterans Study Compares Pfizer with Moderna Vaccines Interview with:

Dr. Barbra Dickerman, PhD CAUSALab investigator and instructor Department of Epidemiology Harvard T.H. Chan School of Public Health

Dr. Dickerman

Dr. Barbra Dickerman, PhD
CAUSALab investigator and instructor
Department of Epidemiology
Harvard T.H. Chan School of Public Health What is the background for this study?

Response: Early randomized trials showed that the BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna) vaccines were both remarkably effective at preventing symptomatic disease, when comparing each vaccine with no vaccine. However, head-to-head comparisons of these vaccines have been lacking, leaving open the question of which vaccine is more effective. 

In this study, we analyzed the VA’s high-quality databases in a way that emulated the design of the hypothetical trial that would have answered this question. Specifically, we used the findings from the original trials to benchmark our methods and then extended them to provide novel evidence for the comparative effectiveness of these two vaccines in a real-world setting and across diverse subgroups and different time periods. What are the main findings?

Response: First, these results confirm that both the Moderna and Pfizer vaccines are highly effective, with low risks of breakthrough Covid-19 outcomes regardless of the vaccine received.

The large sample size in this study allowed us to detect subtle differences between these two highly effective vaccines. Specifically, we found evidence for a slightly lower risk of Covid-19 outcomes for the Moderna vaccine compared with the Pfizer vaccine. This pattern was consistent across diverse subgroups and across periods marked by alpha or delta variant predominance. What do the results imply for booster shots?

Response This study was not designed to compare how well the vaccines work after an additional booster dose. What recommendations do you have for future research as a result of this work?

Response: We are currently extending our methodology to quantify the comparative safety of these vaccines. Is there anything else you would like to add?

Implications for individuals choosing between vaccines:

Given the high effectiveness of both vaccines, either one is strongly recommended to any individual offered the choice between the two.

Implications for those recommending vaccines:

While the identified differences in estimated risk between the two vaccine groups were small on the absolute scale, they may be meaningful when considering the large population scale at which these vaccines are deployed. This information may be helpful to larger decision-making bodies. However, any choice between vaccines must also consider their comparative safety, which was not studied here. This is something that we are actively investigating.

I have no disclosures. 


Comparative Effectiveness of BNT162b2 and mRNA-1273 Vaccines in U.S. Veterans

Barbra A. Dickerman, Ph.D., Hanna Gerlovin, Ph.D., Arin L. Madenci, M.D., Ph.D.,
Katherine E. Kurgansky, M.P.H., Brian R. Ferolito, M.Sc., Michael J. Figueroa Muñiz, B.Sc., David R. Gagnon, M.D., Ph.D., M.P.H., J. Michael Gaziano, M.D., M.P.H., Kelly Cho, Ph.D., Juan P. Casas, M.D., Ph.D., and Miguel A. Hernán, M.D., Dr.P.H.
NEJM: December 1, 2021
DOI: 10.1056/NEJMoa2115463



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