Selection Effects and COVID-19 Mortality Risk after Pfizer vs. Moderna Vaccination: Evidence from Linked Mortality and Vaccination Records

14 Pages Posted: 20 Jan 2023 Last revised: 22 May 2023

See all articles by Vladimir A. Atanasov

Vladimir A. Atanasov

William and Mary - Raymond A. Mason School of Business

Paula Natalia Barreto Parra

Northwestern University

Jeff Whittle

Clement J. Zablocki Medical Center - Department of Medicine

John Meurer

Medical College of Wisconsin

Benjamin Weston

Medical College of Wisconsin

Qian (Eric) Luo

Fitzhugh Mullan Institute for Health Workforce Equity, The George Washington University

Andy Yuan

Northwestern University - Pritzker School of Law

Lorenzo Franchi

Northwestern University - Pritzker School of Law

Ruohao Zhang

Pennsylvania State University

Bernard S. Black

Northwestern University - Pritzker School of Law

Date Written: January 10, 2023

Abstract

The Pfizer and Moderna COVID-19 vaccines have often been described as providing similar protection against mortality. However, most comparisons do not take into account the potential selection effects for who gets vaccinated, with how many doses, when, and with which vaccine. We report evidence on large selection effects and use a novel method to control for these effects. Instead of studying COVID-19 mortality, we study the COVID-19 Excess Mortality Percentage (CEMP), defined as COVID-19 deaths divided by non-COVID natural deaths for the same population. The CEMP measure uses non-COVID-19 natural deaths as a proxy for population health and thus controls, albeit imperfectly, for selection effects. We study adults vaccinated with the Pfizer-BioNTech (BNT162b2) and Moderna (mRNA1273) vaccines, and report mortality risk (RMR) for each vaccine relative to the unvaccinated and to the other vaccine, using linked mortality and vaccination records for Milwaukee County, Wisconsin, through June 30, 2022. The vaccines provided similar protection for persons aged 18-59, but for persons aged 60+, RMRs for two-dose Pfizer vaccinees were over twice those for Moderna vaccinees. Pfizer two-dose RMR for ages 60+ over April 2021-June 2022 was 248% of Moderna [95% CI=175%,353%]; in the Omicron period, Pfizer RMR was 57% versus 23% for Moderna. Both vaccines demonstrated waning two-dose effectiveness over time, especially for ages 60+. For booster recipients, the Pfizer-Moderna gap narrowed and became statistically insignificant. Younger persons (aged 18-59) were well-protected against death by two doses of either vaccine and highly protected by three doses (no deaths in our sample among over 100,000 vaccinees). These results support booster importance for ages 60+, especially for Pfizer recipients.

The Online Appendix for this paper is available at http://ssrn.com/abstract=4321773

Note:
Funding Information: This project was funded by the National Institutes of Health, award 3 UL1 TR001436-06S1.

Declaration of Interests: The authors have no competing interests.

Ethics Approval Statement: Approved by the Medical College of Wisconsin Human Research Review Board.

Keywords: COVID-19 mortality rates; COVID-19 Excess Mortality Percentage; vaccine effectiveness, Moderna vaccine, mRNA1273, Pfizer vaccine, Pfizer-BioNTech vaccine, BNT162b2.

Suggested Citation

Atanasov, Vladimir A. and Barreto Parra, Paula Natalia and Whittle, Jeffrey and Meurer, John and Weston, Benjamin and Luo, Qian and Yuan, Andy and Franchi, Lorenzo and Zhang, Ruohao and Black, Bernard S., Selection Effects and COVID-19 Mortality Risk after Pfizer vs. Moderna Vaccination: Evidence from Linked Mortality and Vaccination Records (January 10, 2023). Vaccines 2023, 11(5), 971, Northwestern Law & Econ Research Paper No. 22-17, Available at SSRN: https://ssrn.com/abstract=4321768 or http://dx.doi.org/10.2139/ssrn.4321768

Vladimir A. Atanasov

William and Mary - Raymond A. Mason School of Business ( email )

P.O. Box 8795
Williamsburg, VA 23187-8795
United States

Paula Natalia Barreto Parra

Northwestern University ( email )

2001 Sheridan Road
Evanston, IL 60208
United States

Jeffrey Whittle

Clement J. Zablocki Medical Center - Department of Medicine ( email )

5000 W. National Ave.
Milwaukee, WI 53295
United States

HOME PAGE: http://www.mcw.edu/display/router.asp?DocID=10377

John Meurer

Medical College of Wisconsin ( email )

United States
4145100375 (Phone)

HOME PAGE: http://https://www.mcw.edu/departments/institute-for-health-and-equity/people/john-meurer-md-mba

Benjamin Weston

Medical College of Wisconsin

Qian Luo

Fitzhugh Mullan Institute for Health Workforce Equity, The George Washington University ( email )

2175 K St NW
Washington, DC 20052
United States

Andy Yuan (Contact Author)

Northwestern University - Pritzker School of Law ( email )

375 E. Chicago Ave
Chicago, IL 60611
United States

Lorenzo Franchi

Northwestern University - Pritzker School of Law ( email )

2001 Sheridan Road
Evanston, IL 60208
United States

Ruohao Zhang

Pennsylvania State University ( email )

University Park, PA 16802-3306
United States

Bernard S. Black

Northwestern University - Pritzker School of Law ( email )

375 E. Chicago Ave
Chicago, IL 60611
United States
312-503-2784 (Phone)

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