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Comparative Effectiveness of the SARS-CoV-2 Vaccines During Delta Dominance

28 Pages Posted: 27 Jun 2022



Background: Several vaccines with demonstrated efficacy for coronavirus disease 2019 (Covid-19) are available. The vaccines’ differential effectiveness may have significant impacts, but information on comparative efficacy in large populations is limited. 

Methods: We used de-identified claims in a research database that included vaccination status and Covid-positivity status. Individuals > 18 years, fully vaccinated with Ad26.COV2.S /J&J/Janssen, mRNA-1273/Moderna, or BNT162b2/Pfizer-BioNTech by September 30, 2021, were included. Outcomes were SARS-CoV-2-infection, emergency department visits, outpatient visits, inpatient hospitalizations, intensive care unit (ICU) transfers, death, and hospice transfers through September 30, 2021. 

Results: Among ~6.5 million fully vaccinated individuals, mRNA-1273 performed better than BNT162b2 for infection, composite-hospitalization (hospitalization/ICU transfer/hospice transfer/death), and composite-ICU transfer (ICU transfer/hospice transfer/death) caused by B.1.612.7 (delta) variant infection. AD26.COV2.S performed worse than BNT162b2 for infection, composite-hospitalization, and composite-ICU transfers. The number needed to vaccinate (NNV) with mRNA1273 to prevent one hospitalization at 90 days was 3130 compared to AD26.COV2.S and 15,472 compared to BNT162b2. The NNV with mRNA1273 to prevent one ICU transfer at 90 days was 6358 compared to AD26.COV2.S and 34,279 compared to BNT162b2. For every one million individuals vaccinated with BNT162b compared to mRNA-1273, the approximate incremental inpatient cost would be $405,000 and the approximate incremental ICU cost would be $662,000. 

Conclusions: The two-dose mRNA vaccines’ effectiveness significantly exceeded the single-dose Ad26.COV2.S vaccine’s effectiveness from population health and cost-effectiveness perspectives. The mRNA1273 vaccine showed slightly more effectiveness than the BNT162b vaccine.

Funding: None to declare.

Declaration of Interest: We declare that we have no competing interests.

Ethical Approval: This research was determined to be exempt from human research regulations by the UnitedHealth Group Office of Human Research Affairs.

Keywords: Key Words: Covid-19, vaccine, delta variant, comparative efficacy, cost-effectiveness

Suggested Citation

Islam, Nazmul and Griffin, Daniel and Jarvis, Megan S. and Cohen, Kenneth R., Comparative Effectiveness of the SARS-CoV-2 Vaccines During Delta Dominance. Available at SSRN: or

Nazmul Islam

Optum Labs ( email )

Daniel Griffin

Optum Labs

Megan S. Jarvis

Optum Labs ( email )

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