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BNT162b2 Vaccine Effectiveness in Preventing Asymptomatic Infection with SARS-CoV-2 Virus: A Nationwide Historical Cohort Study

14 Pages Posted: 3 Mar 2021

See all articles by Anthony David Heymann

Anthony David Heymann

Meuhedet Health Maintenance Organization

Galia Zacay

Meuhedet Health Maintenance Organization

David Shasha

Meuhedet Health Maintenance Organization

Ronen Bareket

Meuhedet Health Maintenance Organization

Itai Kadim

Meuhedet Health Maintenance Organization

Fabienne Hershkowitz Sikron

Meuhedet Health Maintenance Organization

Judith Tsamir

Meuhedet Health Maintenance Organization

David Mossinson

Meuhedet Health Maintenance Organization

More...

Abstract

Background: There is strong evidence regarding the efficacy and effectiveness of BNT162b2 vaccine in preventing symptomatic infection with SARS-CoV-2 virus. There is a paucity of data regarding effectiveness in prevention of asymptomatic infection.

Methods: In this real-world study, we identified a sub-population of patients in a large health maintenance organisation who were repeatedly tested for SARS-CoV-2 infection using a PCR test. We used these patients as the cohort for the study, and compared individuals who were vaccinated with BNT162b2 mRNA vaccine to the unvaccinated ones. A positive SARS-CoV-2 PCR test result was used as the outcome. Follow-up period was from Jan 1,2021 until Feb 11, 2021.

Findings: 6,286 individuals were included in the cohort. Seven days following the second vaccine dose, a rate of six positive PCR tests per 10,000 patient-days was recorded, compared with a rate of 53 positive tests per 10,000 patient-days for the unvaccinated group. The estimated vaccine effectiveness against infection with SARS-CoV-2 virus after two vaccine doses was 89% (confidence interval 82%-94%). The estimated effectiveness two weeks following the first vaccine dose was 61% (confidence interval 49%-71%).

Interpretation: In this study, vaccination with BNT162b2 reduced infection rates among individuals who underwent screening by frequent SARS-CoV-2 PCR testing. Using a cohort of frequently tested individuals reduced the indication bias for the PCR testing, which enabled estimation of asymptomatic infection rates.

Funding: This study received no funding.

Declaration of Interests: DS reports receiving personal fees from Pfizer, outside the submitted work (advisory board on Trumenba); and Consultation fees from GSK and Gilead. The other authors declare no competing interests.

Ethics Approval Statement: This study was approved by MHMO’s institutional review board number 03-17-02- 21, and investigators were exempt from requesting informed consent.

Suggested Citation

Heymann, Anthony David and Zacay, Galia and Shasha, David and Bareket, Ronen and Kadim, Itai and Sikron, Fabienne Hershkowitz and Tsamir, Judith and Mossinson, David, BNT162b2 Vaccine Effectiveness in Preventing Asymptomatic Infection with SARS-CoV-2 Virus: A Nationwide Historical Cohort Study. Available at SSRN: https://ssrn.com/abstract=3796868 or http://dx.doi.org/10.2139/ssrn.3796868

Anthony David Heymann (Contact Author)

Meuhedet Health Maintenance Organization ( email )

Israel

Galia Zacay

Meuhedet Health Maintenance Organization ( email )

Israel

David Shasha

Meuhedet Health Maintenance Organization ( email )

Israel

Ronen Bareket

Meuhedet Health Maintenance Organization ( email )

Israel

Itai Kadim

Meuhedet Health Maintenance Organization ( email )

Israel

Fabienne Hershkowitz Sikron

Meuhedet Health Maintenance Organization ( email )

Israel

Judith Tsamir

Meuhedet Health Maintenance Organization ( email )

Israel

David Mossinson

Meuhedet Health Maintenance Organization ( email )

Israel

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