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Decreased Infectivity Following BNT162b2 Vaccination

28 Pages Posted: 7 Apr 2021

See all articles by Gili Regev-Yochay

Gili Regev-Yochay

Tel-Aviv University - Sackler Faculty of Medicine

Sharon Amit

Sheba Medical Center - Clinical Microbiology

Moriah Bergwerk

Chaim Sheba Medical Center - Infection Prevention & Control Unit

Marc Lipsitch

Harvard T.H. Chan School of Public Health - Center for Communicable Disease Dynamics

Eyal Leshem

Chaim Sheba Medical Center - Infectious Disease Unit

Rebecca Kahn

Harvard T.H. Chan School of Public Health - Center for Communicable Disease Dynamics

Yaniv Lustig

Chaim Sheba Medical Center - Central Virology Laboratory

Carmit Cohen

Chaim Sheba Medical Center - Infection Prevention & Control Unit

Ram Doolman

Chaim Sheba Medical Center - Laboratory Division

Arnona Ziv

Chaim Sheba Medical Center - Bio-statistical and Bio-mathematical Unit

Ilya Novikov

Chaim Sheba Medical Center - Gertner Institute for Epidemiology & Health Policy

Carmit Rubin

Chaim Sheba Medical Center - Bio-statistical and Bio-mathematical Unit

Irena Gimpelevich

Chaim Sheba Medical Center - Gertner Institute for Epidemiology & Health Policy

Amit Huppert

Chaim Sheba Medical Center - Bio-statistical and Bio-mathematical Unit

Galia Rahav

Chaim Sheba Medical Center - Infectious Diseases Unit

Arnon Afek

Chaim Sheba Medical Center - General Management

Yitshak Kreiss

Chaim Sheba Medical Center - General Management

More...

Abstract

Background: BNT162b2 was shown to be 92% effective in preventing COVID-19. Prioritizing vaccine rollout, and achievement of herd immunity depend on SARS-CoV-2 transmission reduction. The vaccine’s effect on infectivity is thus a critical priority.

Methods: In a cohort of all 9650 HCW of a large single tertiary medical center, we calculated the prevalence of positive SAR-CoV-2 qRT-PCR cases with an asymptomatic presentation, tested following known or presumed exposure and the infectious subset (N-gene-Ct-value<30) of these and the prevalence of never-symptomatic infections. Additionally, infection incidence rates were calculated for symptomatic cases and infectious (Ct<30) cases. Vaccine effectiveness within three months of vaccine rollout was measured as one minus the relative risk or rate ratio, respectively. To further assess infectiousness, we compared the mean Ct-value and the proportion of infections with a positive SARS-CoV-2 antigen test of vaccinated vs. unvaccinated. The correlation between IgG levels within the week before detection and Ct level was assessed.

Findings: Reduced prevalence among fully vaccinated HCW was observed for (i) infections detected due to exposure, with asymptomatic presentation (VE(i)=65.1%, 95%CI 45-79%), (ii) the presumed infectious (Ct<30) subset of these (VE(ii)=69.6%, 95%CI 43-84%) (iii) never-symptomatic infections (VE(iii)=72.3%, 95%CI 48-86%), and (iv) the presumed infectious (Ct<30) subset (VE(iv)=83.0%, 95%CI 51-94%).Incidence of (v) symptomatic and (vi) symptomatic-infectious cases was significantly lower among fully vaccinated vs. unvaccinated individuals (VE(v)= 89.7%, 95%CI 84-94%, VE(vi)=88.1%, 95%CI 80-95%).The mean Ct-value was significantly higher in vaccinated vs. unvaccinated (27.3±1.2 vs. 22.2±1.0, p<0.001) and the proportion of positive SARS-CoV-2 antigen tests was also significantly lower among vaccinated vs. unvaccinated PCR-positive HCW (80% vs. 31%, p<0.001). Lower infectivity was correlated with higher IgG concentrations (R=0.36, p=0.01).

Interpretation: These results suggest that BNT162b2 is moderately to highly effective in reducing infectivity, via preventing infection and through reducing viral shedding. 

Funding: Sheba Medical Center, Israel

Declaration of Interest: All authors declare they have no competing interests

Ethical Approval: The Sheba Ethical committee, reviewed the protocol and approved the
study.

Suggested Citation

Regev-Yochay, Gili and Amit, Sharon and Bergwerk, Moriah and Lipsitch, Marc and Leshem, Eyal and Kahn, Rebecca and Lustig, Yaniv and Cohen, Carmit and Doolman, Ram and Ziv, Arnona and Novikov, Ilya and Rubin, Carmit and Gimpelevich, Irena and Huppert, Amit and Rahav, Galia and Afek, Arnon and Kreiss, Yitshak, Decreased Infectivity Following BNT162b2 Vaccination. Available at SSRN: https://ssrn.com/abstract=3815668 or http://dx.doi.org/10.2139/ssrn.3815668

Gili Regev-Yochay (Contact Author)

Tel-Aviv University - Sackler Faculty of Medicine ( email )

Tel-Aviv
Israel

Sharon Amit

Sheba Medical Center - Clinical Microbiology ( email )

Tel Hashomer
Ramat-Gan
Israel

Moriah Bergwerk

Chaim Sheba Medical Center - Infection Prevention & Control Unit ( email )

Tel Hashomer
Ramat-Gan
Israel

Marc Lipsitch

Harvard T.H. Chan School of Public Health - Center for Communicable Disease Dynamics ( email )

677 Huntington Avenue
Boston, MA MA 02115
United States

Eyal Leshem

Chaim Sheba Medical Center - Infectious Disease Unit ( email )

Tel Hashomer
Ramat-Gan
Israel

Rebecca Kahn

Harvard T.H. Chan School of Public Health - Center for Communicable Disease Dynamics ( email )

Boston, MA
United States

Yaniv Lustig

Chaim Sheba Medical Center - Central Virology Laboratory ( email )

Ramat-Gan
Israel

Carmit Cohen

Chaim Sheba Medical Center - Infection Prevention & Control Unit ( email )

Tel Hashomer
Ramat-Gan
Israel

Ram Doolman

Chaim Sheba Medical Center - Laboratory Division ( email )

Tel Hashomer
Ramat-Gan
Israel

Arnona Ziv

Chaim Sheba Medical Center - Bio-statistical and Bio-mathematical Unit ( email )

Tel Hashomer
Ramat-Gan
Israel

Ilya Novikov

Chaim Sheba Medical Center - Gertner Institute for Epidemiology & Health Policy ( email )

Tel Hashomer
Ramat-Gan
Israel

Carmit Rubin

Chaim Sheba Medical Center - Bio-statistical and Bio-mathematical Unit ( email )

Tel Hashomer
Ramat-Gan
Israel

Irena Gimpelevich

Chaim Sheba Medical Center - Gertner Institute for Epidemiology & Health Policy ( email )

Tel Hashomer
Ramat-Gan
Israel

Amit Huppert

Chaim Sheba Medical Center - Bio-statistical and Bio-mathematical Unit ( email )

Tel Hashomer
Ramat-Gan
Israel

Galia Rahav

Chaim Sheba Medical Center - Infectious Diseases Unit ( email )

Tel-Hashomer
Israel

Arnon Afek

Chaim Sheba Medical Center - General Management ( email )

Tel Hashomer
Ramat-Gan
Israel

Yitshak Kreiss

Chaim Sheba Medical Center - General Management ( email )

Tel Hashomer
Ramat-Gan
Israel

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