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Cited by 111SARS-CoV-2 and COVID-19 ResearchCOVID-19 epidemiological studiesVaccine Coverage and Hesitancy

Decreased infectivity following BNT162b2 vaccination: A prospective cohort study in Israel

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Regev-Yochay, Gili, Amit, Sharon, Bergwerk, Moriah, Lipsitch, Marc, Leshem, Eyal, Kahn, Rebecca, Lustig, Yaniv, Cohen, Carmit +9 more·2021·The Lancet Regional Health - Europe
DOI 10.1016/j.lanepe.2021.100150PMC PMC8261633
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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: Among all 9650 HCW of a large tertiary medical center in Israel, we calculated the prevalence of positive SARS-CoV-2 qRT-PCR cases with asymptomatic presentation, tested following known or presumed exposure and the infectious subset (N-gene-Ct-value<30) of these. 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.

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  • The breakthrough cases were less contagious than unvaccinated persons, as supported by no secondary infections and previous reports.

    “However, no secondary infections were traced back to any of the breakthrough cases, which supports the inference that these workers were less contagious than unvaccinated persons, as has been reported previously.4,5,17,18”

    From Covid-19 Breakthrough Infections in Vaccinated Health Care Workers (2021) · cites this paper as [4]

  • The BNT162b2 vaccine reduces the incidence of asymptomatic infection and associated infectivity.

    “The vaccine has also been shown to reduce the incidence of asymptomatic infection and the associated infectivity.4,5”

    From Covid-19 Breakthrough Infections in Vaccinated Health Care Workers (2021) · cites this paper as [4]

  • Vaccine-induced immunity is greatly protective against clinical disease but somewhat less protective against infection and infectivity.

    “This result may eventually be even more important, since vaccine-induced immunity has been shown to be greatly protective against clinical disease but somewhat less protective against both infection and infectivity.4”

    From Covid-19 Breakthrough Infections in Vaccinated Health Care Workers (2021) · cites this paper as [4]

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Research works printed but not linked: 1

  1. Chodcik G, Tene L, Patalon T, et al. The effectiveness of the first dose of BNT162 b 2 vaccine in reducing SARS-CoV-2 infection 13-24 days after immunization: real- world evidence. medRxiv 2021 published online Jan 29. doi: 10.1101/2021. 01.27.21250612. · DOI

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Authors
Regev-Yochay, G., Amit, S., Bergwerk, M., Lipsitch, M., Leshem, E., Kahn, R., Lustig, Y., Cohen, C., Doolman, R., Ziv, A., Novikov, I., Rubin, C., Gimpelevich, I., Huppert, A., Rahav, G., Afek, A., & Kreiss, Y.
Affiliations
  • Sheba Medical Center (IL)
  • Tel Aviv University (IL)
ORCID
Venue
The Lancet Regional Health - Europe
Publisher
Elsevier BV
Published
2021-08
Volume
7
Pages
100150
ISSN
2666-7762 (ISSN-L)
DOI
10.1016/j.lanepe.2021.100150
PMC
PMC8261633
OpenAlex
W3180361036
Cited by
111
References
38
Citations by year
2026: 1 · 2025: 4 · 2024: 4 · 2023: 18 · 2022: 54 · 2021: 30
FWCI
8.39
Type
journal article
Language
en
Open access
Licence
Locations
  • The Lancet Regional Health - Europe (publishedVersion, cc-by-nc-nd)
  • PubMed Central (publishedVersion, cc-by-nc-nd)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • ImmPort
Funders
  • National Cancer Institute (U01CA261277)
  • National Institute of Allergy and Infectious Diseases (T32AI007535)
Topics
  • Health Sciences › Medicine › Infectious Diseases › SARS-CoV-2 and COVID-19 Research
  • Physical Sciences › Mathematics › Modeling and Simulation › COVID-19 epidemiological studies
  • Social Sciences › Health › Vaccine Coverage and Hesitancy
Keywords
BNT162b2, COVID-19 vaccine effectiveness, infectiousness, SARS-CoV-2, healthcare workers, asymptomatic infection, cycle threshold, viral load, IgG, vaccine rollout, herd immunity, SARS-CoV-2 antigen test, Israel, vaccine hesitancy, breakthrough infection

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