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Decreased infectivity following BNT162b2 vaccination: A prospective cohort study in Israel
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...
Autores principales: | , , , , , , , , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Elsevier
2021
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8261633/ https://www.ncbi.nlm.nih.gov/pubmed/34250518 http://dx.doi.org/10.1016/j.lanepe.2021.100150 |
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author | Regev-Yochay, Gili Amit, Sharon Bergwerk, Moriah Lipsitch, Marc Leshem, Eyal Kahn, Rebecca Lustig, Yaniv Cohen, Carmit Doolman, Ram Ziv, Arnona Novikov, Ilya Rubin, Carmit Gimpelevich, Irena Huppert, Amit Rahav, Galia Afek, Arnon Kreiss, Yitshak |
author_facet | Regev-Yochay, Gili Amit, Sharon Bergwerk, Moriah Lipsitch, Marc Leshem, Eyal Kahn, Rebecca Lustig, Yaniv Cohen, Carmit Doolman, Ram Ziv, Arnona Novikov, Ilya Rubin, Carmit Gimpelevich, Irena Huppert, Amit Rahav, Galia Afek, Arnon Kreiss, Yitshak |
author_sort | Regev-Yochay, Gili |
collection | PubMed |
description | 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 |
format | Online Article Text |
id | pubmed-8261633 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | Elsevier |
record_format | MEDLINE/PubMed |
spelling | pubmed-82616332021-07-07 Decreased infectivity following BNT162b2 vaccination: A prospective cohort study in Israel Regev-Yochay, Gili Amit, Sharon Bergwerk, Moriah Lipsitch, Marc Leshem, Eyal Kahn, Rebecca Lustig, Yaniv Cohen, Carmit Doolman, Ram Ziv, Arnona Novikov, Ilya Rubin, Carmit Gimpelevich, Irena Huppert, Amit Rahav, Galia Afek, Arnon Kreiss, Yitshak Lancet Reg Health Eur Research Paper 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 Elsevier 2021-07-07 /pmc/articles/PMC8261633/ /pubmed/34250518 http://dx.doi.org/10.1016/j.lanepe.2021.100150 Text en © 2021 The Author(s) https://creativecommons.org/licenses/by-nc-nd/4.0/This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). |
spellingShingle | Research Paper Regev-Yochay, Gili Amit, Sharon Bergwerk, Moriah Lipsitch, Marc Leshem, Eyal Kahn, Rebecca Lustig, Yaniv Cohen, Carmit Doolman, Ram Ziv, Arnona Novikov, Ilya Rubin, Carmit Gimpelevich, Irena Huppert, Amit Rahav, Galia Afek, Arnon Kreiss, Yitshak Decreased infectivity following BNT162b2 vaccination: A prospective cohort study in Israel |
title | Decreased infectivity following BNT162b2 vaccination: A prospective cohort study in Israel |
title_full | Decreased infectivity following BNT162b2 vaccination: A prospective cohort study in Israel |
title_fullStr | Decreased infectivity following BNT162b2 vaccination: A prospective cohort study in Israel |
title_full_unstemmed | Decreased infectivity following BNT162b2 vaccination: A prospective cohort study in Israel |
title_short | Decreased infectivity following BNT162b2 vaccination: A prospective cohort study in Israel |
title_sort | decreased infectivity following bnt162b2 vaccination: a prospective cohort study in israel |
topic | Research Paper |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8261633/ https://www.ncbi.nlm.nih.gov/pubmed/34250518 http://dx.doi.org/10.1016/j.lanepe.2021.100150 |
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