Effectiveness of a third dose of the BNT162b2 mRNA COVID-19 vaccine for preventing severe outcomes in Israel : an observational study

Copyright © 2021 Elsevier Ltd. All rights reserved..

BACKGROUND: Many countries are experiencing a resurgence of COVID-19, driven predominantly by the delta (B.1.617.2) variant of SARS-CoV-2. In response, these countries are considering the administration of a third dose of mRNA COVID-19 vaccine as a booster dose to address potential waning immunity over time and reduced effectiveness against the delta variant. We aimed to use the data repositories of Israel's largest health-care organisation to evaluate the effectiveness of a third dose of the BNT162b2 mRNA vaccine for preventing severe COVID-19 outcomes.

METHODS: Using data from Clalit Health Services, which provides mandatory health-care coverage for over half of the Israeli population, individuals receiving a third vaccine dose between July 30, 2020, and Sept 23, 2021, were matched (1:1) to demographically and clinically similar controls who did not receive a third dose. Eligible participants had received the second vaccine dose at least 5 months before the recruitment date, had no previous documented SARS-CoV-2 infection, and had no contact with the health-care system in the 3 days before recruitment. Individuals who are health-care workers, live in long-term care facilities, or are medically confined to their homes were excluded. Primary outcomes were COVID-19-related admission to hospital, severe disease, and COVID-19-related death. The third dose effectiveness for each outcome was estimated as 1 - risk ratio using the Kaplan-Meier estimator.

FINDINGS: 1 158 269 individuals were eligible to be included in the third dose group. Following matching, the third dose and control groups each included 728 321 individuals. Participants had a median age of 52 years (IQR 37-68) and 51% were female. The median follow-up time was 13 days (IQR 6-21) in both groups. Vaccine effectiveness evaluated at least 7 days after receipt of the third dose, compared with receiving only two doses at least 5 months ago, was estimated to be 93% (231 events for two doses vs 29 events for three doses; 95% CI 88-97) for admission to hospital, 92% (157 vs 17 events; 82-97) for severe disease, and 81% (44 vs seven events; 59-97) for COVID-19-related death.

INTERPRETATION: Our findings suggest that a third dose of the BNT162b2 mRNA vaccine is effective in protecting individuals against severe COVID-19-related outcomes, compared with receiving only two doses at least 5 months ago.

FUNDING: The Ivan and Francesca Berkowitz Family Living Laboratory Collaboration at Harvard Medical School and Clalit Research Institute.

Errataetall:

CommentIn: Lancet. 2021 Dec 4;398(10316):2055-2057. - PMID 34756185

Medienart:

E-Artikel

Erscheinungsjahr:

2021

Erschienen:

2021

Enthalten in:

Zur Gesamtaufnahme - volume:398

Enthalten in:

Lancet (London, England) - 398(2021), 10316 vom: 04. Dez., Seite 2093-2100

Sprache:

Englisch

Beteiligte Personen:

Barda, Noam [VerfasserIn]
Dagan, Noa [VerfasserIn]
Cohen, Cyrille [VerfasserIn]
Hernán, Miguel A [VerfasserIn]
Lipsitch, Marc [VerfasserIn]
Kohane, Isaac S [VerfasserIn]
Reis, Ben Y [VerfasserIn]
Balicer, Ran D [VerfasserIn]

Links:

Volltext

Themen:

BNT162 Vaccine
Journal Article
N38TVC63NU
Observational Study

Anmerkungen:

Date Completed 14.12.2021

Date Revised 21.12.2022

published: Print-Electronic

CommentIn: Lancet. 2021 Dec 4;398(10316):2055-2057. - PMID 34756185

Citation Status MEDLINE

doi:

10.1016/S0140-6736(21)02249-2

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM332941485