The BNT162b2 vaccine effectiveness against new COVID-19 cases and complications of breakthrough cases: A nation-wide retrospective longitudinal multiple cohort analysis using individualised data

Abstract

Background: The rapid vaccination campaign against COVID-19 in Israel relied on the BNT162b2 vaccine. We performed a longitudinal analysis of multiple cohorts, using individual data, to evaluate the effectiveness of the vaccine against new and breakthrough cases.

Methods: We estimated vaccine effectiveness (VE) for 27 consecutive cohorts, each comprised of individuals vaccinated on specific days. VE against new COVID-19 cases was evaluated for five SARS-CoV-2-related outcomes: infection, symptomatic disease, hospitalisation, severe/critical disease and death. For breakthrough cases, rate reduction was evaluated for hospitalisation, severe/critical disease and death. Outcomes were evaluated at predetermined time-periods after vaccination, the last one dedicated to individuals who became SARS-CoV-2-positive 22-28 days after the second dose.

Findings: The highest VE estimates against new cases in ≥16 year old individuals, for all outcomes, were reached at the 15-21 day period after the second dose, ranging between 97.7% (95% CI: 95.9-98.7%) for deaths and 98.6% (95% CI: 97.8-99.1%) for severe/critical disease. VE estimates of the 14-20 day period after the first dose ranged between 54.3% (95% CI: 50.6-57.8%) for infection and 77.3% (95% CI: 71.2-82.1%) for severe/critical disease. VE rose more slowly among ≥80 year old individuals. Rate reductions of breakthrough complications were highest at the 22-28 day period after the second dose, ranging between 47.4% (95% CI: 4.3-71.2%) for death and 66.2% (95% CI: 44.2-79.6%) for severe/critical disease.

Interpretation: The BNT162 vaccine is highly effective in preventing new SARS-CoV-2 cases. Among ≥80 year old individuals, high effectiveness develops more slowly. In breakthrough cases, vaccination reduces complications and death.

Funding: None.

Keywords: Breakthrough cases; COVID-19; SARS-CoV-2; Vaccine effectiveness.

Fig. 1

a. Epidemic curve of SARS-CoV-2 cases in Israel, with highlights of vaccination dates for the 27 cohorts of our study. b. Graphic representation of the first vaccine dose VE evaluation process for an individual cohort. The panel presents cohort No. 1 that received the first dose on 21 December 2020. Light blue bars represent the number of individuals who received the first vaccine dose each day; Orange asterix represents the date the first-dose cohort No. 1 received the first vaccine dose. C. Graphic representation of second dose VE evaluation process of an individual cohort. The panel presents cohort No. 1 that received the second dose on January 11, 2020. Dark blue bars represent the number of individuals who received the second vaccine dose each day; Orange asterix represents the date the second-dose cohort No. 1 received the second vaccine dose (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.).

Fig. 2

Adjusted vaccine effectiveness and 95% CI of 27 cohorts against SARS-CoV-2-associated infection (panels a, f, k), symptomatic disease (panels b, g, l), hospitalisations (panels c, h, m), severe/critical disease (panels d, i, n) and death (panels e, j, o). Panels a-e represent outcomes that occurrred on days 14–20 after the first vaccine dose; panels f–j represent outcomes that occurred 8–14 after the second dose; panels k–o represent outcomes that occurred 15–21 after the second vaccine dose dose. Statistical adjustment was performed for age and sex. Asterix (*) represents abrreviation for severe/critical disease.