The Claritt Research Institute, in collaboration with researchers at Harvard University, is analyzing one of the world’s largest integrated health records databases to study the effectiveness of the Pfizer / BioNTech BNT162B2 vaccine against the SARS-CoV-2 delta among adolescents. The study provides the highest peer-reviewed evaluation of the efficacy of the COVID-19 vaccine among adolescents in a national mass vaccination setting and the first such study where the Delta variant is dominant. The study was conducted in Israel, an early world leader in the number of vaccinations against COVID-19.
The results of this study confirm and complement the previously reported findings of a randomized Phase III clinical trial of Pfizer / BioNTech, which focused on symptomatic infections in the face of non-Delta variants and with 1,983 vaccinated adolescents aged 12 years and older. For 15 years, he could not accurately assess the effectiveness of the vaccine. The large size of the present study allows a more accurate assessment of the effectiveness of the vaccine over different periods of time.
The study was conducted from June 8, 2021 to September 14, 2021. It coincided with the fourth wave of Israeli coronavirus infection and disease, during which the Delta variant (B.1.617.2) was the dominant strain in the country for new infections.
The researchers reviewed data from 94,354 vaccinated adolescents aged 12 to 18 years. These teens were carefully matched with 94,354 unvaccinated adolescents based on an extensive set of demographic, geographic, and health-related characteristics related to risk of infection, risk of serious illness, health status, and health seeking behaviors. Individuals were assigned to each group dynamically based on the changing vaccination status (13,423 individuals moved from the unvaccinated cohort to the vaccinated cohort during the study). Numerous susceptibility analyzes have been performed to ensure that the calculated efficacy of the vaccine is resistant to potential deviations.
The results showed that in fully vaccinated adolescents (7 to 21 days after the second dose) the risk of symptomatic COVID-19 was reduced by 93% compared to unvaccinated subjects, while the risk of documented infection was reduced by 90%. In the period immediately before the second dose (14-20 days after the first dose), the effectiveness of the vaccine was lower, but still significant – the risk of symptomatic COVID-19 decreased by 57% in vaccinated individuals and the risk of documented infection by 59%. . There are insufficient data to assess a reduction in the incidence of serious illness, hospitalization and mortality, as these results are rare in adolescents.
The study was conducted by Dr. Noam Barda, Dr. Noah Dagan, Michael Leszczynski, Dr. Eldad Kepten and Prof. Ran Balisser of the Clalit Research Institute, as well as Prof. Miguel Hernan and Prof. Mark Lipsich of the Harvard TH School of public health Chan and Prof. Ben Rice of Boston Children’s Hospital and Harvard Medical School.
“The widespread national distribution of the Israeli vaccination campaign against COVID-19 among adolescents at the very beginning of the delta wave provided the Clalit Research Institute with a unique opportunity to evaluate the effectiveness of the delta vaccine against adolescents in real life through its rich and comprehensive digital datasets. “These results show convincingly that one week after the second dose, this vaccine is highly effective in adolescents against symptomatic COVID.” 19 and against all documented infections. These data should facilitate informed individual risk-benefit decisions and, in our view, provide a strong argument in favor of the possibility of vaccination, especially in countries where the virus is currently widespread, ”added Prof. Balisser, who is also chairman of the Israeli National Expert Advisory Team on COVID-19 Response.
Professor Ben Rice, director of the Predictive Medicine Group at Boston Children’s Hospital’s Computational Health Information Program and Harvard Medical School, said: “To date, one of the main drivers of vaccine fluctuations is the lack of information on the effectiveness of this careful epidemiological study. provides reliable information on the effectiveness of the vaccine, which we hope will be useful for those who have not yet decided on a vaccination. “
This study is a perfect example of how randomized trials and healthcare databases complement each other. The adolescent-oriented trial of Pfizer / BioNTech provided convincing evidence of its effectiveness in preventing symptomatic infection, but estimates of severe disease and age-specific groups were very inaccurate. This analysis of Clalit’s high-quality database mimics the design of the initial trial, uses its findings as a reference, and extends them to confirm the effectiveness of the vaccine in adolescents. This combination of evidence from randomized trials and observations is a model for effective medical research, something that is particularly important during COVID. “
Prof. Miguel Hernan, Director, CAUSALab and Professor, Harvard School of Public Health TH Chan
Prof. Mark Lipsic, director of the Center for the Dynamics of Infectious Diseases and a professor at the TH Chan Harvard School of Public Health, said: “In all studies on the effectiveness of the vaccine, the main challenge is to ensure that similar in other characteristics that can predict whether they become infected or ill. This is particularly difficult in the context of a rapidly growing, age-targeted vaccine campaign. Clalit’s exclusive database has made it possible to develop a study to meet these challenges in a way that provides great confidence in the findings of the study. “
Clalitt Research Institute
Reference in the magazine:
Rice, BY, and others. (2021) Efficacy of the BNT162b2 vaccine against the delta variant in adolescents. New England Journal of Medicine. doi.org/10.1056/NEJMc2114290.