Pfizer COVID-19 booster shot reduces severity of disease, study suggests

By Jennifer Ferreira

Click here for updates on this story

    TORONTO (CTV Network) — New research into the effectiveness of the Pfizer-BioNTech COVID-19 booster shot suggests getting a third dose significantly reduces the risk of disease-related hospitalization and death.

Conducted by Israel’s Clalit Research Institute in collaboration with researchers at Harvard University, the study compared data from 728,321 individuals age 12 and older who received a third dose of the Pfizer vaccine with the same number of people who received only two doses at least five months prior.

According to the study, receiving the Pfizer booster shot reduced COVID-related hospitalization by 93 per cent, COVID-related death by 81 per cent, and severe COVID-19 illness by 92 per cent, compared with receiving just two doses.

“These results show convincingly that the third dose of the vaccine is highly effective against severe COVID-19-related outcomes in different age groups and population subgroups, one week after the third dose,” said Ran Balicer, senior author of the study and director of the Clalit Research Institute, in a press release.

The study took place in Israel from July 30 through Sept. 23. Researchers looked at the number of COVID-19-related hospital admissions, deaths and severity of disease based on criteria from the U.S. National Institutes of Health. The study also found that a third dose of the Pfizer vaccine reduced the risk of COVID-19 infection by 88 per cent.

“To date, one of the main drivers of vaccine hesitancy has been a lack of information regarding the effectiveness of the vaccine,” said Ben Reis, director of the Predictive Medicine Group at Harvard Medical School and the Boston Children’s Hospital Computational Health Informatics Program, in the press release. “This careful epidemiological study provides reliable information on third-dose vaccine effectiveness, which we hope will be helpful to those who have not yet decided about vaccination with a third dose.”

Researchers, however, do note that the rate of COVID-19 hospitalization and severe disease among those age 16 to 39 was too small to determine the booster’s effectiveness. The study also did not include health-care workers, those living in long-term care facilities or people medically confined to their homes. These groups are often more vulnerable to contracting the disease, and likely to be targeted early to receive a booster shot.

At the time of the study, Israel was undergoing its fourth wave largely driven by the Delta variant, which continues to be a concern in Canada today.

The National Advisory Committee on Immunization suggested on Oct. 29 that provinces offer mRNA vaccine booster shots to Canadians who are aged 70 and up, along with people who received two doses of the AstraZeneca vaccine or one dose of the Janssen vaccine and adults in First Nations, Inuit and Metis communities, at least six months after their primary vaccine course. Provinces across Canada have already begun outlining their third-dose policy for immunocompromised people.

Please note: This content carries a strict local market embargo. If you share the same market as the contributor of this article, you may not use it on any platform.

Sonja Puzic
sonja.puzic@bellmedia.ca