Press Release

Sheba Medical Center Study Reports Effectiveness of Fourth Covid Vaccine Dose Over Six-Month Timeframe

Research Published in New England Journal of Medicine Demonstrates Significant Increase in Protection from Third and Fourth Doses. Study Pinpoints Optimum Timing for Administering Covid Booster Vaccines.

RAMAT GAN, Israel – November 10, 2022 – Sheba Medical Center, Israel’s largest medical center and a Newsweek top-10 ranked world’s best hospital for the last four years, published a study today in the New England Journal of Medicine demonstrating the necessity for mRNA Covid vaccine booster doses, and pinpointing the ideal timing for administering them. The research, led by Dr. Michal Canetti at Columbia University, New York and Professor Gili Regev-Yochay, studied the effectiveness of the BNT162b2 vaccine (Pfizer–BioNTech) in Sheba Medical Center healthcare workers, concluded that the protection achieved by a third or fourth vaccine dose was significantly stronger than that of two doses alone.

The study measured both immune response and the effectiveness of the vaccine in preventing Omicron infection. Results displayed that the protection achieved by a third or fourth vaccine dose is much higher than two doses alone. Further observations concluded that the third and fourth doses induced a similar immune response, peaking within a month of being administered and waning gradually over about four months. The study also determined that the overall vaccine effectiveness in preventing Omicron infection was 40% during the first six months, with rates reaching as high as 50% during the initial months.

The peer reviewed study was conducted on a cohort of healthcare workers at Sheba Medical Center, who had not previously contracted the coronavirus. Researchers tested the immune response of ~6,000 participants by measuring antibody levels monthly, and comparing them after the second, third, and fourth vaccinations.

The study concludes that the correlation between antibody levels and risk infection, as well as the waning immunogenic response within four months of receiving an mRNA Covid vaccine, demonstrates the need to administer boosters seasonally, like the influenza vaccine, or to be timed to coincide with disease waves.

“Our latest research sheds further light on the direct relationship between antibodies and protection against coronavirus infection, including Omicron,” said Professor Gili Regev-Yochay, Director of the Infectious Diseases Unit at Sheba Medical Center. “With protection clearly waning after four months, individuals and health systems must plan their booster timing wisely, taking into consideration not only surges in infection but also personal medical conditions, upcoming events and travel, and higher-risk seasons.”

About Sheba medical Center

The largest and most comprehensive medical center in the Middle East, Sheba Medical Center, Tel  Hashomer is generating global impact through its medical care, research and healthcare transformation.  Sheba’s City of Health boasts an acute-care hospital, rehabilitation hospital, research and innovation  hubs, medical simulation center and center for disaster response on one comprehensive campus in the  center of Israel. A university teaching hospital affiliated with the Sackler School of Medicine at Tel-Aviv  University, Sheba is shaping the future of healthcare, educating the next generation of care providers.  Sheba serves as a true hospital without borders, welcoming patients and healthcare professionals from  all over the world and consistently providing the highest-level medical care to all in need. Sheba has  been ranked a top-ten hospital in the world by Newsweek four years in a row (2019, 2020, 2021, 2022). 

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Steve Walz

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