Scientists of the Research Institute Cllyt (Israel) and Harvard University (USA) have determined the effectiveness of the third dose of the Pfizer / Biontech vaccine against the SARS-COV-2 coronavirus delta version. The results prove that the third dose of vaccine prevents severe outcomes related to COVID-19, after a week after vaccination. Results are published in the LanCet magazine. Briefly about scientific work is described in a press release on MedicalXpress.
The study was conducted from July 30, 2021 to September 23, 2021, which coincided with the fourth wave of coronavirus infection in Israel, during which the Delta variant (B.1.617.2) became the dominant strain in the country. Experts analyzed 728,321 people aged 12 years and older who received the third dose of BNT162B2 vaccine. Each patient was compared with a person who received only two vaccines.
It turned out that compared to people who received only two doses of five months earlier, in patients who received three doses of vaccine, the risk of hospitalization related to COVID-19 was 93 percent lower, the risk of severe disease COVID-19 decreased by 92 percent, and the risk of death associated with COVID-19 was 81 percent lower. At the same time, the effectiveness of the vaccine is the same for different floors, age groups (40-69 and more than 70 years) and did not depend on the number of concomitant diseases.