A third dose of the Pfizer coronavirus vaccine has been shown to reduce COVID-19-related hospitalization, severe disease and death in a study of more than 728,000 people in Israel.
The study, published in the Lancet and done in collaboration with Harvard University, matched 728,321 people who received a third dose of the Pfizer/BioNTech COVID-19 vaccine with an equal number of people who had received two doses of the vaccine at least five months prior.
Those who received the third dose saw COVID-19-related hospitalizations decrease by 93%, cases of severe COVID-19 disease decrease by 92% and COVID-19-related deaths fall by 81%, compared with those who received only two doses at least five months ago.
The study, which was conducted between July 30 and Sept 23, is peer-reviewed. Those in the study were matched for age, gender, comorbidities, health status and other factors.
“The extensive nationwide rollout of Israel’s third-dose ‘booster’ COVID-19 vaccination campaign provided the Clalit Research Institute with a unique opportunity to assess, through its rich and comprehensive digital datasets, the effectiveness of the third dose in a real-world setting against the less common but severe complications of COVID-19,” said Prof. Ran Balicer, senior author of the study, director of the Clalit Research Institute and chief innovation officer for Clalit.
“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,” Balicer added.
The study coincided with the rise of the delta variant of the infection in Israel. It included participants aged 12 and above.
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