Infectious Disease
Pfizer Booster Lowers Risk of Mortality and Serious Illness From COVID-19 in Israeli Studies
December 08, 2021
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Arbel and Bar-On do not report any relevant financial information. Please refer to the studies for all relevant financial information from the other authors.
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Adults 50 years of age or older who received a booster dose of Pfizer-BioNTech at least 5 months after a second dose of vaccine had a 90% lower COVID-19 death rate than those who did not receive the booster dose.
The results, published in the New England Journal of Medicine, date back to before the Omicron variant was first discovered.
Arbel R. et al. N Engl J Med. 2021; doi: 10.1056 / NEJMoa2115624.
The evidence generated in the study “shows a significant life-saving potential through the provision of the booster”, Ronen Arbel, PhD, wrote a health researcher at Clalit Health Services in Tel Aviv, Israel, and colleagues.
Arbel and colleagues conducted an observational study in Israel that included 843,208 adults aged 50 and over. All participants were members of the Clalit Health Service and were vaccinated with two doses of the Pfizer vaccine. Of these, 90% received the booster dose during the 54-day study period from August 6th to September 29th. The average age of the participants was 68.5 years. Common comorbidities were high blood pressure (46%), obesity (33%) and diabetes (29%).
Mortality estimates
A total of 65 participants in the booster group (0.16 deaths per 100,000 people per day) and 137 participants in the non-booster group (2.98 deaths per 100,000 people per day) died of COVID-19 (adjusted HR = 0.1; 95% CI, 0.07-0.14), according to Arbel and colleagues. Of a certain subgroup of participants aged 65 years or older, 60 of 470,808 participants in the booster group and 123 of 35,208 participants in the non-booster group died of COVID-19 (aHR = 0.09; 95% CI, 0.07-0.13). Similarly, among participants under 65 years of age, the booster group had a lower mortality rate than the non-booster group (aHR = 0.13; 95% CI, 0.04-0.4). When Arbel and colleagues stratified by gender, they observed fewer deaths in men and women in the booster group than in those who did not receive the booster group.
Infection and serious illness
A separate study published in the New England Journal of Medicine showed lower rates of confirmed infection and serious illness in people 16 years of age or older in Israel who received the Pfizer booster. Special, YesInot M. Bar-On, MSc, from the Weizmann Institute of Science in Rehovot, Israel, and colleagues observed that the rate of confirmed infections in the booster group was about ten times lower than in the non-booster group. The researchers extracted data from more than 4.6 million people who had received both doses of the Pfizer vaccine at least 5 months previously. The study recorded the results from July 30th to October 10th.
Overall, the rate of serious illnesses in the booster group was 17.9 times lower than in the non-booster group in those over 60 years of age (95% CI 15.1-21.2) and in those 40- to 59-year-olds 21.7 times lower. Also, the rate of COVID-19-associated deaths among those over 60 who received a booster vaccination was 14.7 times lower.
“Booster vaccination programs can provide a way to control transmission without costly social distancing and quarantines,” wrote Bar-On and colleagues. “Our results confirm the short-term effectiveness of the booster vaccination compared to the currently dominant delta variant in people aged 16 and over.”
The study results were published shortly after new data from Pfizer and BioNTech were released, showing that a booster dose of their vaccine appeared to offer improved protection against the fast-spreading variant of Omicron. According to a company press release, a laboratory study showed that participants who received two doses had an average of more than 25-fold reduction in neutralization titers against Omicron compared to the original virus 3 weeks after the second dose. However, sera collected from humans one month after a third dose neutralized the variant after two doses to levels comparable to the wild-type strain, the companies said, and there was evidence that two doses were still before Protect more serious infections.
References:
Arbel R. et al. N Engl J Med. 2021; doi: 10.1056 / NEJMoa2115624.
Bar-On YM et al. N Engl J Med. 2021; doi: 10.1056 / NEJMoa2115926.
Pfizer. Pfizer and BioNTech provide an update on the omicron variant. https://www.pfizer.com/news/press-release/press-release-detail/pfizer-and-biontech-provide-update-omicron-variant. Accessed December 8, 2021.
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