The first large-scale real-world study of the efficacy of booster (reminder doses after second dose) vaccines against COVID-19 has been completed. In this study, it was determined that up to 93 percent protection was provided even against the Delta variant. Of course, while billions of people are yet to be vaccinated, there is considerable debate about how ethical and reasonable it is to use the limited vaccine to give third doses to people in rich countries. But the findings of this study question whether Delta can be brought under control using existing mRNA vaccines rather than requiring new specifically targeted versions.
Israel is a country that received mRNA vaccines much earlier than other countries. This helped him control a winter outbreak and temporarily reduced infections to negligible levels. However, by July the Delta was spreading widely. Infections then set national records, but death rates were less than half of the previous worst.
Israel tried the same approach again on July 13, long before anyone else, by starting booster vaccines for those who were already fully vaccinated and collecting a wealth of data. The Lancet has now published an analysis examining this rich source of information. While the raw numbers already suggest that booster doses work, the research is controlling for confounding factors such as pre-existing conditions.
The study is based on the period from July 30 to September 23 this year and includes much of Israel’s fourth wave, which peaked at around 10,000 cases and 30 deaths per day in early September. Almost all infections recorded during this wave were of the Delta variant.
The authors compared 728,321 people who received the third dose of Pfizer vaccine with the same number of people who had their second Pfizer injection at least five months ago but had not yet received a boost. The second group was carefully selected to be as close as possible to the first group in terms of characteristics such as age, gender, location, health status, and known risk-taking and risk-avoidance behavior.
The most impressive finding was that a little more than a week after receiving the booster vaccine, a person’s risk of being hospitalized for COVID-19 was 93 percent lower than someone with similar characteristics but who had only received two vaccines. The results of this booster vaccine trial are similar to the results of another previous study that did not control for pre-existing conditions.
The study reports that its booster effectiveness was consistent across demographics, including those over 70 and under.
“These results convincingly demonstrate that the third dose of the vaccine, one week after the third dose, is highly effective against severe COVID-19-related outcomes in different age groups and population subgroups,” senior author Professor Ran Balicer from the Clalit Research Institute said in a statement. said.
The most important question that the study could not answer is whether the third dose is more permanent than the first two doses, whose effectiveness is known to decrease after six months.
The article acknowledges that while rich countries provide boosters to their own people, the uncontrolled spread of COVID-19 elsewhere raises the odds for even worse variants to emerge, but does not examine this issue. On the other hand, it is proving that if vaccines are distributed widely and quickly enough, they can control Delta-related deaths and hospitalizations.
The publication also overlaps with the evidence that mRNA vaccines are five times more protective than previous COVID-19 infection. . .
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