The first major real-world study of the Pfizer / BioNTech vaccine to be independently analyzed shows that the injection is highly effective in preventing Covid-19, at a potentially remarkable time for countries desperate to end blockages and reopen economies.
Until now, most data on vaccines against coronavirus came under controlled conditions in clinical trials, leaving an element of uncertainty about how the results would translate in the real world.
Research in Israel – two months on one of the fastest launches in the world, providing a rich source of data – showed that two doses of Pfizer injection reduced symptomatic cases by 94% across all age groups and serious illnesses almost the same proportion.
The study of about 1.2 million people also showed that a single injection was 57% effective in protecting against symptomatic infections after two weeks, according to data published and reviewed in the New England Journal of Medicine on Wednesday.
The results of the study for the Clalit Research Institute were close to those of clinical trials last year, which found that two doses were found to be 95% effective.
“We were surprised because we expected that in the real world scenario, where the cold chain is not maintained perfectly and the population is older and sicker, you will not get results as good as in controlled clinical trials,” senior study author Ran Balicer he told Reuters. “But we did and the vaccine worked well in the real world.”
“We showed that the vaccine is so effective in very different subgroups, in young and old, with no comorbidities and few comorbidities,” he added.
The study also suggests that the vaccine, developed by the American pharmaceutical company Pfizer and BioNTech in Germany, is effective against the coronavirus variant first identified in the United Kingdom. The researchers said they could not provide a specific level of effectiveness, but the variant was the dominant version of the virus in Israel at the time of the study.
The research did not shed light on how the Pfizer injection will fare against another variant, now dominant in South Africa, which has been shown to reduce the effectiveness of other vaccines.
Of the nine million people in Israel, a nation with universal health, almost half have received the first dose and a third have received both doses since the launch on December 19.
This made the country a prime location for a real-world study of the vaccine’s ability to contain the pandemic, along with its advanced data resources.
The study examined about 600,000 people vaccinated against the same control group as non-vaccinated people. Researchers at the Harvard TH Chan School of Public Health, Harvard Medical School and Boston Children’s Hospital also collaborated.
“This is great news, confirming that the vaccine is about 90% effective in preventing documented infection of any degree of severity from seven days after the second dose,” said Peter English, British government consultant on disease control communicable diseases.
“Recently studied earlier articles from Israel were observational studies. He used an experimental design known as a case-control study … giving greater confidence that the differences between the groups are due to their vaccination status, and not to some other factor. “
The study published on Wednesday was the first review of a national Covid vaccination strategy to be peer-reviewed. It also offered a more detailed view of how the vaccine was doing at weekly intervals, while comparing people who received the vaccine to non-vaccinated individuals with similar medical histories, sex, age and geographic characteristics.
Other research centers in Israel, including the Weizmann Institute of Science and the Israel Institute of Technology, have shared several studies in recent weeks that show that the vaccine is effective.
At least three studies in Israel have also suggested that the vaccine may reduce transmission of the coronavirus, but the researchers cautioned that broader studies should be carried out to establish clear conclusions.