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So far, most of the data on SARS-CoV-2 vaccines have been evaluated under controlled conditions in clinical trials, leaving some questions about how the results would translate in the real world, under real conditions, which implies a greater variety of people and logistical challenges behaviors, such as maintaining the cold chain.
Held in Israel, two months after the country began one of the most ambitious vaccination plans in the world, This study is a data source and reveals that two doses of the Pfizer vaccine reduced symptomatic cases of Covid-19 by 94 percent in all age groups..
The research, based on data from nearly 1.2 million people treated by one of Israel’s largest healthcare organizations (Clalit Health Services), between December 20, 2020 and February 1, 2021, It also showed that a single injection was 57 percent effective in protecting against symptomatic infections after two weeks..
“We were surprised because we expected that in the real world scenario, where the cold chain is not perfectly maintained and the population is older and sicker, we would not get as good results as in controlled clinical trials.”Ran Balicer told Reuters. “But we did it and the vaccine worked well in the real world.”.
In fact, the results of this study were similar to those of vaccine clinical trials, which indicated that two doses were 95 percent effective.
“We show that the vaccine is effective in very different subgroups, in young and old, in those without comorbidities and in those with few comorbidities.”he added.
Effective vaccine against variants?
Israeli research also suggests that the vaccine, developed by the American pharmaceutical company Pfizer and the German company BioNTech, is effective against the variant first identified in the UK. The study authors say they cannot indicate a specific level of effectiveness, but the British variant was dominant in Israel at the time of the research.
As for the new variant identified in South Africa, the researchers say there is not yet enough data to demonstrate the effectiveness of the vaccine.
But since the British coronavirus variant was dominant in the country at the time the study was conducted, the research team finds the results more interesting.
According to the data analyzed, almost 600,000 people who received the vaccine were “closely associated” with about 600,000 others who did not receive the injection, and they had very similar characteristics in terms of sex, age, but also comorbidities and location. When comparing the two groups, The authors concluded that vaccination reduced symptomatic cases of Covid-19 by 94%, severe cases of the disease by 92%, and hospitalizations by 87%.
These fees apply to protection obtained at least seven days after taking the second dose.
“The recent studies also carried out in Israel were observational studies. An experimental design known as a case-control study was used, which gives greater confidence that the differences between the groups are due to their vaccination status and not to some other factor”.
Half of the vaccinated population
Of the nine million citizens of Israel, a nation with a universal healthcare system, nearly half have already received the first dose and a third have received two doses of the vaccine since the vaccination plan was launched on December 19. These figures have made Israel the ideal place to test the true capacity of the vaccine and, consequently, its ability to contain the pandemic.
The study, conducted in collaboration with researchers from Harvard’s TH Chan School of Public Health, Harvard Medical School, and Boston Children’s Hospital, looked at about 600,000 vaccinated people and another 600,000 in the unvaccinated control group, and also revealed “a very significant effect” even “before the second dose,” with an efficacy of 57 percent for Covid-19 cases with symptoms and 62 percent for severe cases..
As France Press Noam Barda, one of the study’s two lead authors, noted, The vaccine was also effective in preventing Covid-19 deaths after the first dose, but its low number in this study makes this result less reliable.
Efficacy was relatively constant for all age groups, “including people older than 70 years.”Ben Reis said. On the other hand, “We have evidence that for people with many (previous) illnesses, the vaccine works a little less.”.
What’s more, the study reports a 92 percent effectiveness against the very possibility of being infected (and not just developing symptoms). This is a crucial fact because, if confirmed, it may indicate that vaccinated people can no longer transmit the virus.. But this result must be viewed with caution, as the authors themselves admit.
“It is encouraging, but at the same time this study cannot guarantee that we will detect all asymptomatic infections.”Noam Barda warned.
For that, it would require all participants to be tested very regularly, proactively, which was not the case here. However, another Clalit study in this direction is already underway.
Other Israeli research centers, including the Weizmann Institute of Science and the Israel Institute of Technology, have already shared several studies in recent weeks that also show that the vaccine is effective. At least three Israeli investigations have also suggested that the vaccine may reduce the transmission of SARS-CoV-2, but the researchers cautioned that larger studies are needed to draw clearer conclusions.
The latest data from the Weizmann Institute also shows a sharp drop in the circulation of the disease since the population began to be vaccinated, which allowed the rules of the third national closure to be relaxed and some sectors of the economy reopened. While some sites are open to everyone, others are only accessible to people with the “green pass,” meaning they received the second dose of the vaccine at least a week ago or recovered from the Covid-19 infection.
