Pfizer and BioNTech’s Covid-19 vaccine perform just as well in the real world as in the clinical trial that led to their use, a large study done in Israel concluded.
The study, published Wednesday in the New England Journal of Medicine, is the largest to date to evaluate the effectiveness of the vaccine, comparing all diseases, serious illnesses and hospitalizations, as well as deaths between 600,000 pairs of vaccinated and non-vaccinated .
That a vaccine will perform just as well in the real world as in the highly controlled environment of a clinical trial is not self-evident, said senior author Ran Balicer, director of the Clalit Research Institute of Israel.
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“The vaccine has lived up to its promise. And it was a surprise to see that a vaccine could perform just as well in a real environment as in the very controlled environment of a clinical trial, where cold chain is perfect and the people are careful. elected, ”said Balicer, who also chairs an expert panel advising the Israeli government on the pandemic.
But he warned that although the vaccine performed very well – it is 94% protective against symptomatic Covid, in all age groups, even older adults – some people who were fully vaccinated had serious illnesses and that some died. During the study period, nine people who were fully vaccinated against Covid-19 died, compared with 32 people who had not yet been vaccinated.
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“These vaccines are not a force field around you that denies the chance that you will have a disease or that you will have a serious illness,” Balicer said, while two doses of the vaccine provide substantial protection against severe Covid infection and death. , “There is residual risk.”
‘And therefore I think that constant precautions, especially among the populations at risk … at a time when the distribution of the community is clear and large, as is the case in Israel, would be the wisest thing to do. do, even for those who have been fully vaccinated, “he said.
Kathleen Neuzil, director of the Center for Vaccine Development at the University of Maryland School of Medicine, finds the results of the study encouraging.
“It was a well-conducted study and the findings support the impact of the vaccine on multiple important outcomes – any infection, symptomatic infection, hospitalizations and deaths,” she said. “The speed with which we are impacting after the launch of the SARS-CoV-2 vaccines … offers hope that with sufficient vaccine provision we can get this pandemic under control.”
The authors of the study, from various institutions in Israel, as well as Harvard School of Public Health and Boston Children’s Hospital, reported some data that is likely to play into the ongoing debate as to whether it is safe to take the second dose of Pfizer vaccine. delayed. to give a first dose to more people faster.
The Pfizer vaccine is a two-dose vaccine intended for 21 days apart. Health authorities in Britain have already decided to postpone the administration of the second dose, and some experts in the United States insist that this country follow suit. But so far, the Food and Drug Administration has resisted requests to change the dose schedule for the virus.
Almost everyone in Israel who received the vaccine received their second dose on time, so the study could not answer the question of how well the protection provided by the first dose of vaccine would last if not given at the right time.
However, the analysis showed that from day 14 after the first shot – the point at which protection appears to take effect – until day 20, the day before the second dose, there was moderate protection against any infection, but better protection against serious diseases. .
During that narrow period of time, the protection against documented Covid infection after one dose was 46% – less than the FDA’s prescribed 50% reduction in effectiveness. But for symptomatic infection, hospitalization, and serious illness, the protection for that period was 57%, 74%, and 62%, respectively.
The authors estimated that one dose of vaccine was 72% protective against Covid’s death in the seven-day period, but because the number of deaths was low, it is difficult to draw firm conclusions.
The study also found that the vaccine works well in people with significant health problems – another real test that vaccines do not always succeed.
Noa Dagan, an author of the Clalit Research Institute, said that the vaccine for people with one or two health conditions that increase the risk of serious Covid disease works just as well as for people who are healthy.
Even in people with three or more health conditions, vaccine protection appears to be strong, with about 89% efficacy, she said.
As Covid vaccines are used more widely, there will be a multitude of studies to see how well the vaccines work and whether some in some sections of the population work better than others. Such data is much needed as the world tries to figure out how to use the best vaccines that are barely available for months or more.
“I think the results are useful in that we can use large observation data sets to fill gaps in our understanding, mainly by enabling finer breakdown of ages, comorbidity and time since vaccination, as has been done here,” Natalie said. Dean, biostatistician at the University of Florida.