Pfizer reduces symptomatic covid-19 infection 0:52
(CNN) ––
Pfizer / BioNTech's covid-19 vaccine appears to reduce symptomatic coronavirus infections by more than 90% in the real world, researchers from Israel reported Sunday.
Although the findings are preliminary, they suggest that the vaccine continues to be remarkably effective in a mass vaccination campaign.
That is, outside the carefully controlled conditions of a clinical trial.
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The Clalit Research Institute, which is part of a large Israeli healthcare system, analyzed data on 1.2 million people, of whom about half had received the Pfizer / BioNTech vaccine.
The researchers compared the vaccinated patients with similar people who weren't.
Pfizer / BioNTech vaccine reduced the rate of symptomatic covid-19 by 94%
The rate of symptomatic COVID-19 decreased by 94% among those who received two doses of the vaccine, according to a Clalit press release.
Symptomatic covid-19 is understood as people who became infected with coronavirus and felt sick, that is, they presented symptoms.
Additionally, the rate of serious illnesses was reduced by 92%,
Full details of the study were not immediately available and the research has not yet been peer reviewed.
However, the findings are consistent with data from Pfizer's own vaccine clinical trial.
This study found that the vaccine conferred 95% protection against symptomatic COVID-19.
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"The claim is really important," says CNN Medical Analyst Dr. Leana Wen.
Wen is also an emergency physician and visiting professor at the George Washington University Milken Institute School of Public Health.
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"You want to make sure that the results of the study that we initially saw in tens of thousands of people are reflected when the population is in the millions," he said.
In the Pfizer clinical trial, researchers randomly assigned patients to receive the vaccine or a placebo.
Then, they looked at how many people got sick in each group and found that the vaccine dramatically reduced the disease.
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Dr. Eric Topol, executive vice president of the Scripps Research Institute, said this is another important aspect reflected in the Israel study.
“It is very significant that they tell us that vaccination, in the real world at scale, achieves a remarkable reduction in severe covid-19, hospitalizations and deaths.
Which fully validates the randomized trial on mRNA vaccines, "he added.
An observational study
The Pfizer study was a randomized controlled trial, the leading standard in clinical research.
The Israeli study, for its part, was observational.
Which means the researchers didn't randomly choose who got the vaccine and who didn't.
That can pose problems.
For example, people who choose to get vaccinated may also be more likely to take other steps to protect themselves.
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However, the researchers said they tried to account for those types of effects.
Additionally, observational studies are important because they can provide some information about how well vaccines protect people in real-world conditions.
One of those conditions includes the presence of new variants.
Something Wen says is another reason these findings could be important.
“As I understand it, most of the strains found in Israel at the moment are of the B.1.1.7 variant.
And so, seeing this level of effectiveness, even in a population that has such a high level of that B.1.1.
7 is very good news, ”Wen added.
The researchers have not directly addressed the variants in their findings so far.
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