Data showed 94% fewer symptomatic coronavirus cases and 92% fewer cases of serious illness among those vaccinated.
People get vaccinated at the Clalit vaccination center in Jerusalem, January 3, 2020.
(photo credit: MARC ISRAEL SELLEM/THE JERUSALEM POST)
The Pfizer vaccine not only prevents infection but also reduces the risk of contracting a serious case of COVID-19, new data released Sunday by Clalit Health Services shows.
The data, which was based on a study of 1,200,000 people – 600,000 who received the vaccine and 600,000 who did not – showed 94% fewer symptomatic coronavirus cases and 92% fewer cases of serious illness among those who were vaccinated.
The study showed that the vaccine was equally as effective among people 70 and older as it was among younger participants. Among those who were vaccinated, some 170,000 people were over the age of 60.
It was also found that the Pfizer vaccine is most effective one week after the second dose, mirroring the company’s own clinical studies.
In a preliminary examination of the results, after 14 days or more had passed since people received their second dose, the vaccines were found to have even higher efficacy for the prevention of symptomatic and severe disease, said Prof. Ran Balicer, Clalit’s chief of innovation.
The control group was carefully adjusted to ensure that it paralleled those who were vaccinated, including based on level of risk for developing a serious infection, health status, age and more, according to Clalit.
Events such as quarantine and changing vaccination guidelines were also accounted for.
These results are the first in what is expected to be a series of studies released by the Clalit Research Institute to evaluate the effectiveness of the vaccine on various and diverse groups, Balicer said.
“For weeks, we have developed tools and methodologies to deal with the many biases that characterize this type of research in real-world data,” he said, adding that Clalit worked with colleagues at Harvard University to perform a series of tests to validate the results.
Last week, Maccabi Healthcare Services shared preliminary data on its own vaccination campaign, highlighting that fewer than 0.1% of individuals who received their second dose of the Pfizer vaccine contracted COVID-19.
Maccabi showed vaccine effectiveness in Israel to be at 93%. Pfizer’s Phase III clinical trial showed it to be 95% effective.
Clalit said it has given out more than 3.2 million first and second vaccine doses.
In total, Israel has administered more than 6.3 million vaccine doses.