Major Israel study finds Pfizer vaccine cuts infection rate

Pfizer vaccination / Photo: Company website

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The Clalit Health Fund compared 200,000 Israelis over 60 who received the vaccine with 200,000 who did not.

Israel's largest health maintenance organization (HMO) the Clalit Health Fund has published the results of the first major research on the effects of Pfizer's Covid-19 vaccine. Clalit examined 200,000 people aged 60 and over who have received the vaccination and needed a Covid-19 test, and compared them with 200,000 who have not been vaccinated and also needed to be tested, and examined the percentage who tested positive for Covid-19, among each group.

Between the fifth and twelfth days after the vaccination, there was still no difference in the number of positive Covid-19 tests between the two groups. But from 14 days onwards after the vaccination, there was a significant fall of 33% in the percentage of people testing positive for the virus who had had the vaccination, compared with those who had not.

Bearing in mind that the vaccinated group still need to have their second Pfizer vaccination, in order to build full immunity, the results that Clalit found were in line with expectations. In its trial Pfizer had found the effects of the first vaccination kicking in after 11 days. The similarity between Clalit's research in Israel, and Pfizer's trial results, has strengthened the feeling that the lower percentage of people testing positive was from the vaccine and not other variables.

Clalit Research Institute director Prof. Ran Balicer explained that while Pfizer's research was based on people who felt Covid-19 symptoms, Clalit's research included people from both groups who came to be tested because they felt symptoms but also others who had come into contact with somebody diagnosed with Covid-19.

Clalit's research also matches a smaller project conducted by Prof. Gili Regev, Director of Infectious Disease Epidemiology Unit at Sheba Medical Center at Tel Hashomer near Tel Aviv. She examined 200 people who had received their first vaccination and found that after a week only 1% had developed enough antibodies to provide immunity but that number had risen to 50% after two weeks.

Prof. Balicer said, "We are waiting to cross reference the data we are monitoring over time, in order to confirm these findings. But the results match in terms of the timeline and the trend that we have seen in the controlled research of the vaccine producers."

Meanwhile the virus has been worsening in Israel. For the second day running, the Ministry of Health has reported more than 9,000 new cases of Covid-19, although the number of serious cases has stabilized at just over 1,000.