Satisfaction with preliminary results of an Israeli study that examined the effect of the fourth vaccine.
The study conducted at the Ichilov Hospital in Tel Aviv shows that the additional dose of vaccine significantly increased the protection against infection, including in the Omicron strain.
According to Dr. Esti Sage, the lead researcher, "the risk of contracting the virus, 7 days or more after receiving the fourth dose, is twice as small."
However, it is important to add that it is not possible to determine with certainty which of the subjects was infected with the micron and which was not, due to the fact that no genetic sequencing was performed. It is assumed that due to the spread of the omicron at a time when those vaccinated with a fourth vaccine (early January) were sampled, most of the infected were infected with a variant that had already become dominant at this stage in the infections. In addition, these are only preliminary findings and Ichilov will continue to update regularly.
The study included 6,863 Ichilov workers who were vaccinated in the third dose during the months of August-December 2021 and had not previously been infected with the corona virus. Of these, 1,316 employees (19%) were vaccinated in the fourth dose as of January 3 ,22. During this period 608 workers were found to be positive for the corona virus, with 42 of them being found to be positive 7 days or more after receiving the fourth dose. Analysis of these data reveals a risk ratio of 0.52, which means twice the risk of contracting the virus seven days after receiving the fourth dose. The study's editors, Dr. Avishai Spitzer, Prof. Ronen Ben-Ami and Prof. Eli Schafercher, added a warning that "due to the short follow-up period, these results should be interpreted with caution.
The results of the study in Ichilov stand in contrast to the results of a similar study conducted at Sheba Hospital in Tel Hashomer and recently published.
The study in Sheba showed that the effectiveness of the vaccine against the omicron strain is low.
The leader of the research in Sheba, Prof. Gili Regev-Yohai, said when the preliminary data was revealed that the fourth dose increased the amount of antibodies fivefold, but "this protection is only partially effective against the omicron strain."
Even in light of these data, Prof. Regev-Yohai said that in her opinion "the decision to give a fourth vaccine to people aged 60 and over was a good one."
Participated in the preparation of the article: Dan Lavie
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