Fourth booster dose of Covid-19 vaccine boosts antibodies to even higher levels than the third dose, but not sufficient to prevent infection by the Omicron variant, according to a preliminary study conducted in Israel.
The Israeli Sheba Medical Center administered second booster doses in a clinical trial to its staff members and is testing the effect of the booster dose of Pfizer's vaccine on 154 people after two weeks and the booster dose of Moderna on 120 people after one week, said Gili Reger Yohai , director of the Infectious Diseases Unit.
The vaccines caused an increase in the number of antibodies "even a little higher than we had after the third dose," Reger Yohai said.
"However, this is probably not sufficient for Omicron," she told reporters. "We know so far that the level of antibodies needed to protect and prevent infection from Omocron is probably too high for the vaccine, even if it is a good vaccine."
The findings, which the medical center said were the first of their kind in the world, are preliminary and have not yet been published.
Israel was the fastest country to begin initial vaccinations a year ago and last month began offering a fourth dose of vaccines, or a second booster, to the most vulnerable high-risk groups.
Meanwhile, the Ministry of Health announced today that it will shorten to five from seven days the mandatory quarantine period for those diagnosed positive for Covid-19, after an initial reduction last week, provided the sick are asymptomatic.
Until last week, the quarantine period was 10 days.
The latest decision, which will take effect Wednesday, brings Israel in line with U.S. recommendations.
The measure also requires sick people to take a negative antigen test at home before the isolation period ends, the ministry said.
Prime Minister Naftali Bennett said the increase in the number of cases due to the Omicron variant and the number of people in isolation has become a burden on the Israeli economy.
"This decision will allow us, on the one hand, to continue to ensure public health and, on the other hand, to guarantee the stability of the economy in this period, even though it is difficult, so that we can safely ride out this wave," Bennett said.
The Israeli government's pandemic response coordinator, Salman Zarqa, said the Health Ministry found that people are more contagious in the first three days after infection.
Source: Proto Thema
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