The administration of a fourth dose of the Pfizer or Moderna vaccines makes it possible to multiply the antibodies, but proves to be “less” effective in combating the Omicron variant of the coronavirus, an Israeli hospital said on Monday having started one of the first clinical trials on the subject.
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A team from Sheba Hospital, near Tel Aviv, initiated a clinical trial at the end of December, vaccinating 154 caregivers with a fourth Pfizer dose and 120 other volunteers with a fourth Moderna dose.
A week after the start of this clinical trial, which should extend over six months, “the antibodies (of the participants, editor’s note) have increased fivefold, which indicates that the vaccine works and offers protection against serious complications”, the hospital had told the press.
On Monday, however, three weeks after the start of clinical trials, Professor Gili Regev-Yochay, who is leading this study, clarified that if the administration of these fourth doses does indeed “increase the level of antibodies”, it does not “offers only partial defense against the virus”.
“The Pfizer and Moderna vaccines, which were more effective against the other variants, offer less protection against Omicron,” said this infectious disease specialist in a press release published by the large Sheba hospital.
In an attempt to mitigate the effects of a new wave of contamination linked to the Omicron variant, the Israeli government recently gave the green light to administering a fourth dose to people who are older or considered to be at risk of developing symptoms. serious.
More than 537,000 Israelis have received a fourth dose of the vaccine, according to the latest data from the Ministry of Health in this country, which in December 2020 launched a vast vaccination campaign which made it possible to offer three doses to almost half of the population. population of 9.2 million.
While Israel has seen contamination records in recent days, the maximum treatment capacity of hospitals has not been reached and the number of recent deaths remains low.
In this context, and given the pressures on the economy linked to the spread of the Omicron variant, which generally causes less severe symptoms, the government decided on Monday to reduce the duration of the quarantine of people positive for Covid-19 from seven to five days.