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, said Monday the Sheba hospital, near Tel Aviv, which has started one of the first clinical trials on the subject.
This trial was started in late December, vaccinating 154 caregivers with a fourth Pfizer dose and 120 other volunteers with a fourth Moderna dose. A week after the start of the research, which should extend over six months, "the antibodies (of the participants, editor's note) were multiplied by five, which indicates that the vaccine works and offers protection against serious complications", had indicated the hospital to 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 “ only offers a partial defense against the virus.”
“The Pfizer and Moderna vaccines, which were more effective against the other variants, offer less protection against Omicron”, underlined this infectious disease specialist in a press release published by the large Sheba hospital.
537,000 Israelis received their fourth dose
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 launched a vast vaccination campaign in December 2020 which made it possible to offer three doses to almost half of the population. population of 9.2 million.
VIDEO: Israel releases 4th dose of Covid-19 vaccine
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.
A strategy based on reminders is not viable, say WHO and EMA
In mid-January, the World Health Organization (WHO) and the European Medicines Agency (EMA) considered that fighting the Covid-19 pandemic with booster doses of current vaccines was not a viable strategy. .
For the European health body, a strategy based on vaccine boosters administered every four months will end up potentially causing “immune response problems”, in addition to increasing the risk of fatigue for populations.
Read alsoVaccination: do you need a booster dose even if you have had Covid-19 after two doses?
The EMA, which believes that the spread of the Omicron variant will gradually transform the Covid into an endemic virus, like the influenza virus, proposes instead to start spacing the boosters at longer intervals and to administer them at the start of Winter.
