Anti-Covid vaccine: a fourth dose less effective against Omicron, according to an Israeli study

Should a fourth dose or not be faced with the Omicron variant? According to a preliminary Israeli study – the results of which are partial – this additional injection would raise the antibodies to even higher levels than the third dose, but would not be sufficient to prevent infections against this variant.

“We now know that the level of antibodies needed to protect and not be infected by Omicron is probably too high for a Covid-19 vaccine, even if it is a good vaccine”, the infectious disease researchers added.

This study was conducted by a team from Sheba Hospital, near Tel Aviv, which 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.

One week after the start of this clinical trial, which is to extend over six months, “antibodies (of the participants, Editor’s note) were multiplied by five, indicating that the vaccine works and offers protection against serious complications”, the hospital had told the press.

The fact remains that this Monday, three weeks after the start of clinical trials, Professor Gili Regev-Yochay, behind this study, specified that if the administration of these fourth doses indeed allows “to increase the level of antibodies”, she does“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” pointed out 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 launched a vast vaccination campaign in December 2020 which made it possible to offer three doses to almost half of the population. of 9.2 million inhabitants.

While Israel has experienced 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 at five days.