A fourth vaccine dose could soon be made available for over-18s in Israel to deal with rising cases of Omicron infections in the country.
The Israeli Ministry of Health vaccine advisory committee recommended the extra booster dose for all adults over 18 if their third shot was administered at least five months earlier.
The advice is based on preliminary data on the effectiveness of the fourth dose of Pfizer-BioNTech's Covid-19 vaccine collected in Israelis over 60.
The decision is awaiting approval by the head of the Ministry of Health.
Research involving more than 400,000 people who had received four doses reported half the infection rates compared with those given three shots.
Sheba Medical Centre
Severe disease was reported to be up to five times less common in those given a fourth shot of Pfizer, rather than in those with three.
Doctors, however, noted older patients given a fourth booster were more likely to be cautious and avoid risky exposure compared to others in the community.
“Overall, during the Omicron wave in Israel, people vaccinated with three doses have excellent protection against severe disease, compared with unvaccinated. However, the fourth dose provided additional protection,” said Prof Eyal Leshem, an infectious diseases specialist at Sheba Medical Centre.
“Based on that data, it seems plausible that people who suffer from risk factors for severe diseases, as is the case with many senior citizens and those who suffer from chronic illnesses, may have some added protection provided by a fourth dose.
“It is important to note that three doses of the vaccine provide excellent protection against severe disease for young and healthy people and the added value for a fourth dose is currently unknown and not expected to be substantial.”
A recent study of the effectiveness of a fourth Pfizer-BioNTech vaccine given to 154 frontline health workers at Sheba Medical Centre, the largest hospital in Israel, found it to be less effective against Omicron than previous variants.
Although a fourth shot did not provide optimal protection against Omicron, it did boost antibodies when compared to a third vaccine.
Latest data from the Ministry of Health shows 76,017 cases detected from 348,235 tests, which is a positivity rate of 21.83 per cent.
Sheba hospital currently has 192 inpatients being treated for Covid, 73 in a serious condition, eight of whom are children.
In a recent media briefing, Dr Anthony Fauci, director of the US National Institute of Allergy and Infectious Diseases and adviser to the White House, warned against repeated booster programmes when some countries were still facing shortages.
“We cannot have a virus circulating freely in one part of the world, as long as that happens you will get a virus that impacts all of us,” he said.
The World Health Organisation set a target of fully vaccinating 40 per cent of the population in every country by the end of 2021.
In Africa, only seven nations have hit that target — Seychelles, Mauritius, Morocco, Tunisia, Cabo Verde, Botswana and Rwanda.
Only 9 per cent of the continent has been fully vaccinated against Covid-19 to date.
“From a global perspective, use of multiple boosters in low-risk populations during a short period should be weighed against the global shortage of Covid vaccines,” Prof Leshem said.
“The global community should now focus on prioritising and delivering vaccines to vulnerable unvaccinated populations in third-world countries where vaccine coverage rates are still low.”
