(January 16, 2022 / JNS) Health experts have expressed reservations about the safety and effectiveness of a fourth dose of the COVID vaccine, even as half a million Israelis have taken the additional shot.
“I don’t know if there’s a need for a fourth booster,” Pfizer CEO Albert Bourla said in a recent interview with US media. “It’s something that needs to be tested…I don’t think we should do anything that isn’t necessary.”
Last month, Israel became the first country in the world to administer fourth injections to immunocompromised people, the elderly and healthcare workers. Last week, Greece approved a fourth vaccine for those most at risk. Chile has also announced that it will offer citizens a fourth dose of the vaccine, also starting with those who are most at risk of infection or developing serious illness, but these injections are not expected to begin until February and will not be administered only after six months. from the previous move. Brazil has also approved a fourth vaccine, but only for the immunocompromised.
Will the second reminder be a lifeline or a handicap?
The answer, it seems, is still unknown.
A representative of the European Medicines Agency expressed reservations last week, warning that too frequent vaccination against COVID-19 could harm the immune response.
Recalls “may be done once or even twice, but it’s not something that we can think of as having to be repeated constantly,” said Marco Cavaleri, head of biological health threats strategy and vaccines at the EMA, during a press briefing. “Although the use of additional boosters may be part of contingency plans, repeated vaccinations at short intervals would not represent a sustainable long-term strategy.”
The World Health Organization has also issued statements against a widespread fourth dose, although the organization has acknowledged the need for a third injection in some cases.
“With the short- to medium-term supply of available vaccines, the need for equitable access to vaccines in all countries to achieve global public health goals, programmatic considerations, including vaccine demand and evolving of the virus, a vaccination strategy based on repeated booster doses of the vaccine’s original composition are unlikely to be appropriate or sustainable,” the WHO said on January 11, adding that “although some countries may recommend booster doses of the vaccine, the immediate priority for the world is to accelerate access to primary vaccination, in particular for groups most at risk of developing serious disease.
Israeli researchers said they were not convinced that four doses would overload the immune system, although they admitted that a COVID policy based almost entirely on injections was proving ineffective.
Israel has diagnosed more than 40,000 new cases a day in the past few days, and experts estimate the actual number of sick people to be two to three times higher.
“You can get two boosters, but basing your strategy on injections every four months doesn’t make sense,” said Professor Cyrille Cohen, head of Bar-Ilan University’s immunology laboratory. “We have a problem, and we have to recognize that there is a problem and we have to solve it.
“We have to come to understand that vaccines cannot prevent contamination,” he continued. “Repeated injections defeat the purpose of the vaccine, which is to stop a serious infection. You cannot take a new dose every time you have a new variant.
Moreover, Israel’s decision to administer a fourth dose was “based on expert opinion and not on hard data, because there was no hard data”, Professor Eyal Leshem explained, director of the Center for Travel Medicine and Tropical Diseases at Sheba Medical Center.
His hospital has been at the forefront of evaluating the effectiveness — and decline — of Pfizer’s coronavirus vaccine.
The hospital is currently in the middle of a clinical trial evaluating the safety and efficacy of a fourth dose of the Pfizer and Moderna vaccines in about 300 healthcare workers. Last week, Sheba released preliminary results showing that the extra boost is safe in the short term and leads to a five-fold increase in antibodies.
However, the trial’s lead researcher, Dr Gili Regev-Yochay, said army radio that “the amount of antibodies returns to the level it was after the third vaccine, no more. That’s good, but it’s not what you expect from a booster.
Leshem also said the EMA’s concerns were “theoretical” and “not based on any information.” He said there are several vaccines for which people get three or more doses, including the polio vaccine which requires six doses over a lifetime. He admitted, however, that no vaccine requires so many doses in such a short time.
“We don’t have enough data to say whether the decision to give a reminder provided enhanced protection against serious illness or hospitalization,” Leshem said.
To assess the real benefit of the booster, he said, scientists will need to compare all people at risk of serious illness who received a fourth dose to those who might have had but did not, which can only be done effectively in several weeks.
In the meantime, “I don’t think it will harm anyone,” he said.
For now, Israel has been content to administer the vaccine only to those most at risk of infection. Last Monday, a Health Ministry advisory committee on vaccines did not approve extending the campaign to the entire population.
At the same time, research shows that while vaccine efficacy will be reduced against symptomatic disease caused by the Omicron variant, protection against severe disease is more likely to be preserved, according to the WHO.
Over 60% of Israelis have received two doses of the coronavirus vaccine, around 80% of the eligible population have received two doses and a booster. Nearly 25 percent of children aged 5 to 11 have also been bitten since Israel launched its childhood vaccination campaign in November.
Vaccination, Leshem and Cohen said, is likely part of the reason why, as severe cases increase, they do so at a much slower rate than in any previous wave, although it is understood that the Omicron variant in general is less virulent than previous variants.
Additionally, data provided by the Ministry of Health shows that there is an almost 10-fold reduction in serious illness in people over 60 who are fully vaccinated compared to those who are not.
Leshem said that as more vaccinated Israelis catch Omicron, combined immunity may prove more effective and lessen the need for any future boosters.
“The virus will continue to evolve,” Cohen said. “There will always be variations. Let’s review our strategy.