Almost a month after the Sheba Medical Center launch a landmark study to test the efficacy of a fourth vaccine against COVID-19, the hospital revealed in Press conference that this booster was only partially effective in protecting against infection by the Omicron variant.
A fourth injection of the COVID-19 vaccine raises antibodies to even higher levels than the third injection, but it is not enough to prevent Omicron infections, according to the preliminary study, the first of its kind, which is being developed in Israel, of which there are primary results, not yet published.
The Israel’s Sheba Medical Center administered second booster vaccinations in a trial among its staff and is studying the effect of the Pfizer booster in 154 people after two weeks and the Moderna booster in 120 people after the same time, As reported Gili Regev Yochay, director of that health center. These were compared to a control group that did not receive the fourth injection.
Those in the Moderna group had previously received three injections of the Pfizer vaccine, according to a statement from hospital authorities. “The vaccines led to an increase in the amount of antibodies even a little higher than what we had after the third dose,” Regev-Yochay explained. “However, this probably won’t be enough for Omicron,” told reporters in the preliminary presentation of the information.
Sheba’s trial programme, which began in December with injections given to 150 medical staff, is many times smaller than normal drug trials, typically involving thousands of volunteers whose results are tracked for months. But it is also the only known study of the effects of a fourth dose.
The findings, which the hospital says are the first of their kind in the world, are preliminary and have not yet been published.
“We already know that the level of antibodies needed to protect and not get infected with Omicron is probably too high for the vaccine, even if it is a good vaccine,” the specialist continued.
Israel was the fastest country to roll out initial COVID-19 vaccines a year ago and last month began offering a fourth vaccine, or a second booster, to the most vulnerable and high-risk groups.
Vaccines against COVID-19 were developed to target a certain genetic sequence of the spike protein of the virus that sticks to receptors on the surface of human cells. But nevertheless, experts say the spike protein of the Omicron variant is different in key places, making it difficult for the immune system to recognize the virus. “The conclusion is that the vaccine is excellent against the Alpha and Delta (variants), but for Omicron it is not good enough,” Regev-Yochay said.
Despite the limited success of a fourth injection, Israel’s decision to administer the dose to immunocompromised people could have a small advantage,” according to Regev-Yochay’s opinion. However, in the face of journalistic injunctions, it did not recommend extending this offer to the entire population. “If someone is at personal risk then it’s better to vaccinate now, if not then maybe it’s better to wait,” he said.
Simultaneously with the launch of this preliminary study, the Israeli Prime Minister, Naftali Bennett, Citing these findings, it stated “a fourth dose of the COVID-19 vaccine increases antibodies five-fold a week after the injection is given.”
Israel has played a leading role in studying the effects of COVID-19 vaccines, as the fastest country to roll out two-dose inoculations to a wide population a year ago and one of the first to give third shots as boosters.
Now administer fourth doses of the vaccine Pfizer-BioNTech to people over 60 years of age, health workers and immunocompromised patients.
More than four million people out of Israel’s population of 9.4 million have received three injections of the coronavirus vaccine.