With the coronavirus reproduction rate on the rise in recent days, medical officials have raised concerns protection provided by the third booster shot is beginning to wear off.
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Health Ministry officials, however, have rejected the claims, saying they have seen no signs of such a phenomenon at this stage.
Researchers tracking the efficacy of the booster shot noted that a slight decline in the protection provided by the booster dose is to be expected. They further said immunity could be maintained in other components of the immune system.
Researchers at Sheba Medical Center at Tel Hashomer are embarking on a study on effective antigens, which also play a role in protection from the coronavirus.
A senior Health Ministry official said, "There are no signs of a reduction in the impact of the booster, and [saying] that [is the case] is unreasonable as it is too soon for it to impact the reproduction rate. Even when you look at the mix of confirmed cases, you see these [people] are [comprised of the] unvaccinated and those who did not receive the third dose."
Professor Gili Regev-Yochay, the director of Sheba Medical Center's Infectious Disease Epidemiology Unit, is leading the study on antigen levels. She said: "Even if there are one or three participants in our study in whom we identify a decrease in antigen levels, we still cannot draw conclusions. The data is still under examination, and I hope we will have more information soon.
"The decrease in antigen levels is expected with time, and it's really not concerning because we are looking not only at the antigens but other things as well, such as the significance of the antigens and their quality. Right now, the data is very reassuring and should not be a cause for concern."
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As for when Israelis might expect to receive a fourth dose of the vaccine, Regev-Yochay said, "It won't be [another] six months, but longer. If it's 10 months after the booster, a year or two years, I still can't say."
Professor Dror Meborach, the head of Hadassah Ein Kerem's coronavirus unit, added: "There is no evidence of a decline in the booster's defense levels. On the contrary, we saw memory B cells that developed after vaccination with the booster. These are cells that create a lot of antibodies when they come in contact with the virus, and I, therefore, trust that the [efficacy of] the booster has not declined. I expect the booster vaccine to prove effective for longer than we think." He said the reason for the current outbreak "is the same reason this pandemic is taking place, which is that there are local outbreaks, which are right now often mediated through children. I hope Ben-Gurion Airport won't [result in] another outbreak due to the easing of restriction. The big question is whether the reproduction rate of 1.02 will continue to increase to 1.1-1.2 and then we will have the outbreak of a fifth wave."
Meanwhile, another Israeli study has found that newborns are best protected from the coronavirus when their mothers are vaccinated between Weeks 27 and 31 of their pregnancies.
According to the study, newborn babies whose mothers are inoculated at this stage in their pregnancy receive a higher level of antibodies than those born to women who were inoculated later on in their pregnancies, Haaretz reported.
The findings of the study by researchers from Hadassah University Medical Center and the Hebrew University's Faculty of Medicine, both in Jerusalem, were published in the European Journal of Clinical Microbiology and Infection earlier this month.
Dr. Amihai Rottenstreich, who along with Dr. Shay Porat and Professor Dana Wolf led the study, said, "We estimate that the placenta is able to filter and select only the most efficient antibodies for neutralizing the virus," Haaretz reported.
He further explained that "vaccinating pregnant women causes the antibodies … to be passed through the placenta to the fetus, thereby providing protection to newborns."
According to Rottenstreich, this is important because COVID results in more serious illness among newborns than older children, and "newborns can be another source for spreading the disease."
The research team is currently embarking on another study examining the impact of vaccination timing throughout the entire pregnancy among 400 women.
"Perhaps we should examine a recommendation unvaccinated women receive the first dose early in the pregnancy and the second one between Weeks 27 and 31 of pregnancy," Rottenstreich said.
The coronavirus vaccine has yet to be approved for children between the ages of six months and four years, although clinical studies on this age group are currently underway. Israel recently approved kids' sized doses of Pfizer's coronavirus vaccine for children aged 5 to 11. Thousands of such pediatric doses arrived at Ben-Gurion Airport Saturday.
In an interview with Kan Radio last week, coronavirus chief Professor Salman Zarka said the path to Israel providing Israeli patients with Pfizer's antiviral COVID pill would be a long one. He said, "The drug company still needs to submit materials to the US Food and Drug Administration and receive authorization, but we have already bought doses of the medicine anyway."
Commenting on the waning fourth wave, Zarka said the Health Ministry was closely monitoring new variants of the virus around the world. "It will be difficult to prevent a new variant from entering Israel, but we really want to identify it early, and that is why we have our finger on the pulse."
i24NEWS contributed to this report.
