JERUSALEM — Preliminary results from a small Israeli study examining the effects of a fourth coronavirus vaccine dose suggest that despite an increase in antibody levels, the additional dose a few months after a third shot may not do much more to prevent infection with the Omicron variant.
Prof. Gili RegevYochay, who is the director of the Infectious Disease Unit of Sheba Medical Center, and the leader in the research, cautioned that results have not been peer-reviewed. She said there was no evidence that there was any risk of getting a fourth dose and that she supports giving the shots to those who might be most affected.
She said the study’s initial results raised questions about giving the extra dose more broadly, including to generally healthy people in their early 60s. She suggested that it might be better to wait for a more recent vaccine to combat variants such as Omicron.
On Tuesday, Dr. Sharon Alroy-Preis, a senior official at Israel’s Health Ministry, told Kan public radio that the decision to offer a fourth dose to older and more vulnerable people had been correct, since they had produced higher levels of antibodies. Higher levels of antibodies would likely provide additional protection against serious illness.
Initial results of the study showed that antibodies were five times stronger after the fourth dose. Professor RegevYochay explained to reporters that after receiving a fourth dose from Pfizer-BioNTech vaccine for 154 hospital workers, the number of coronavirus-infected participants was only slightly lower that the number infected in a group that had not received a fifth shot. The raw data were not made public by the hospital.
The study adds to the debate about whether a fourth shot is necessary. Israel made the shots accessible to Israelis 60 years and older, as well as to those considered especially vulnerable before much data was available. The Health Ministry acknowledged the lack of a scientific basis, but stated that there was no time for further research and deliberation due to rising numbers of new cases.
Israeli data shows that booster shots can cause immunity to wear off after a few months. Officials said that the potential benefits of getting a fourth shot outweighed any risks.
Scientists are still unsure if fourth shots are necessary. Research shows that Covid vaccines protect against the worst outcomes, even the Omicron variant. Experts have stated that while boosters are generally recommended in many countries, a few month-long doses may not be an effective long-term strategy.
A fourth dose was administered to about half a billion Israelis.
Some Israeli professionals were adamant that the rush to give a fourth dose, which was not well-tested, was a source of contention.
A panel of experts recommended that it be administered to people 60 years and older, as well to people with weak immune systems. Prime Minister Naftali Bennett enthusiastically supported the idea. Experts deemed the idea premature due to a lack of information about Omicron or the effectiveness of a fourth dosage.
Israel’s Ministry of Health approved rolling out the fourth vaccine for those 60 and older in early January.
It was not immediately clear if the Sheba news would slow down the uptake of those who are eligible for a fourth dose.
Source: NY Times