According to a new Israeli study that was peer-reviewed, the fourth shot of the COVID-19 vaccine increases the antibody levels for about 13 weeks in patients.
The study further disclosed that the protection the 4th shot against infection appears to fade in about 15 weeks.
It should be noted that the first generation of the Pfizer vaccine were the focus of the study and not the recent ones, which have been updated for combating the Omicron variant and are currently circulating in Israel.
Furthermore, it is still unclear as to what kind of protection antibody levels can offer against serious illness due to COVID-19 because this metric was not considered in the study.
This means that it is quite possible that the vaccine could provide protection against severe illness for a period of more than three months during which the antibody levels in the body are high.
Nonetheless, the authors of the study who work at the Sheba Medical Center, said that healthcare providers should consider this research for wisely devising the timings of the booster campaigns.
Timing of boosters
The authors said that healthcare providers should only give boosters when there is a possibility of high infection because the protection that the boosters provide against infection reach their peak relatively quickly.
Otherwise, they said that the boosters should be given when patients are faced with circumstances that increase their risk of infection.
One of the lead authors of the study and Sheba’s director of infectious diseases, Prof. Gili Regev-Yochay, said that since protection wanes after four months, the booster timing should be wisely planned by health systems and individuals.
The lead author said that they should not just consider surges in infection, but also seasons of higher risk, upcoming travel and events and personal medical conditions.
The Sheba researchers carried out the study, along with Columbia University’s Dr. Michal Canetti and experts from the Health Ministry.
The New England Journal of Medicine published the study, which was based on 6,000 employees of Sheba and volunteers.
Some COVID-19 experts have also taken note of the study and said that even though the booster only increase the antibody levels for a short period of time, it still carries a lot of value.
Prof. Michael Edelstein, an epidemiologist at the Bar Ilan University, who was not part of the study, said that the timeframe might be a short one, but it might be enough to provide protection to those who are vulnerable during times of high risk, such as peaks of transmission.
According to the study, the fourth shot does not increase the antibody level by the same number as the third shot.
The researchers did add that they could not say anything about severe illness because none of the participants in the research had any.
Edelstein stated that it showed that the fourth shot had more transient benefits as opposed to previous ones.
He added that more research was required to determine how severe illness is affected by the fourth shot.