Who needs a fourth dose of the Corona vaccine?

Despite the disappointing results of the fourth dose of the Corona vaccine on long-term protection from infection, vaccines are still useful in protecting against severe symptoms and death, according to experts.

“Receiving the fourth dose will be important for vulnerable populations who need this additional protection,” said Gili Regev Yochai, an infectious disease specialist at Sheba Medical Center.

For those who are elderly or at high risk, and those with compromised immune systems, an additional dose may be needed to help protect against severe disease, says Dr. Yuchai. “In general, I would recommend receiving any possible protection,” she added.

And according to what was reported by the American “ NPR ” website, a preliminary study from Israel, published last week, indicated that most people do not need a fourth dose.

“Vulnerable groups are likely to need another booster,” said Yale University immunologist Akiko Iwasaki. He continued, “Their immune response is not as strong as a healthy young man.”

In the face of the epidemic, rich countries have resorted to additional booster doses to protect against infection with the Coronavirus, but studies have proven that the antibodies that rise after obtaining a new vaccine dose quickly decline after 3 months.

On Tuesday, Sweden began offering a fourth dose to people over 80 who live in nursing homes. Chile also provided a fourth dose to anyone over 55 who had received the third dose 5 months ago.

Also, Israel allowed a fourth dose of the COVID-19 vaccine for people over 60 and any adult with chronic health conditions or immunodeficiency.

During the 30-day Israeli study period, about 20 percent of the people who received the extra dose developed the highly infectious omicron variant, compared to about 25 percent of those who received only three doses. The fourth dose does not appear to activate the T cells that remain necessary to prevent future infections.

“Neither a third, nor a fourth, nor a fifth dose will stop the infection” in the long term, said Dr. Yuchai, the study's lead author.

Earlier this month, data from a study in this regard published by the Centers for Disease Control and Prevention in the United States, “CDC”, indicated that the effectiveness of booster doses during the stage of spread of the Omicron mutant decreased from 91 percent in the first two months after taking the dose. The third, to 78 percent in the fourth month approximately.

The data showed that the effectiveness of the booster dose against hospitalization (the patient had to go to a hospital for treatment from Corona) changed during the same period from 87 percent in the first two months to 66 percent by the fourth month, and only 37 percent after about five months.