An elderly woman receives a booster shot of her vaccination against the coronavirus disease (COVID-19) at an assisted living facility, in Netanya, Israel January 19, 2021. REUTERS/Ronen Zvulun

A fourth COVID-19 shot reduces the risk of death by 72 percent among those with an average age of 80, according to an Israeli study conducted among nursing homes residents.

The study, published in the JAMA Internal Medicine journal and conducted by Tel Aviv University and Ben Gurion University of the Negev, along with the Israeli Ministry of Health, found that a fourth dose of the Pfizer vaccine is effective in protecting elderly people living in long-term care facilities from the Omicron COVID-19 variant.

“This is a groundbreaking and innovative study based on a database of the elderly population in care facilities,” said Prof. Khitam Muhsen of the School of Public Health at Tel Aviv University. “We monitored the infections, hospitalizations and mortality rates throughout the Omicron wave, and found that the members of the group that received the fourth vaccine were infected at a rate that was 34 percent less than the control group; were hospitalized for mild-to-moderate illness 64 percent less, and for severe illness 67 percent less than the control group; and had a mortality rate that was 72 percent less than the group vaccinated with only the first three doses.”

The study included about 40,000 Israelis 60 or older, and was supervised by the Health Ministry’s program to oversee the control of COVID-19 in geriatric facilities. Israeli researchers monitored 24,088 residents at about 1,000 nursing care facilities across the country who received a fourth vaccine dose — the second booster shot — and 19,687 residents who were vaccinated with the first three doses but who chose not to get another booster.

Muhsen explained that previous studies have been conducted among the general population, and among relatively younger populations with an average age of around 72, versus an average age of 80 in the current research.

“We assume that the fourth dose of the vaccine boosted the level of neutralizing antibodies, which conferred cross-protection against the Omicron variant,” Muhsen said. “Our study points to the significant benefit of administering the fourth dose of the vaccine, and confirms that the policy adopted by the State of Israel was the correct one.”

“The decision to vaccinate at-risk populations with the fourth dose was a wise choice that saved a lot of human lives,” she concluded.