A new comprehensive Israeli study has found that a fourth COVID-19 vaccine dose triples the protection against severe illness in people aged 60 or above, compared to three-dose protection, the Israeli Health Ministry said.

On April 5, the ministry said that the study published in the New England Journal of Medicine was conducted by it along with three leading Israeli universities and the Sheba Medical Center, Israel's largest hospital, Xinhua news agency reported.

Using the ministry's database, the researchers extracted data on 1,252,331 persons aged 60 or above and eligible for a fourth dose.

It was conducted when the Omicron variant of SARS-CoV-2 was predominant, between January 10 and March 2.

Except for the three-fold lower severe illness rate among those vaccinated with the fourth dose, it was found that the protection did not decline throughout the study's eight-week period.

The rate of verified COVID cases among these people was twice as low as those who received the third dose, but protection against confirmed infection appeared short-lived, according to the study.