An Israeli research team found that the 4th dose of the COVID-19 vaccine was only effective in preventing infection with the Omicron mutation in the elderly in 4 to 8 weeks.
Based on data from the Israeli Ministry of Health, Israel's Weizmann Institute and other researchers analyzed the risk of infection and severe progression of 1.25 million elderly people over the age of 60 who had not received the second booster shot and had not been infected with COVID-19 before January 3 of this year. .
As a result of the analysis, the rate of infection with COVID-19 among those who received the booster shot twice was only half of those who received the booster shot twice by 4 weeks after the inoculation.
However, this infection prevention effect decreased after 8 weeks, and there was no difference between the two groups.
The effect of preventing severe progression was maintained longer than this.
The rate of severe progression of COVID-19 in the third inoculation was 3.5 times that of the fourth inoculation based on the fourth week after the second booster shot inoculation, and the difference was 4.3 times in the sixth week after the inoculation.