Study: Fourth vaccine dose improves protection by a factor of about 3

 https://www.israelnationalnews.com/news/325294

A new study that was published in the New England Journal of Medicine examined the effectiveness of the fourth dose based on data of over one million people aged 60 or older who were eligible for the vaccine, in the period between January 10 and March 2.

The study found that the rate of severe disease among people who received the fourth dose was lower by a factor of about three compared to people who only received three vaccine doses, and that this protection did not wane throughout the study period.

The rate of confirmed infection in those receiving the fourth dose was lower by a factor of about two compared to people who only received three doses, but this protection waned throughout the eight-week study period.