Fourth Pfizer Shot Boosts Protection From Covid, Study Shows

(Bloomberg) -- A fourth dose of Pfizer Inc.'s Covid-19 vaccine improves protection against infection and severe illness, according to an Israeli study. 

The findings, published Wednesday in the New England Journal of Medicine, were based on data from 1.2 million people ages 60 years and older. About half of the participants had a fourth jab, while the rest had only the third. 

The rate of severe illness among those who received a fourth dose was about three times lower than those who had received only a third dose, and the protection didn't decline throughout the eight-week study period. 

In addition, people with only three shots reported double the number of infections as those with the additional booster. However, protection against infection faded over the course of the study.  

Israel began offering a fourth dose of vaccine at the beginning of January as the omicron variant spread rapidly and evidence showed waning protection after three shots. Israel initially offered the additional booster to older and higher risk people before making it more widely available.

Since the start of the pandemic, some 3.9 million cases of coronavirus -- including more than 9,300 new cases on Tuesday -- have been confirmed in Israel, a country of 9 million people. The country has reported more than 10,500 deaths from Covid-19. 

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