Johnson & Johnson says its Covid booster shot prevents severe infection

The results come as many developed nations turn to booster shots to address waning protection from some vaccines and the rise of the more infectious delta variant

A booster dose of Johnson & Johnson’s Covid-19 vaccine provided 100% protection against severe disease when given two months after the first inoculation, according to widely anticipated data that suggests it increases the potency of the one-time shot. 
 

The booster was 94% effective at preventing symptomatic Covid infections in the U.S. portion of the Phase III trial, and 75% effective overall when it was given 56 days after the initial dose, the company said in a statement. A second study found the additional shot spurred a 12-fold increase in production of antibodies against Covid when it was given six months