Johnson & Johnson said Tuesday an additional dose of its COVID-19 vaccine boosted its efficacy to 94% in mild to severe infections, up from 74% for just one shot. The J&J shot also has longer-lasting efficacy than the mRNA vaccines authorized in the U.S., according to a recent study. J&J says their data still needs to be reviewed by the FDA before any recommendations can be made about a second dose. Meanwhile, the World Health Organization once again warned against wealthy nations offering booster shots for the general population, with so many countries still lacking basic access to the vaccine.