Boost now? Boost later? Tricky calculation for a 4th coronavirus shot.

Even highly informed consumers of pandemic news may struggle to sift through the latest US government guidance and newest scientific studies. And even at this stage in the crisis, they may be unclear on what additional boosters can and can’t do. Public health officials who authorized a second booster shot last month for people 50 and older and for immunocompromised people 12 and older have insisted it’s a stopgap, aimed primarily at keeping the most vulnerable people out of the hospital or the cemetery. A second booster appears to add to protection against severe illness in people 60 and older but offers only a modest, temporary shield against infection.