‘Very Real Fourth Wave’ Presses FDA to Fully Approve Covid Shots

A surge in Covid-19 cases across the U.S. brought on by the fast-spreading delta variant is increasing pressure on U.S. drug regulators to fully approve Pfizer Inc.’s vaccine, the first one to apply for full licensure in the U.S.

Full approval could help the Biden administration ramp back up its immunization drive and reassure vaccine holdouts that the shots are safe. It could also make it easier for more schools and workplaces to put immunization mandates in place.

Meanwhile, breakthrough cases that penetrate the shot’s defenses are being monitored by health officials. While the Pfizer-BioNTech SE messenger RNA-based vaccine, ...