U.S. health regulators are seeking additional coronavirus booster shot data from Moderna Inc., as the Biden administration expects to begin a widespread booster campaign this month with only the Pfizer Inc.-BioNTech vaccine, people familiar with the matter say. Moderna announced Friday that it had “completed” its submission of data to the Food and Drug Administration for authorization of boosters. Moderna also submitted booster-shot data to the European Medicines Agency for a conditional marketing approval.