WASHINGTON — Two of the Food and Drug Administration’s top vaccine regulators will leave the agency this fall, a development that could disrupt its work on deciding whether to recommend coronavirus vaccines for children under 12 and booster shots for the general population.

The daily average for hospitalized Covid-19 patients in the United States is now more than 100,000 over the last week. That average is higher than in any previous surge except last winter’s, before most Americans were eligible to get vaccinated.

The influx of patients is straining hospitals and pushing health care workers to the brink as deaths have risen to an average of more than 1,000 a day for the first time since March. The seven-day average of Covid hospitalizations peaked in mid-January with nearly 140,000 people hospitalized.