Vaccinations

WASHINGTON — Federal officials and drugmakers, faced with a slower-than-expected rollout of the coronavirus vaccine, are racing to find ways to expand the supply, looking at lowering the required dosage and extracting more doses from the supplies they have.

Just weeks into the vaccine program, scientists at the National Institutes of Health and the drugmaker Moderna are analyzing data to see if they can double the supply of the company’s coronavirus vaccine by cutting doses in half. The study, though long planned, is increasingly urgent in the face of looming shortages as the country tries to fight off a surging pandemic.

In Florida, less than one-quarter of delivered coronavirus vaccines have been used, even as older people sat in lawn chairs all night waiting for their shots. In Puerto Rico, last week’s vaccine shipments did not arrive until the workers who would have administered them had left for the Christmas holiday. In California, doctors are worried about whether there will be enough hospital staff members to both administer vaccines and tend to the swelling number of Covid-19 patients.