Medical Personnel

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.

Like many Black and rural Americans, Denese Rankin, a 55-year-old retired bookkeeper and receptionist in Castleberry, Ala., did not want the Covid-19 vaccine.

Ms. Rankin worried about side effects — she had seen stories on social media about people developing Bell’s palsy, for example, after they were vaccinated. She thought the vaccines had come about too quickly to be safe. And she worried that the vaccinations might turn out to be another example in the government’s long history of medical experimentation on Black people.