“The trust issues are just tremendous in the Black community,” said Edith Perry, a member of the Maryland Community Research Advisory Board, which seeks to ensure that the benefits of health research encompass Black and Latino communities.

The solution, she said, is not just to employ the conventional strategy of meeting with Black church congregations, especially if the government and vaccine producers want to reach millennials.

“The pharmaceutical industry would have to convince some of the young people in Black Lives Matter to get on board,” Mrs. Perry said. “Throw up your hands and say: ‘I apologize. I know we did it wrong and I need your help to get it right.’ Because we need a vaccine and we need Black and Hispanic participation.”

The chatter at The Shop Spa, a large barbershop with a Black and Latino clientele in Hyattsville, Md., underscores the challenges. Mike Brown, the manager, whose staff members have been trained to talk up wellness with clients, referred to the notorious Tuskegee experiments, and said, “I hope they don’t sabotage us again.”