Robert Dawkins, a social justice activist, took one look at the numbers in Charlotte, N.C. — black residents make up about 22 percent of the state’s population but account for 39 percent of its positive cases — and knew the coronavirus would land hard in African-American communities. Ordinarily, he would knock on doors and go to churches to assess the damage and brainstorm solutions, but like other activists, he was forced to mobilize from home.

“We need to get to our people to get an idea of what the long-term repercussions are for an already fragile community,” said Mr. Dawkins, the political director of Action NC. “We are used to walking the streets and going to Wednesday Bible study and meeting people where they are. So now, we are quickly sending emails and calling and texting to check on people.”

Movements are made up of big policy ideas and small acts. Across the country, individuals are making direct pleas for the common cause of slowing the outbreak’s spread. In Chicago, Mayor Lori Lightfoot took matters into her own hands, driving around the city and breaking up crowds last week. The coroner in Albany, Ga., has visited the homes of people who died of Covid-19, making sure the surviving relatives are wearing masks and social distancing.

“I am trying to sound the alarm because I see the devastation in the black community,” Michael Fowler, the coroner of Dougherty County, said hours after the Georgia county’s 91st Covid-19 death. “I am trying to do my part. Preachers, a judge, a church choir member, all walks of life are dying. My job is to pronounce death, but I believe in trying to save lives.”

The disparity is the result of intersecting threats. African-Americans disproportionately belong to the part of the “essential” work force without insurance, and working from home is often not an option. That means more exposure to the virus, both in transit and in the workplace, and no way to access affordable health care. For many, the line from day-to-day living to Covid-19 patient is alarmingly short.

Weeks ago, public health departments began releasing the number of Covid-19 cases by race. Though the numbers were limited, it was enough to signal a brewing crisis within black communities. First, Milwaukee. Then Chicago and Detroit.