Mass Covid-19 vaccination sites like this one in Glendale, Arizona, have helped increase vaccination rates, but some residents are having a hard time getting appointments at all. | Courtney Pedroza/Getty Images

Local health clinics and community groups are better than mass vaccination sites at reaching the most vulnerable people.

The good news is that the rate of Covid-19 vaccinations in the United States is increasing, while the rates of new infections, hospitalizations, and deaths are slowing. As of this week, more than 66 million doses have been administered to at least 42 million Americans, about 13 percent of the total population.

But the disease is still spreading, and there aren’t yet enough vaccine doses to meet demand. And many who need a vaccine the most are having the hardest time getting one.

From signing up for appointments to securing