Kaiser Permanente has pledged $1 million toward efforts to prevent and treat COVID-19 cases among the nation's homeless population.

The Oakland, Calif.-based health system on Monday partnered with the advocacy group National Health Care for the Homeless Council to fund at least four housing activist groups in California, Seattle and Portland, Ore.

Those areas account for nearly half of all coronavirus cases in the U.S. and have some of the largest homeless populations in the country.

Kaiser's pledge will help homeless shelters expand their capacity and give organizations resources such as cleaning supplies and protective equipment for outreach workers.

"We must do our part to care for our members as well as our most vulnerable populations," said Dr. Bechara Choucair, chief health officer with Kaiser Permanente, in a statement. "Given the elevated risk faced by people living on the streets or in shelters at this time, we are making it a priority to support outreach, prevention, and treatment for this community."

Reports indicate the number of coronavirus cases in the U.S. had reached more than 3,600 as of Monday.

Public health officials have urged people to avoid mass gatherings and remain in their homes if possible as a means of reducing their risk of infection. But housing advocates have expressed concerns that homeless individuals are especially vulnerable to the virus since they can't self-isolate indoors.

A 2019 analysis conducted by the U.S. Department of Housing and Urban Development found the number of people who were homeless increased by nearly 3% in 2019 compared with 2018, which was mostly driven by an 8.5% increase on the West Coast. The total number of homeless individuals in California alone is estimated at more than 151,000, according to the agency.

If coronavirus infections become widespread among the homeless, that could spark a significant mortality increase. Homeless individuals have a higher likelihood of having underlying medical conditions that can put them at higher risk of developing more severe outcomes from the virus.

The U.S. House of Representatives passed an emergency relief package Saturday that would provide paid sick leave, unemployment insurance and food assistance to those infected. The legislation did not include assistance for homeless shelters.