The novel coronavirus outbreak is spreading to vulnerable, elderly residents, with scores of cases at facilities around the U.S., from Illinois to Oregon and Wyoming, following the deadly outbreak in a Seattle-area nursing home.

By Wednesday, 35 coronavirus deaths were tied to the Life Care Center of Kirkland, Wash., and at least 10 other elder-care facilities in the area have had cases as well. Residents of such facilities have also died in New Orleans and Kansas City, Kan. Overall the death count has hit 150 in the U.S., while more than 9,400 people have tested positive, according to a Johns Hopkins University tally.

Health officials and researchers say they expect to see more coronavirus cases in elder-care facilities, despite aggressive steps by the industry and federal nursing-home regulators to limit visitors and isolate residents to avoid transmission. The respiratory illness caused by the virus, Covid-19, is often much more serious in older people and those with underlying health conditions such as heart disease.

Among other challenges, nursing homes are currently struggling to secure enough protective equipment such as masks, while federal data show many have been cited for infection-control problems in the past.

Elder-living facilities are also at risk because residents live in tight proximity, with staff interacting closely with them. Covid-19 can spread with few noticeable symptoms, or early symptoms that can mimic other conditions, such as influenza. As a result, one case can quickly swell into a major outbreak.