Long-term care facilities are a major contributor to COVID-19 deaths, accounting for up to 81% of the fatalities in at least two states. 

That’s according to a study published Friday in the Journal of the American Geriatrics Society using state data from the Kaiser Family Foundation, among other sources. While states differ in their definition of long-term care, reports generally included nursing homes, group homes and intermediate care facilities. Some included data from assisted living facilities.

By the end of May, 26 states had reported that long-term care deaths accounted for 50% or more of their total COVID-19 deaths. The highest rates were in Minnesota and Rhode Island at 81%, Connecticut at 71%, and New Hampshire at 70%, wrote first author Thomas T. Perls M.D., MPH, from the Boston University School of Medicine.

In other cases, death rates are most certainly undercounted, according to Perls and colleagues. New York state for example reported a death frequency of 21%. That total is unlikely considering that rates in neighboring states are up to four times higher, they wrote. The data did not include the number of patients transferred from hospitals to long-term care facilities under state orders. Furthermore, deaths were counted based on positive COVID-19 tests, which were largely unavailable to nursing facilities in March and April.

Along with undercounting, there was a significant delay in the receipt of death certificates made worse by overwhelmed funeral homes and morgues, the researchers reported. “The current reported total number of [long-term care] deaths in the U.S. must be severely underestimated,” they concluded.

Since May 6, U.S. nursing facilities have been required to report confirmed or probable COVID-19 cases to the Centers for Medicare and Medicaid Services. As of Thursday, there were 95,000 confirmed cases and 32,000 deaths reported by 88% of the nation’s nursing facilities.