WASHINGTON — Researchers say federal government data significantly understated the ravages of COVID-19 in nursing homes last year.

Official numbers from the Centers for Disease Control and Prevention are missing about 12% of COVID cases among nursing home residents and 14% of deaths. That’s according to new estimates published Thursday in the Journal of the American Medical Association, Network Open, by a Harvard researcher and her team.

It translates to thousands of missing data points, suggesting more than 118,300 nursing home residents died of COVID-19 last year, or about 30% of all coronavirus deaths nationally.

The researchers attributed the data holes to the federal Centers for Medicare and Medicaid Services not requiring nursing homes to report cases and deaths until May 2020, well into the pandemic. The new estimates rely on numbers from states that required fuller reporting.