The first U.S. death this year due to a monkeypox infection has been confirmed in California in an individual who health authorities say was “severely immunocompromised.”

The Los Angeles Department of Public Health and the Centers for Disease Control and Prevention confirmed on Monday that a Los Angeles County resident died due to a monkeypox infection. The infected individual had been hospitalized.

“Public Health sends heartfelt condolences and wishes of healing to the family and friends mourning the loss of their loved one,” the city health department stated. “The resident was severely immunocompromised and had been hospitalized.”

No further information on the individual such as age, gender or ethnicity was shared by the department, which cited a need to protect “confidentiality and privacy.”

This is the first death confirmed to be caused by monkeypox. A Texas man, who was also described as being severely immunocompromised, died last month after being diagnosed with monkeypox, though the role that the infection played in his death is still being investigated.

Nearly 22,000 monkeypox cases have been confirmed in the U.S. California has the most confirmed cases among U.S. states so far, with 4,300 cases.

Monkeypox infections are rarely fatal, with most cases resolving within two to four weeks. According to the World Health Organization, the disease has a fatality rate of around 3 to 6 percent. However, immunocompromised individuals are more likely to experience severe illness when infected, as is the case in many viral infections such as COVID-19.

Symptoms of a monkeypox infection include flu-like signs such as fever, muscle aches and fatigue, which are shortly after followed by the painful skin rash associated with the virus. Contact with the fluid from the characteristic rash is the main pathway through which the virus is spread.

While there are no drugs specifically meant to treat monkeypox, smallpox vaccines and treatments such as Jynneos and TPOXX have been deployed to prevent infections and potentially prevent severe illness. Monkeypox and smallpox belong to the same family of viruses, and previous studies have indicated that smallpox treatments are also effective against monkeypox, though clinical data is limited.