A large proportion of people with monkeypox are living with HIV, according to recent reports. While anyone can get monkeypox through close physical contact, cases remain overwhelmingly concentrated among men who have sex with men.

The World Health Organization and the Centers for Disease Control and Prevention (CDC) both found that 41% of people with monkeypox are HIV positive. The rate is a bit lower in the United Kingdom, at 26%, but in the state of Georgia, 67% of cases are among people living with HIV. Among HIV-negative men with monkeypox, a majority are taking pre-exposure prophylaxis (PrEP).

The good news is that people with well-controlled HIV do not appear to have worse monkeypox outcomes. But this may not be true for those with untreated HIV and a low CD4 count. Prior reports from Nigeria showed that people with HIV had more severe illness and higher mortality.

The two-dose Jynneos monkeypox vaccine is safe for people with HIV, but the older ACAM2000 smallpox vaccine should not be used by people with a weakened immune system. In an effort to stretch the limited Jynneos supply, some jurisdictions are using a one-dose strategy or intradermal administration, which splits a single vial into five doses. While the vaccine provides good protection for people with HIV, experts advise that HIV-positive people—-especially those with a lower CD4 count—should be prioritized to receive the optimal number of doses using the most effective administration method.

People with HIV who contract monkeypox should continue their antiretroviral therapy, and those newly diagnosed with HIV and monkeypox at the same time should start as soon as possible. HIV-positive people and those on PrEP can take the antiviral medication TPOXX (tecovirimat) to treat monkeypox along with their antiretrovirals, according to recent CDC guidance.

“Although data are limited for monkeypox in patients with HIV, prompt diagnosis, treatment and prevention might reduce the risk for adverse outcomes and limit monkeypox spread,” the guidance states.