Although mpox cases related to the 2022 global outbreak were diagnosed in people who had traveled aboard, the virus now is spreading continuously in the United States.

Persistent, low levels of mpox “suggest a likely transition toward endemic circulation,” according to a report in the Centers for Disease Control and Prevention’s (CDC’s) flagship publication, Morbidity and Mortality Weekly Report. The paper also quantifies the risk of hospitalization in unvaccinated mpox patients.

Mpox spreads through close contact, such as cuddling, kissing, or sex. Mpox can spread among household contacts, either from skin-to-skin contact or by sharing towels or bedding. In the current outbreak in Guinea-Bissau, half of cases are in children.

In the United States, mpox is most common among men who have sex with men. The CDC recommends that people at risk for mpox, including those traveling to countries with outbreaks of the virus, receive two doses of the Jynneos vaccine.

Unvaccinated at much higher risk of hospitalization

In 2024 and 2025, according to the report, 76% of mpox cases in the United States were in unvaccinated people, who were nearly 10 times as likely to be hospitalized with the virus as those who received both vaccine doses.

Before 2022, US mpox cases were related to foreign travel or infections from small animals imported from abroad. There are two types of mpox, clade 1 and clade 2. The CDC confirmed about 30,000 clade 2b mpox cases in the United States in 2022.

The global outbreak of clade 2b mpox that began in 2022 has infected 100,000 people in 122 total countries, including 115 countries in which mpox was not previously reported.