CDC Alerts on Mpox Prevention for Patients Heading to Areas With Clade I Outbreaks

The CDC issued a Health Alert Network (HAN) update on Monday, emphasizing vaccination and patient education for U.S. travelers visiting countries with clade I mpox outbreaks, particularly for people at risk for acquiring mpox from sexual exposure.

The update is in response to the latest outbreak of the clade I mpox virus in Central and Eastern Africa. Currently, countries with ongoing human-to-human mpox transmission include Burundi, Central African Republic, Democratic Republic of the Congo, Republic of the Congo, Rwanda, and Uganda.

Of note, clade II mpox continues to circulate in the U.S. but no cases of clade I mpox have been reported here and the risk of clade I mpox continues to remain low. However, two cases of the clade Ib variant were recently identified in Sweden and Thailand in people who had traveled to Africa; another clade Ib case was reported in India in a man who had traveled to the United Arab Emirates.

The CDC update emphasized that clinicians should recommend vaccination against mpox with the two-dose series of the modified vaccinia Ankara-Bavarian Nordic vaccine (Jynneos) to any adult if they are traveling to a country where clade I mpox is spreading between people, and they also anticipate any of the following during their trip:

• Sex with a new partner
• Sex at a commercial sex venue, like a sex club or bathhouse
• Sex in exchange for money, goods, drugs, or other trade
• Sex in association with a large public event, such as a rave, party, or festival

The mpox vaccine series should be started at least 6 weeks before travel begins because the second dose of the vaccine should be given 28 days after the first vaccine and it takes 14 days for immunity to peak. Two doses of the vaccine are most effective, but one dose has been shown to be 75% effective against clade IIb mpox.

Clinicians should continue to follow the CDC’s current vaccine recommendations for at-risk individuals to prevent clade II mpox infection because vaccination can also help protect against clade I mpox.

The agency also emphasized that clinicians should discuss mpox prevention and risk reduction strategies with all travelers to countries with ongoing human-to-human transmission of clade I mpox. Discussions should include patients’ sexual history and travel plans, education about sexual contact (regardless of sexual orientation or gender identity) and mpox exposure risk, and whether patients may be sexually active with new partners during travel.

Clinicians should provide detailed education to patients on activities that may increase risk for mpox exposure and how to reduce that risk. For example, people traveling to affected countries should avoid close contact with people who are sick with signs and symptoms of mpox, including skin or genital lesions. They should also avoid contact with potentially contaminated materials of people who may have mpox, such as clothing, bedding, toothbrushes, sex toys, or materials used in healthcare settings.

For patients who may be at risk of mpox exclusively from day-to-day household contact or patient care, clinicians should provide information about risk reduction strategies other than vaccination.

So far, the Democratic Republic of the Congo has reported more than 21,000 suspected clade I mpox cases during 2024, its largest annual number on record. As a result, the WHO declared a global public health emergency in August. A large proportion of clade Ib mpox cases among adults appear to have been spread through sexual contact, including in some countries where the virus is not normally found.

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