The Centers for Disease Control and Prevention published its most complete national picture of mpox in more than a year last Thursday, and the numbers point travelers toward a different set of precautions than many have assumed.
The new analysis in the agency's Morbidity and Mortality Weekly Report counted 5,322 confirmed and probable cases across 2024 and 2025. Detections of travel-associated cases increased between the two years, and genomic and epidemiologic data showed evidence of 21 separate importations of the virus into the country. Further importations were observed in 2026 and are expected to continue.
What has changed for anyone boarding a plane is the agency's own posture. The CDC discontinued aircraft contact investigations for all mpox clades and subclades in 2025, a decision explained in a separate April report on aircraft contact tracing that examined what happened when infected passengers flew.
That earlier investigation followed 60 aircraft contacts of three men who traveled on five commercial flights while infectious with clade I virus, the strain that has driven international concern since 2024. One contact developed fatigue, body aches, and a skin lesion afterward and tested negative. No secondary cases were identified. The authors concluded that the risk of clade I transmission during commercial air travel "appears to be low," consistent with earlier findings for clade II.
The Cabin Was Never Where the Risk Concentrated
The reason is mechanical rather than reassuring rhetoric. Mpox spreads mainly through close, sustained physical contact with lesions, scabs, or contaminated bedding and clothing, and most often through sexual contact. The kind of contact that produces secondary cases rarely occurs between strangers seated near each other for a few hours.
An earlier and much larger investigation reached the same conclusion for the 2022 outbreak strain, finding no secondary cases among 1,538 people who had contact with 113 infected travelers across 221 flights. That finding led the agency to stop routine clade II aircraft investigations back in February 2023, and the newer clade I analysis extended the same reasoning to the remaining clades.
The practical translation for a family planning international travel is that seat assignment is not the variable worth worrying about. Vaccination status, destination, and the nature of contact at that destination are.
Importations Are Rising Even as Total Cases Hold Steady
The topline national figures are close to flat. There were 2,803 cases in 2024 and 2,519 in 2025. The overwhelming majority were clade II, the strain that has circulated domestically since 2022, with about 97.5 percent of sequenced samples descending from the 2022 outbreak lineage.
Underneath that stability, two shifts stand out. Reported cases roughly doubled from 423 during September and October 2024 to 873 during the same two months in 2025, before falling to 448 during November and December and returning to background levels by the end of the year. And clade Ib detections rose from a single travel-related case in 2024 to 10 in 2025. Of those 11 cases, three patients were hospitalized and recovered without antiviral treatment, and no deaths were reported.
Federal counts have continued climbing since. The CDC's clade I situation summary reports more than 40 laboratory-confirmed clade I cases in the United States since November 2024, and assesses the risk posed by the clade I outbreak to most people in the country as low. No deaths have been reported among roughly 150 clade Ib cases identified in high-income countries.
Local transmission has occurred but has not taken hold. A domestic cluster of three cases in October 2025 was traced back to a travel-associated introduction and did not spread further. Sustained clade Ib transmission continues in several European countries, where about 89 percent of cases have occurred among men who have sex with men.
City-level surveillance shows the ongoing background. New York City has recorded 102 positive mpox tests since the start of 2026, including 14 in the month ending August 8, according to figures posted by NYC Health and current as of August 13.
Vaccination Status Separated Mild Illness from a Hospital Bed
The most consequential finding for individual readers concerns outcomes rather than counts. Among 860 patients with complete records, the odds of hospitalization were 9.73 times as high for unvaccinated patients as for those who completed the two-dose JYNNEOS series, after controlling for age group and HIV status. Patients living with HIV had 2.37 times the odds of hospitalization compared with those without.
Unvaccinated people accounted for 76.1 percent of cases where vaccination status was recorded. Overall, 9.5 percent of patients were hospitalized, compared with 2 percent among those known to be vaccinated. Deaths remained rare, with five in 2024 and one in 2025.
The CDC's conclusion is that persistent low-level transmission of the 2022 strain suggests "a likely transition toward endemic circulation," and the agency recommends that people at risk of exposure complete both doses. That recommendation now explicitly includes travelers heading to countries with ongoing clade I or clade II transmission.
Gaps in the Data That Deserve Attention
Both reports carry limitations that the agency states directly, and readers should weigh them.
The air travel analysis was small. Sixty contacts across five flights is a small base, and health departments managed to interview only 29 of them. The absence of detected transmission in a small sample is weaker evidence than its absence in a large one, though it points in the same direction as the much larger clade II investigation.
The hospitalization finding is also less precise than the headline number suggests. The 9.73 figure has a 95 percent confidence interval ranging from 2.93 to 60.65, which is wide enough that the true effect could be much smaller or much larger. The direction is clear; the magnitude is not.
The surveillance report relies on passive reporting, so mild infections that do not prompt a medical visit are not captured, and total infections are likely undercounted. Missing data were substantial, with vaccination status absent for 62 percent of cases and HIV status for 68 percent. Analyzing only complete records can introduce selection bias.
For households, the reasonable steps are unchanged and modest. Anyone at elevated risk who has not completed the two-dose series can ask a primary care provider, sexual health clinic, or local health department about JYNNEOS, and travelers to affected regions should raise it before departure. People with mpox are advised to delay travel until their illness has resolved. Anyone who develops an unexplained rash after travel or close contact should contact a clinician promptly, mention the exposure, and avoid close physical contact until evaluated. Rapidly worsening symptoms, difficulty breathing, or severe pain warrant urgent care. The agency's recommendations on treatment and vaccination remain the same regardless of clade.
The agency updates its monthly U.S. case data in the first week of every month.
Key Questions Answered
Can someone catch mpox from a passenger on their flight? Investigations to date have not identified any such case. Among 60 contacts of three infected clade I travelers on five flights, no secondary cases were found, and a larger clade II investigation of 1,538 contacts also found none.
Why did the CDC stop tracing airline contacts? Because repeated investigations found no evidence of onboard transmission. The agency discontinued aircraft contact investigations for all mpox clades and subclades in 2025.
Does that mean mpox is not a travel concern? No. Travel-associated introductions are rising, and the agency documented 21 importations across 2024 and 2025. The risk is tied to close contact at the destination rather than to the flight itself.
Who faces the greatest risk of severe illness? People who are unvaccinated and people living with HIV. Unvaccinated patients had 9.73 times the odds of hospitalization compared with fully vaccinated patients, though the confidence interval around that estimate is wide.
Should travelers get vaccinated before an international trip? The CDC recommends the two-dose JYNNEOS series for people at risk of exposure, including travelers to countries with ongoing clade I or clade II transmission. A clinician or local health department can advise on individual eligibility.
What symptoms should prompt a call to a clinician? An unexplained rash or lesions, particularly following travel or close physical contact, along with fever, swollen lymph nodes, body aches, or exhaustion. Mention any recent travel when seeking care.
How current are these numbers? The national surveillance figures cover cases through December 31, 2025, and are provisional. The count of more than 40 clade I cases reflects the agency's situation summary page as currently posted.
