Transmission of clade 1 mpox virus during commercial air travel appears to be uncommon, according to a study published yesterday in Morbidity and Mortality Weekly Report from the US Centers for Disease Control and Prevention (CDC).
The analysis looked at data from five commercial flights taken by three men with active mpox symptoms to assess the risk of in-flight transmission. The three men were aged 20 to 40 years. The flights took place from November 2024 to January 2025.
Among 60 identified contacts, defined as nearby passengers and crew, one person reported symptoms of fatigue, body aches, and a skin lesion after the flight, but that person tested negative for mpox. No secondary cases were identified.
Vaccination reduces transmission, severity
Mpox is an infectious disease that causes painful rashes and blisters, as well as flu-like symptoms. It is caused by the mpox virus, which is divided into different genetic groups, or clades. The virus is most commonly spread through close, prolonged physical contact.
Clade 2 mpox began spreading globally in 2022, and roughly 37,500 cases have since been reported in the United States, where transmission is still occurring.
Previous contact tracing has indicated that the risk of clade 2 mpox transmission during commercial air travel is low. But prior data suggested that clade 1, which began circulating in central Africa in 2023 and has resulted in roughly 150 travel-associated cases outside of Africa, might be more transmissible. The current investigation did not find evidence supporting the spread of clade 1 in an airline setting.
Based on these results, the CDC discontinued routine aircraft contact tracing for all mpox clades and subclades in 2025. But public health officials continue to recommend that people with mpox avoid travel until they have fully recovered. Vaccination of at-risk groups remains an important tool for reducing transmission and disease severity, the authors said.