As China experiences a rise in respiratory infections this winter, one little-known virus has gotten a lot of attention – and some people may worry whether the rise in cases could be felt more broadly around the world.

Cases of human metapneumovirus (HMPV) and other seasonal viruses are on the rise across the northern hemisphere in early 2025, according to the World Health Organization. While news reports and social media videos have caused concern about a potential HMPV outbreak in China,

The CDC’s actions come in response to China's government-run media confirming that positivity rates of HMPV hare rising in children under the age of 14, despite respiratory illnesses being down overall since last year.