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,

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.

Plenty of viruses are having their strongest season for years. But experts have urged calm about HMPV, which is not a new disease — even if you've never heard about it.

China’s winter illness season is less severe compared to the year before, according to data from its health authority. But the proliferation of a long-standing though little-known pathogen called human metapneumovirus (hMPV) has been raising alarm both at home and in other countries.

Rising cases of common respiratory illnesses in China and elsewhere around the Northern Hemisphere are within the range expected for winter, WHO says.

A rise in cases of human metapneumovirus in China is stoking fears of a new health crisis, though authorities and experts say prospects for a sequel to the COVID-19 pandemic are remote. The big picture: HMPV is similar to respiratory syncytial virus,

WHO said, ‘Human metapneumovirus, hMPV is not a new virus’, adding that it generally spreads in winter and spring.