As China continues to monitor an increase in cases of human metapneumovirus (HMPV), here's what you need to know about the illness.

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.

While cases are climbing in China, the situation is very different from what it was when Covid-19 emerged five years ago, medical experts say. HMPV has circulated in humans for decades.

In China, reports of HMPV infections have indeed been rising in recent weeks in the more northerly regions. But so have reports of all the other respiratory pathogens including seasonal flu, rhinovirus and RSV.

Experts say the disease is likely not going to be the next pandemic and the worry is a result of heightened wariness for respiratory illness in a post-Covid world. HMPV is a respiratory virus that regularly circulates during cold and flu season.

The Chinese Centre for Disease Control and Prevention (CDC) says the increase includes cases of human metapneumovirus (hMPV), a virus that affects the respiratory system. Human metapneumovirus is common during colder months and can cause mild to moderate illness.