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

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.

Cases of human metapneumovirus, or HMPV, a contagious virus that can lead to respiratory disease, is reportedly spiking in northern China. Infectious disease experts say risk to the U.S. is low.