Posts have flooded social media warning that a new pandemic could be starting in China. Here's why scientists think those fears might be overblown.

An outbreak of human metapneumovirus in China has raised concerns of another widespread respiratory illness. HMPV has likely been around for centuries, and it has likely infected most people once in their lifetime.

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.