The pictures emerging are arresting: a hospital waiting room in Beijing, full of masked patients apparently attached to drips; crowds of mask-wearing commuters making their way through the city. If it all seems unnervingly familiar,

Authorities in China said they are monitoring cases of human metapneumovirus, or HMPV, after a reported increase inside the country, according to Reuters. Although cases are increasing at a rapid rate,

Cases are climbing in China, but the situation is very different from when COVID-19 emerged five years ago, medical experts say. HMPV is common and decades old.