In recent weeks, scenes of hospitals in China overrun with masked people have made their rounds on social media, sparking worries of another pandemic.

Beijing has since acknowledged a surge in cases of the flu-like human metapneumovirus (HMPV), especially among children, and it attributed this to a seasonal spike.

But HMPV is not like Covid-19, public health experts have said, noting that the virus has been around for decades, with almost every child being infected by their fifth birthday.

However, in some very young children and people with weakened immune systems, it can cause more serious illness. Here is what you need to know.