What is HMPV respiratory virus that is wreaking havoc in the US?

A new virus is picking up the steam. Should it be considered as a new threat? While the cases of COVID & RSV are falling, another respiratory virus called HMPV is spreading. In early March, around 20% of antigen tests & nearly 11% of PCR tests for HMPV were positive in the US. Cases of human metapneumovirus spiked this spring.