Epidemiological and genetic characteristics of human metapneumovirus in pediatric patients across six consecutive seasons in Beijing, China.

•There was a higher incidence of human metapneumovirus (hMPV) infection in inpatients than outpatients.•A biennial alternating pattern of hMPV infection, fluctuating with hMPV activity, was observed.•There was a clear-cut demarcation between the end of one season and the start of the next.•hMPV activity increased with the apparent decline in influenza activity.