Human metapneumovirus (HMPV) causes illness in both children and adults. Like other viruses, infection produces incomplete immunity and re-infection can occur at all ages. The aim of this research was to identify the incidence and clinical impact of HMPV infection over four consecutive winters in adults in both an inpatient and outpatient setting.

The authors used serum and respiratory secretions over a period of four winters from four prospective cohorts. Nasopharyngeal swab specimens were …