The human metapneumovirus (hMPV), described for the first time in 2001, belongs to the Paramyxoviridae family, Pneumovinae subfamily, Pneumovirus genus.  Similarly to the influenza virus or the human respiratory syncytial virus (hRSV), it causes respiratory tract diseases, though with a milder course.  The hMPV is responsible for 7-8% of viral diseases of the respiratory tract among children and 2-3% among adults [1], attacking ciliated epithelial cells of the respiratory tract.  A disease caused by the human metapneumovirus has influenza-like symptoms (rhinitis, cough, fever).  The virus is widespread on all continents, and the highest frequency of its occurrence in observed in winter and spring.  It is characterised by droplet infection [2].  More severe symptoms, including serious infections of the lower respiratory tract, are found mainly with children and infants under the age of five [1][2], with elderly people above the age of sixty and with persons having a reduced immunity level [2]. 
As the American Lung Association and the latest reviews on the subject report, no medicine inhibiting or preventing infections caused by the hMPV has been approved for use hitherto [1,2,3,4,5].  Till 2012, only ribavirin ((1-β-D-ribofuranosyl-1,2,4-triazole-3-carboxamide)—a nucleoside being a guanosine analogue—exhibiting a broad range of actions against various viruses (RNA, DNA) of the respiratory tract [2,4,5], and immunoglobulins [2,5] were used for treatment of very severe acute infections caused by the hMPV among patients with lung transplants.  However, they were used only in critical cases, because of their undesirable effects and potential teratogenic activity [2,4]. 
Till now, a method for inhibition of hMPV replication by using peptides was disclosed, the peptides exhibiting a strong affinity to viral fusion protein F, thus blocking the lifecycle of the human metapneumovirus already at the stage of its fusion to host cells (Patent Application No.  US20040229219A1, Method of inhibiting human metapneumovirus and human coronavirus in the prevention and treatment of severe acute respiratory syndrome (SARS), 2004).  Other patent documents relate to prevention and inhibition of the hMPV by using proper antibodies or recombined human metapneumoviruses (application as vaccines).