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About Human Metapneumovirus (hMPV)

Human metapneumovirus (hMPV) is a respiratory virus that was first described in 2001, when it was isolated from the respiratory tract of children in the Netherlands.1 hMPV is a member of the paramyxovirus family, along with respiratory syncytial virus (RSV). Broader use of molecular diagnostic testing has increased identification and awareness of hMPV as an important cause of upper and lower respiratory infection.2 In fact, hMPV represents one of the leading causes of acute respiratory tract infections in children, immune-compromised patients and the elderly and is considered a primary cause of death in infants under five years of age.1 Several studies have shown that hMPV is prevalent worldwide, affecting up to 86% of the global population of infants under five years old.1 This virus represents a significant economic burden on health care systems worldwide.3 In the United States alone, approximately 20,000 hospitalizations are registered every year due to hMPV.3 Further, approximately 1 million outpatient clinic visits and 263,000 emergency department visits may be associated with hMPV infection annually among U.S. children less than 5 years of age.4

Symptoms associated with hMPV are mainly respiratory problems ranging from coughing, wheezing, and fever to more severe complications, such as bronchiolitis and pneumonia. hMPV mainly infects the lower respiratory tract and in the most severe cases mechanical ventilation may be required.1 The most severe symptoms associated with hMPV infections are often reported in infants less than one year old, but are highly prevalent during early childhood up to five years old.1 High-risk factors in infants include asthma, preterm birth, and either previous or co-infections with other respiratory pathogens, such as Mycoplasma pneumoniae, RSV, and SARS-CoV-2.5-8 Like influenza and RSV, hMPV begins circulating among the general population during winter and lasts until the end of spring in the U.S.9

Currently there is no vaccine or specific antiviral treatment available for hMPV, thereby creating a significant unmet medical need.

86%

Several studies have shown that hMPV is prevalent worldwide, affecting up to 86% of the global population of infants under five years old.

hospital icon representing  clinic and emergency visits associated with hMPV infections
1 Million

Approximately 1 million outpatient clinic visits and 263,000 emergency department visits may be associated with hMPV infection annually among U.S. children less than 5 years of age.

Enanta’s Approach to Treating hMPV

By leveraging our experience with other respiratory viruses, we have discovered a series of novel small molecular inhibitors of hMPV achieving half maximal effective concentration (EC50) at nanomolar levels in vitro. These compounds are currently under lead optimization, with the goal of identifying a potential drug candidate in the second half of 2022.


  1. Gálvez, Nicolás M S et al. “Host Components That Modulate the Disease Caused by hMPV.” Viruses vol. 13,3 519. 22 Mar. 2021, doi:10.3390/v13030519
  2. Centers for Disease Control and Prevention: The National Respiratory and Enteric Virus Surveillance System (NREVSS)
  3. Divarathna, Maduja V M et al. “A Review on Epidemiology and Impact of Human Metapneumovirus Infections in Children Using TIAB Search Strategy on PubMed and PubMed Central articles.” Reviews in medical virology vol. 30,1 (2020): e2090. doi:10.1002/rmv.2090
  4. Edwards, Kathryn M et al. “Burden of Human Metapneumovirus Infection in Young Children.” The New England Journal of Medicine vol. 368,7 (2013): 633-43. doi:10.1056/NEJMoa1204630Edwards, Kathryn M et al. “Burden of human metapneumovirus infection in young children.” The New England journal of medicine vol. 368,7 (2013): 633-43. doi:10.1056/NEJMoa1204630
  5. Anderson, Evan J et al. “Prevalence and Characteristics of Human Metapneumovirus Infection Among Hospitalized Children at High Risk for Severe Lower Respiratory Tract Infection.” Journal of the Pediatric Infectious Diseases Society vol. 1,3 (2012): 212-22. doi:10.1093/jpids/pis069
  6. Lin, Pen-Yi et al. “Human metapneumovirus and community-acquired pneumonia in children.” Chang Gung Medical Journal vol. 28,10 (2005): 683-8.
  7. Hashemi, Seyed-Ahmad et al. “Report of death in children with SARS-CoV-2 and human metapneumovirus (hMPV) coinfection: Is hMPV the trigger?” Journal of Medical Virology vol. 93,2 (2021): 579-581. doi: 10.1002/jmv.26401
  8. Hon, Kam L et al. “Megapneumonia Coinfection: pneumococcus, Mycoplasma pneumoniae, and Metapneumovirus” Case Reports in Medicine vol. 2012, 310104 (2012) doi: 10.1155/2012/310104
  9. Haynes, Amber K et al. “Human Metapneumovirus Circulation in the United States, 2008 to 2014.” Pediatrics vol. 137,5 (2016): e20152927. doi:10.1542/peds.2015-2927