section_path: Epidemiology
section_name: Epidemiology
paragraph_text: Epidemiology
  
  HMPV was responsible for 12% of cases of acute respiratory tract illness in otherwise-healthy children in a US outpatient clinic and 15% and 8% of cases (respectively) of community-acquired pneumonia requiring hospitalization in children under and over the age of 5 in the United States in 2010–2012. The virus is distributed worldwide and, in temperate regions, has a seasonal distribution generally following that of RSV and influenza viruses during late winter and spring. Serologic studies have shown that by the age of five, virtually all children worldwide have been exposed to the virus. Despite near universal infection during early life, reinfections are common in older children and adults.
  
  HMPV may cause mild upper respiratory tract infection (e.g., the common cold). However, premature infants, immunocompromised persons, and older adults >65 years are at risk for severe disease and hospitalization. In some studies of hospitalizations and emergency room visits, HMPV is nearly as common and severe as influenza in older adults. HMPV is associated with more severe disease in people with asthma and adults with chronic obstructive pulmonary disease (COPD). Numerous outbreaks of HMPV have been reported in long-term care facilities for children and adults, causing fatalities.
  
  HMPV was responsible for 12% of cases of acute respiratory tract illness in otherwise-healthy children in a US outpatient clinic and 15% and 8% of cases (respectively) of community-acquired pneumonia requiring hospitalization in children under and over the age of 5 in the United States in 2010–2012. The virus is distributed worldwide and, in temperate regions, has a seasonal distribution generally following that of RSV and influenza viruses during late winter and spring. Serologic studies have shown that by the age of five, virtually all children worldwide have been exposed to the virus. Despite near universal infection during early life, reinfections are common in older children and adults.
  
  HMPV may cause mild upper respiratory tract infection (e.g., the common cold). However, premature infants, immunocompromised persons, and older adults >65 years are at risk for severe disease and hospitalization. In some studies of hospitalizations and emergency room visits, HMPV is nearly as common and severe as influenza in older adults. HMPV is associated with more severe disease in people with asthma and adults with chronic obstructive pulmonary disease (COPD). Numerous outbreaks of HMPV have been reported in long-term care facilities for children and adults, causing fatalities.