- Estimate the incidence rate of hMPV infection detected by RT-PCR from frozen nasal wash aspirates in children at high risk for severe LRI disease (hospitalized at <2 years of age).

• A prospective, epdemiological study to estimate the incidence rate of hMPV infection as determined by RT-PCR from frozen nasal wash aspirates taken from children hospitalized with LRI who are at high risk for severe disease.
• No study drug will be administered for this study.

Inclusion Criteria:

• Be premature (less than 36 weeks gestation) and less than or equal to 12 months of age, and/or
• Be less than or equal to 24 months of age with CHD (other than uncomplicated small atrial or ventricular septal defects or patent ductus arteriosus) that is judged to be hemodynamically significant, and/or
• Be less than or equal to 24 months of age with CLD of prematurity (BPD) requiring medical intervention/management (i.e., supplemental oxygen, steroids, bronchodilators, or diuretics within the previous 6 months).
• Hospital admission diagnosis referable to an acute lower respiratory tract infection or cardio/respiratory illness with a presumed respiratory infection (e.g., bronchiolitis, bronchitis, or pneumonia or cardiac decompensation associated with respiratory infection); admission must occur between October 1 and June 30 for northern hemisphere sites, and between March 1 and November 30 for southern hemisphere sites.
• Study enrollment within 2 days after hospitalization.
• Admission from the community to the Pediatric ward, Neonatal Intensive Care Unit, or the Intensive Care Unit.
• Have written informed consent obtained from the parent or legal guardian prior to study entry.

Exclusion Criteria:

• Known HIV infection or a mother with known HIV infection.