Incidence of Severe Respiratory Syncytial Virus Infections in Preterm Brazilian Children

"At Enrollment and Termination Visits all subjects will have phlebotomy performed for RSV antibody levels (3 mL of blood).~Subjects diagnosed with an LRTI during the study will have a nasopharyngeal lavage (NPL) for viral diagnosis. Phlebotomy for antibody levels will be performed if the current episode represents the first LRTI since study enrollment."

Subjects enrolled in one study site (located in Porto Alegre city) will perform Lung Function Analysis. First measurement will be performed up to Visit 6 and repeated at Termination Visit. Measurements collected in the first analysis will include respiratory compliance and resistance by passive deflation pressure - volume curve, lung volumes by gas dilution method (washout with SF6), lung clearance index with SF6, and maximal flows (rapid thoracic compression from raised volumes).