1. Division of Pediatrics, School of Medicine Pontificia Universidad Católica de Chile Santiago Chile
2. Division of Pulmonary Medicine, Department of Pediatrics University of Pittsburgh School of Medicine Pittsburgh Pennsylvania USA
3. Department of Public Health, School of Medicine Pontificia Universidad Católica de Chile Santiago Chile
4. Department of Obstetrics, School of Medicine Pontificia Universidad Católica de Chile Santiago Chile
5. Instituto de Ciencias de la Salud Universidad de O'Higgins Rancagua Chile
6. Department of Pediatric Infectious Diseases, and Millennium Institute on Immunology and Immunotherapy, School of Medicine Pontificia Universidad Católica de Chile Santiago Chile