[1] Hosp Pediat David Bernardino, Luanda, Angola
[2] Univ Diego Portales, Santiago, Chile
[3] Inst Nacl Saude, Lisbon, Portugal
[4] Univ Helsinki, Cent Hosp, Dept Otorhinolaryngol, Helsinki, Finland
[5] Univ Helsinki, Cent Hosp, Hosp Children & Adolescents, Helsinki, Finland