RESUMEN
BACKGROUND: Respiratory syncytial virus (RSV) infections are the leading cause of hospitalization in young children. We assessed the epidemiology, severity, clinical characteristics, molecular profile and genetic factors of RSV infections compared to acute respiratory illness (ARI) caused by other respiratory viruses. METHODS: Prospective cohort study was conducted from 2017 to 2018 with children under 2 years old hospitalized with ARI. Detection of respiratory viruses was carried out using RT-PCR. RSVs were genotyped via nucleotide sequencing, and host interleukin 28B (IL28B) single nucleotide polymorphisms (SNPs) were determined using SNP TaqMan® Genotyping Assays. RESULTS: A total of 468 children were included; 288 (61.5%) had an infection by a single virus: 202 (70.1%) cases by RSV followed by rhinovirus 36 (12.5%) and influenza 16 (5.6%). Of the RSV cases, 36% were genotyped with a higher prevalence of RSV B (62.1%). The RSV group presented median age of 2.7 months (1.6-6.8), higher frequency in: intensive care unit admission (p = 0.004), mechanical ventilation use (p = 0.018), wheezing (p < 0.001), antimicrobial use (p < 0.001) and low oxygen saturation (p < 0.001). Prematurity (27.2%) was the most frequent comorbidity. RSV patients without comorbidities demonstrated a higher frequency in the combination of IL28B rs12979860 CT/IL28B rs8099917 TG and IL28B rs12979860 TT/IL28B rs8099917 TT genotypes. Viral coinfection was detected in 27 (5.7%) children, with the most frequent being RSV and rhinovirus (14.2%). CONCLUSIONS: This study highlighted the burden of RSV infection in children under 2 years of age, without comorbidities, with a higher need for pediatric ICU admission. Some IL28B allele combinations had a significant association with RSV frequency of infections.