Epidemiology of respiratory syncytial virus in children in Cyprus during three consecutive winter seasons (2010-2013): age distribution, seasonality and association between prevalent genotypes and disease severity.

This study reports the epidemiology of respiratory syncytial virus (RSV) in hospitalized children in Cyprus over three successive seasons (2010-2013) and the association between prevalent genotypes and disease severity. RSV infections had a circulation pattern from December to March. Most RSV-positive children (83%) were aged <2 years. Genotyping of RSV isolates showed that during the first winter season of the study (2010-2011), the only RSV genotype circulating was GA2 (RSV-A), followed by genotype BA (RSV-B) in the next winter season with only few sporadic cases of GA2. During the last winter season of the study (2012-2013) the newly emerged RSV genotype ON1 (RSV-A) was virtually the only circulating genotype. Children infected with genotype ON1 suffered a significantly milder illness compared to infections with genotypes GA2 and BA with a higher percentage of BA-infected children requiring oxygen. Our findings are in contrast to the majority of published reports that suggest RSV-A causes more severe illness than RSV-B. Therefore, further investigation of the association between RSV genotypes and disease severity is required, as it might affect treatment strategies in the future.