Background Respiratory Syncytial virus (RSV) infection can cause severe morbidity leading to hospitalization and admission to paediatric intensive care unit (ICU). Limited epidemiological data exist about RSV as cause of lower respiratory tract infection (LRTI) requiring hospitalization in Central and Eastern Europe (CEE).

Methods This is a prospective cross-sectional observational multi-country epidemiological study. Children younger than 1 year hospitalized for LRTI between October 2009–April 2010 and/or October 2010-April 2011 are included (two consecutive RSV seasons). We present data on differences in LRTI disease severity comparing RSV positive premature infants (gestational age ≤ 36weeks) with RSV positive infants without risk factors (gestational age > 36weeks, no congenital heart disease, no bronchopulmonary dysplasia and no neuromuscular disease).

Results 3,474 evaluable subjects were included from 12 CEE countries. In 3,354 cases (96.5%) a RSV rapid test was performed: 1,423 cases (42.4%) were tested RSV positive. Among the RSV positive group, 266 infants were prematurely born (RSVppos); 1,034 presented without risk factors (RSVnorf). Mean hospitalization duration were 17 and 8 days respectively for RSVppos group and RSVnorf group (p<0.001). 41.4% of RSVppos required ICU hospitalization versus 12.6% RSVnorf (p<0.001). RSVppos exhibited a longer mean duration in ICU stay versus RSVnorf (13 days vs 6 days, p<0.001). 2.6% of RSVppos died during hospitalization versus 0.3% RSVnorf (p<0.001).

Conclusions Premature infants hospitalized for RSV LRTI exhibit a longer stay in hospital, more frequent and longer stay in ICU and a higher mortality compared with infants without risk factors.