BACKGROUND In very low birth weight (VLBW) infants, obstructive bronchitis is a frequent cause of hospital re-admission. For VLBW infants, early vaccinations starting at 2 months after birth have been recommended. OBJECTIVE To analyze risk factors for bronchitis during the first year after discharge and the effects of in-hospital standard vaccination (hexavalent/pneumococci) and/or RSV immunoprophylaxis with palivizumab. METHODS A standardized questionnaire was sent to the parents of VLBW infants 7 month after discharge. The reported episodes of bronchitis were correlated with clinically recorded parameters including risk factors for pulmonary morbidity. The effects of in-hospital vaccination were assessed in a subgroup discharged after day 60. RESULTS A sample of 1 967 responses of infants born 2009-2011 was analyzed. Risk factors for bronchitis were male gender and older siblings. 24% of the population had episodes of bronchitis. In the subgroup discharged after day 60, episodes of bronchitis were reported for 31% of infants who were not vaccinated in-hospital. A significant reduction of the bronchitis rate was found in infants who received palivizumab±standard vaccination (17% bronchitis, p=0.003). Interestingly, in-hospital standard vaccination without RSV immunoprophylaxis was protective (20% bronchitis; p=0.037) as well. CONCLUSIONS Non-vaccinated male VLBW infants with older siblings are at increased risk for bronchitis during the first year after discharge. Vaccination according to schedule seems to have protective effects, while underlying mechanisms are unknown. The rate of timely vaccination in preterm infants should be increased.