Effectiveness of hand hygiene and provision of information in preventing influenza cases requiring hospitalization.

BACKGROUND The objective of the study was to investigate the effectiveness of non-pharmacological interventions in preventing cases of influenza requiring hospitalization. METHODS We performed a multicenter case-control study in 36 hospitals, in 2010 in Spain. Hospitalized influenza cases confirmed by reverse-transcription polymerase chain reaction and three matched controls (two hospital and one community control) per case were selected. The use of non-pharmacological measures seven days before the onset of symptoms (frequency of hand washing, use of alcohol-based hand sanitizers and handwashing after touching contaminated surfaces) was collected. RESULTS We studied 813 cases hospitalized for influenza and 2274 controls. The frequency of hand washing 5-10 times (adjusted odds ratio [aOR]=0.65) and >10 times (aOR=0.59) and handwashing after contact with contaminated surfaces (aOR=0.65) were protective factors and were dose-responsive (p<0.001). Alcohol-based hand sanitizers were associated with marginal benefits (aOR=0.82). CONCLUSIONS Frequent handwashing should be recommended to prevent influenza cases requiring hospitalization.