Viral interference induced by live attenuated virus vaccine (OPV) can prevent otitis media

BACKGROUND: The goal of this study was to evaluate whether a live attenuated poliovirus vaccine (OPV) has clinically relevant interfering effect with non-polio infections causing otitis media in young children. METHODS: Open trial in which the intervention group (64 children) received OPV at the age of 2, 3, 6 and 12 months. The control group (250 children) received IPV (inactivated polio vaccine) at the age of 6 and 12 months. Clinical symptoms were recorded by a questionnaire at the age of 3, 6, 12, 18 and 24 months. RESULTS: Otitis media episodes were less frequent in the OPV than in the control group. A significant difference was seen at the age of 6–18 months (IRR = 0.76 [95% CI 0.59–0.94], P = 0.011) and was particularly clear among children, who attended daycare (IRR 0.37 [95% CI 0.19–0.71], P = 0.003). CONCLUSIONS: OPV provides some protection against otitis media. This effect may be mediated by viral interference with non-polio viruses.