AFP and poliovirus infection: The estimated median monthly sensitivity of AFP surveillance for poliovirus infection in Australia among children aged less than 15 years, assuming no difference in the risk of infection with age, was 8.2% (5th-95th percentiles 5.3-12.1%, mean 8.4%) for a design prevalence of 10-5, and 0.9% (5th-95th percentiles 0.5-1.3%, mean 0.9%) for a design prevalence of 10-6 respectively.