Clinical attack rate in the USA. The number of clinical A/H1N1 cases in the 2009 pandemic as estimated by the US Centers for Disease Control and Prevention (gray) and by two different stochastic forecast output (SFO) sets simulated by the Global Epidemic and Mobility (GLEAM) computational model, at six different dates between April 2009 and March 2010. The simulated results corresponded to the reference SFO set with vaccination and to the pre-exposure immunity SFO set with vaccinations, with the proportion of asymptomatic infections, p
, set to 45%. The bar indicates the median value and the error bar indicates the corresponding 95% reference range.