Pandemic influenza in Papua New Guinea: a modelling study comparison with pandemic spread in a developed country

Milne, George J; Baskaran, Pravin; Halder, Nilimesh; Karl, Stephan; Kelso, Joel

The transmission coefficient β was initially chosen to give an epidemic with a final attack rate of 17.4% which is consistent with seasonal influenza as estimated in Table 3 of 6 . To achieve simulations for a particular basic reproduction number, β was increased from this baseline value; details of the procedure for estimating β and R0 are given in 7 . A pandemic with a basic reproduction number of 1.5, and which has been used in this study, corresponds to some estimations of the 2009 H1N1 pandemic [8] [9] [10] [11] and the 1957 and 1968 pandemics. 12 13 The susceptibility parameter Susc(Is) is a function which may be dependent on the age of the susceptible individual, to capture age-varying susceptibility to transmission. This age variance may be due to either partial prior immunity, as thought to have occurred in the 2009 pandemic, or age-related differences in contact behaviour. In the work reported here a flat, non age-varying susceptibility was used to reflect a novel pandemic strain where none of the population has any prior immunity, as would be the case if H5N1 becomes human transmissible.