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

General comparative trends are presented in Table 1 , were the Albany and Madang models are compared. For a pandemic in a developed country setting having a basic reproduction number R0 of 1.5 and an illness attack rate of 31.7%, the same pandemic characteristics applied in a PNG setting with no interventions activated resulted in higher rates of influenza transmission, with an attack rate of 46.6% and reproduction number R0 = 1.88 (Table 1) . Comparing the attack rates when interventions were activated, both intervention strategies (solely school closure and rigorous social distancing) were much less effective in the PNG setting compared to the Australian one. The mitigated illness attack rates in the PNG model were approximately 3 times higher than those in the Australian model with the interventions being 60% -70% less effective. Table 2 indicates where transmission that resulted in illness occurred, showing a significantly higher number and proportion of transmissions occurring in households, as opposed to other contact/transmission locations, in the Madang compared to the Australian model ( Table 1 ). The average household size in the PNG model is 2.5 times larger than that in Albany and this had a significant impact on the overall infection rate, making it noticeably higher in the PNG model.