2015-07-30

Recent advances in mathematical modeling and inference methodologies have enabled development of systems capable of forecasting seasonal influenza epidemics in temperate regions in real-time. However, in subtropical and tropical regions, influenza epidemics can occur throughout the year, making routine forecast of influenza more challenging. Here we develop and report forecast systems that are able to predict irregular non-seasonal influenza epidemics, using either the ensemble adjustment Kalman filter or a modified particle filter in conjunction with a susceptible-infected-recovered (SIR) model. We applied these model-filter systems to retrospectively forecast influenza epidemics in Hong Kong from January 1998 to December 2013, including the 2009 pandemic. The forecast systems were able to forecast both the peak timing and peak magnitude for 44 epidemics in 16 years caused by individual influenza strains (i.e., seasonal influenza A(H1N1), pandemic A(H1N1), A(H3N2), and B), as well as 19 aggregate epidemics caused by one or more of these influenza strains. Average forecast accuracies were 37% (for both peak timing and magnitude) at 1-3 week leads, and 51% (peak timing) and 50% (peak magnitude) at 0 lead. Forecast accuracy increased as the spread of a given forecast ensemble decreased; the forecast accuracy for peak timing (peak magnitude) increased up to 43% (45%) for H1N1, 93% (89%) for H3N2, and 53% (68%) for influenza B at 1-3 week leads. These findings suggest that accurate forecasts can be made at least 3 weeks in advance for subtropical and tropical regions.

Yang, W, Cowling, BJ, Lau, EHY, Shaman, J. (2015). Data from: Forecasting Influenza Epidemics in Hong Kong. [Data File]. All relevant data are within the paper and its Supporting Information files. Click on “Linked Publications” to access the publication and access supporting information on figshare at https://figshare.com/articles/_Forecasting_Influenza_Epidemics_in_Hong_Kong_/1498873

sir

ensemble adjustment Kalman filter

Average forecast accuracies

peak magnitude

1N

influenza strains

Hong Kong

Forecasting Influenza Epidemics

retrospectively forecast influenza epidemics

3n

peak timing

influenza epidemics

forecast accuracy

report forecast systems