Scientists can now forecast flu outbreaks in subtropical climates

The technique predicted the peak timing of the outbreak three weeks in advance of the actual peak with accuracy as high as 93 per cent.

Prediction accuracy varied depending on the strength of the outbreak and how far in advance the prediction was made.

In general, forecasts for specific strains were more accurate than those for aggregate epidemics, and the peak and magnitude of outbreaks were more accurate than the timing of their onset or their duration.

"Individuals may choose to get a flu vaccine to protect themselves against infection, while officials can anticipate how many vaccines and other supplies are needed, as well as the number of clinicians and nurses needed," said senior author Jeffrey Shaman, associate professor of Environmental Health Sciences at the Mailman School.

Seasonal influenza outbreaks in temperate climates like the US are restricted to the winter months. By contrast, outbreaks in the subtropics such as Hong Kong happen year-round.

In addition, outbreak intensity, duration, and timing are more variable in the subtropics than in temperate regions.

"The irregularity of flu outbreaks in subtropical climates makes forecasting more challenging," said first author Wan Yang, an associate research scientist at the Mailman School.

Researchers modified the flu forecasting system used in the US to account for the dynamics of a subtropical climate, adding mathematical techniques that prompt the system to recalibrate itself and let go of certain assumptions.

The study was published in the journal PLOS Computational Biology.