The Centers for Disease Control and Prevention (CDC) provides weekly surveillance data of confirmed flu and outpatient visits for influenza-like illnesses from public health and clinical laboratories around the nation. But these data lag real-time activity and not everyone who gets sick with the flu goes to the hospital. This study was published in Science Translational Medicine .

This study aims to bridge the gap between epidemiology and evolutionary theory to give forecasters advanced warning about the severity of the most dangerous flu strains. The result is forecasting for the season before anyone is reporting getting sick.

To advance flu forecasting efforts , the agency launched its first forecasting challenge during the 2013-2014 flu season with a first-place prize of $ 75,000. Since then, the monetary award has gone away, but teams have continued to participate for the honor of providing the most accurate forecast for the start of the flu season , how bad it will get over the course of the season, and when cases will peak .

Flu forecasts before flu season starts

This study aims to bridge the gap between epidemiology and evolutionary theory to give forecasters advanced warning about the severity of the most dangerous flu strains . The result is forecasting for the season before anyone is reporting getting sick. "This is much more ambitious than what we have attempted, for which the authors should be lauded," Rosenfeld says.

The new report is specific to H3N2, a seasonal influenza A subtype that has been circulating around the human population since 1968. Using an estimate of how likely it is the virus is going to change based on the mutations it's demonstrated in the past; the model predicts how many people are going to get sick with H3N2 during the upcoming season.

Predictions for 2017-2018 flu season

Pascual said, “Our analysis for this year showed that the virus is already changing in a significant way.” “We predict an outbreak that is above average but moderate, not severe, because last year was such a bad season.”  

Also, this year, the CDC is experimenting with breaking down the forecasts by state, in addition to having national and regional predictions. “This year, we are piloting with teams at the state level. We just started to get state-level forecasts a couple weeks ago,” says epidemiologist and modeler Matthew Biggerstaff of the Influenza Division in the National Center for Immunization and Respiratory Diseases at CDC.

Not all states are participating. "It will be useful to see if teams that incorporate state data have higher accuracies than states that do not," he adds. Illinois, for example, currently predicting outcomes like the national average, though perhaps peaking slightly sooner.