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Flu season may have peaked but activity remains "elevated"

Data: Centers for Disease Control; Chart: Axios Visuals

The flu season may have peaked a couple weeks ago, but infection rates remain elevated, according to the Centers for Disease Control and Prevention. The CDC also announced another 13 reported influenza-associated deaths in children during the week ending Feb. 17, raising the total to 97 pediatric deaths so far this season.

"It looks like influenza-like-illness has peaked for the 2017-2018 season, but flu activity remains high and there are several more weeks of flu activity to come."
— CDC spokesman Ian Branam tells Axios

By the numbers, for the week ending Feb. 17, per CDC :

  • The CDC bases its flu estimates on the percentage of people going to see a doctor for an influenza-like illness (ILI). For the week ending Feb. 17, that rate was 6.4%, which is lower than the previous week (7.5%). The peak appears to have occurred the week ending Feb. 3, when the rate hit 7.7%.
  • In patients testing positive for influenza, 65% had Influenza Type A (roughly three-fourths of those had the more serious H3N2 strain) and 35% had Influenza Type B.
  • Widespread influenza activity was reported by Puerto Rico and all states, except for Hawaii and Oregon which, along with D.C. and Guam, shows local influenza activity. No influenza was reported by the U.S. Virgin Islands.

How the CDC forecasts the flu: Matthew Biggerstaff, epidemiologist in CDC's influenza division, tells Axios the CDC started a competition five years ago for non-government institutions to predict the flu season. The teams are given a set of targets they need to track for the challenge.

  • This year more than 20 different groups are tracking at least 30 different forecasts, which needs to include CDC's ILI data for comparison.
  • Each group is voluntary and uses their own grants or other funding to pay for their forecasting.

Private sector viewpoint: One of the competitors in the challenge, the Los Alamos National Laboratory, says they've found social media to be helpful in their forecasting — although they still conduct one forecast using traditional methods and one that adds social media input (this year, they are using Google health trends).

For this year, David Osthus, leader of the LANL's forecasting team, says their short-term forecast for the peak week was: 40% Feb. 3, 40% Feb. 10, and 10% Feb. 17. "Looks like the forecast was correct," he says.

Why forecasts are needed: Biggerstaff says forecasting is important to get the vaccination message out on time, to help hospitals and clinics manage their staffing needs and medicine distribution, and to decide possible school closures.

Separately, there have been some updates on the research front:

  • Fortune reports that Japan fast-tracked its approval of new antiviral drug Xofluza, which is said to kill the flu virus in just one day. It has not yet been approved in the U.S.
  • The Wall Street Journal says new Food and Drug Administration regulations have started to improve the quality of flu testing.