After declining in the first two weeks of the year, flu activity jumped in the week ending Jan. 18, according to the CDC's most recent FluView report.
Six things to know:
1. The CDC estimates flu has caused 15 million illnesses, 140,000 hospitalizations and 8,200 deaths this season.
2. More than half of positive flu tests confirmed in public health laboratories have occurred in Americans under age 25. Only 12 percent involved adults age 65 and older. This trend has led to high levels of outpatient cases and lower levels of flu-related hospitalizations.
3. Thirty-five states experienced high flu-like illness activity in the week ending Jan. 18. Six states experienced moderate activity, eight states experienced low activity and Idaho experienced minimal activity.
4. The CDC confirmed 15 additional pediatric flu deaths, bringing the total to 54 for the 2019-20 season.
5. The flu's geographic spread remained the same for the week ending Jan. 18, with 48 states reporting widespread flu activity.
6. The overall flu-associated hospitalization rate was 24.1 per 100,000 people, up from 19.9 per 100,000 people a week prior. The CDC has recorded 7,013 flu-associated hospitalizations since Oct. 1, 2019.