The U.S. has experienced elevated flu levels for nine consecutive weeks, as of Jan. 20, according to the CDC's most recent update on the 2017-18 flu season published Friday.
The average duration for the past five flu seasons was about 16 weeks. "So, by this measure, we are about halfway there this season," said Dan Jernigan, MD, MPH, director of the influenza division in the CDC's National Center for Immunization. "That means we have several more weeks of flu to go."
Here are five more flu insights to know.
1. Most cases are still attributable to the H3N2 strain of influenza A, which is associated with more severe illness in the elderly and young children.
2. The CDC reported seven pediatric flu deaths for the week ending Jan. 20, which brings the pediatric death count to 37 for the current season. The agency tallied 148 deaths for the 2014-15 flu season, which the current season mirrors in terms of severity. "So clearly, we anticipate that there will be more pediatric deaths this year," said Dr. Jernigan.
3. Every state in the continental U.S. and Puerto Rico reported widespread flu activity for the third consecutive week, as of Jan. 20. "We often see different parts of the country 'light up' at different times, but for the past three weeks, the entire country has been experiencing lots of flu, all at the same time," Dr. Jernigan said.
4. The amount of outpatient visits for influenza-like illness was 6.6 percent for the week ending Jan. 20, surpassing the 2.2 percent national baseline. "This is the highest level of activity recorded since the 2009 H1N1 pandemic, which peaked at 7.7 percent," said Dr Jernigan.
5. The overall hospitalization rate was 41.9 per 100,000 population for the week ending Jan. 20. The CDC tallied 11,965 laboratory-confirmed flu-associated hospitalizations between Oct. 1, 2017, and Jan. 20, 2018.