Flu activity is increasing across many parts of the United States, with cases and hospitalizations surging earlier than typically observed, the Centers for Disease Control and Prevention (CDC) warned. The agency noted that flu levels are higher than usual for this time of year, continuing to rise nationally.
As of the week ending October 31, the CDC estimated that over 1.7 million people had been sickened by the flu, a 70 percent increase from the previous week. Hospitalizations also saw a significant jump, with an estimated 25,000 people hospitalized, up 56 percent from the week prior. An estimated 1,400 deaths were attributed to flu infections, a 55 percent increase in a week.
For comparison, flu levels were considerably lower at the same time last year, with the CDC not publishing estimates until mid-November. Cases did not reach current levels until the end of that month. The current surge has seen 26 states report an uptick in flu levels, with Louisiana and South Carolina reporting high activity, and Washington, California, Texas, Florida, and Oregon reporting moderate levels.
Typically, the flu season begins to circulate in October, peaks between December and February, and declines by May. However, this year, flu levels began rising as early as the week ending August 8 and have continued their upward trend. Unusually, cases initially started to rise on the West Coast before spreading nationwide.
The early increase in cases is linked to the H1N1 strain of the virus, which was responsible for the 2009 pandemic. Experts believe this strain, which has acquired a new mutation called G155E, may be better at evading previous immunity, though there is no evidence it causes more severe infections. Health officials emphasize that an earlier start does not necessarily predict a more severe season.
The weekly flu hospitalization rate has increased to 2.5 per 100,000 individuals, up from 1.8. Two flu-associated deaths among children have been reported, an increase from one the previous week.
Experts are urging Americans to get their flu shots as soon as possible. The flu vaccine is estimated to reduce the risk of infection by 34 percent and hospitalization by 30 percent, although effectiveness varies annually. It takes at least two weeks for the vaccine to become fully effective. The CDC recommends the vaccine for everyone six months and older, and it is typically covered by health insurance. Individuals over 65, young children, and those with underlying health conditions are at higher risk of severe illness.
Influenza is a highly contagious respiratory infection that affects approximately 8 percent of the U.S. population annually, causing symptoms such as fever, cough, sore throat, and fatigue. Complications can include pneumonia and severe brain dysfunction. The H1N1 strain was last dominant during the 2023-2024 flu season and was linked to millions of illnesses and thousands of hospitalizations during the 2009 swine flu pandemic.