Flu activity is rising sharply across much of the US, health officials warn, with seven states now reporting “high” or “very high” levels.
The Centers for Disease Control and Prevention (CDC) said Friday that flu activity was “higher than typically observed at this time of year” and continued to climb in many parts of the country.
In its latest update, the agency estimated that more than 2.6 million people had been infected with influenza by the week ending November 7—a 53 percent increase from the previous week.
Flu activity increased in 38 states during the latest reporting period, spanning the South, West, Midwest and Northeast.
Louisiana was the only state classified as having “very high” flu activity. Six others—Washington, Oregon, California, Texas, Tennessee and South Carolina—recorded “high” levels.
Eight additional states—Idaho, New Mexico, Colorado, Hawaii, Florida, New York, New Jersey and Massachusetts—reported “moderate” flu activity.
By comparison, just seven states had moderate or high flu activity the previous week. Louisiana and South Carolina were categorized as high, while Washington, California, Texas, Florida and Oregon reported moderate levels.
An estimated 36,000-plus people had also been hospitalized with flu, a 44 percent increase in one week. About 2,100 people were estimated to have died while infected with influenza, marking a 50 percent weekly rise.
At the same point last year, flu activity was low enough that health officials had not yet released estimates for cases, hospitalizations or deaths. The first estimate came for the week ending November 15, when more than 650,000 illnesses were believed to have occurred. Case numbers did not reach this year’s level until the end of that month.
The percentage of positive flu tests rose to 11 percent from 9.1 percent. Outpatient visits for respiratory illness also increased, reaching 3.2 percent compared with 2.8 percent the week before.
The CDC’s latest report also showed that the weekly flu hospitalization rate rose from 2.5 to 2.9 per 100,000 people.
Adults aged 65 and older have experienced the highest flu-related hospitalization rates so far this season, according to the data.
Flu transmission typically begins in October, peaks between December and February, and then declines through May.
This season, however, CDC data showed that flu activity had already started increasing during the week ending August 8 and has continued to rise.
Flu levels also generally increase first in the South before spreading to other parts of the country.
This year, official data indicated that activity began rising first on the West Coast—an unusual pattern that doctors noted.
The early nationwide increase has been linked to H1N1, the strain responsible for the 2009 flu pandemic, which sickened 60 million people and led to more than 240,000 hospitalizations.
Experts say H1N1 is responsible for most cases in the US and has developed a new mutation known as G155E. The mutation may help the virus evade existing immunity and cause infection, although there is no evidence that it leads to more severe illness.
CDC health officials have cautioned that an earlier start to flu season does not automatically mean the season will be more severe than in previous years.
The states reporting an increase in flu activity were: Alaska, Washington, Idaho, Wisconsin, Vermont, New Hampshire, Massachusetts, Oregon, Nevada, Wyoming, Indiana, Ohio, Pennsylvania, New York, Connecticut, Rhode Island, California, Colorado, Missouri, Kentucky, Maryland, New Jersey, Arizona, New Mexico, Kansas, Tennessee, Virginia, North Carolina, Oklahoma, Louisiana, Mississippi, Alabama, Georgia, South Carolina, Hawaii, Texas and Florida.
Flu activity is rising sharply across much of the US, health officials warn, with seven states now reporting “high” or “very high” case rates.
Health experts are urging Americans to get their seasonal flu vaccine as soon as possible.
Estimates indicate that flu vaccination reduces the risk of infection by 34 percent and hospitalization by 30 percent, although effectiveness varies from year to year. Doctors emphasize that the vaccine takes at least two weeks to provide protection.
The flu vaccine is recommended for everyone aged six months and older and is typically covered by health insurance. Adults over 65, young children and people with underlying health conditions face a greater risk of severe influenza complications.
Influenza, commonly called the flu, is one of the most widespread and contagious respiratory infections. It affects roughly 8 percent of the US population each year.
Common symptoms include fever, cough, sore throat, a stuffy nose, headache and fatigue. In some cases, influenza can cause serious complications, including pneumonia and influenza-associated encephalopathy, a severe form of brain dysfunction.
Three types of influenza viruses can cause illness: types A, B and C.
Influenza A can infect both people and animals. Influenza B is generally found only in humans and is typically linked to less severe infections.
Influenza C is much less common than types A and B and usually causes mild illness in people.
Although most people recover within about a week, some develop complications such as pneumonia, which can be life-threatening and may require medical care.
Last year brought an especially severe flu season, as a surge in “super flu” cases was driven by subclade K, a heavily mutated version of the influenza A (H3N2) virus that triggered a rapid and severe rise in infections nationwide.
The strain responsible for the 2009 swine flu pandemic has been linked to an early rise in US flu cases this year.
Because the strain was new to people’s immune systems, many were especially vulnerable and faced a higher risk of severe illness requiring hospitalization.
Symptoms were similar to those caused by other flu strains, but experts warned that the “super flu” variant was producing more severe illness, particularly in children. Reported signs included fevers lasting a week and coughing that caused difficulty breathing.
The 2025-2026 respiratory season recorded at least 32 million flu cases, according to the CDC. About 390,000 people were hospitalized and 24,000 died.
H1N1, the dominant strain this year, was last the leading strain during the 2023-2024 flu season.
To reduce the risk of infection, health officials recommend washing hands regularly and avoiding close contact with people experiencing flu-like symptoms.
Treatment generally involves rest, plenty of fluids and over-the-counter medicines. In more serious cases, doctors may prescribe antiviral drugs such as Tamiflu.