Flu activity is rising sharply across much of the US, health officials say, 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 regions.
In its latest surveillance 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, with most of the affected states located in the South, West, Midwest and Northeast.
Louisiana recorded ‘very high’ flu activity. Six other states — Washington, Oregon, California, Texas, Tennessee and South Carolina — reported ‘high’ levels.
Eight additional states — Idaho, New Mexico, Colorado, Hawaii, Florida, New York, New Jersey and Massachusetts — reported ‘moderate’ flu activity.
By comparison, only seven states reported moderate or high flu levels the previous week. Louisiana and South Carolina had high activity, while Washington, California, Texas, Florida and Oregon recorded moderate levels.
An estimated 36,000-plus people had been hospitalized with flu, up 44 percent from the prior week. Approximately 2,100 people had died while infected with the virus, representing a 50 percent weekly increase.
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 CDC issued its first estimate in 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 November.
The share of positive flu tests rose to 11 percent, compared with 9.1 percent the week before. Outpatient visits for respiratory illness also increased, reaching 3.2 percent from 2.8 percent.
The CDC’s latest update also showed that the weekly flu hospitalization rate climbed to 2.9 per 100,000 people, up from 2.5 per 100,000.
Adults aged 65 and older had the highest rate of flu-related hospitalization so far this season, according to the data.
Flu viruses typically begin circulating in October, peak between December and February, and then decline through May.
This year, however, CDC data showed flu activity beginning to increase during the week ending August 8, with levels continuing to rise afterward.
Flu activity also usually emerges 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 — a pattern doctors described as unusual.
The early nationwide increase has been associated with the H1N1 strain, the same strain linked to the 2009 flu pandemic, which sickened 60 million people and led to more than 240,000 hospitalizations.
Experts believe H1N1 is responsible for most infections across the country and has developed a new mutation known as G155E. The mutation could 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-than-usual flu season does not necessarily mean the season will be more severe than those in previous years.
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The states reporting increased 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, Florida.
Flu activity is accelerating across much of the US, with seven states reporting ‘high’ or ‘very high’ case levels, according to health officials.
Health experts are urging Americans to receive their 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 say the vaccine takes at least two weeks to provide protection.
The shot is recommended for everyone aged six months and older and is generally covered by health insurance. Adults over 65, young children and people with underlying health conditions face a greater risk of severe flu complications.
Influenza, commonly called the flu, is one of the most widespread and contagious respiratory infections, affecting roughly 8 percent of the US population each year.
Symptoms can include fever, cough, sore throat, a blocked or runny nose, headache and fatigue. In some cases, flu can cause serious complications such as 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 humans and animals. Influenza B is generally found only in people and is typically linked to less severe infections.
Influenza C is far less common than types A and B and usually causes mild illness in humans.
Most people recover within about a week, but 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 ‘super flu’ surge was driven by subclade K, a heavily mutated variant of the Influenza A (H3N2) virus that triggered a rapid and severe rise in cases 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 unfamiliar to people’s immune systems, many were more vulnerable to 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 serious illness, particularly in children. Reported signs included fevers lasting a week and coughing that caused breathing difficulties.
The 2025-2026 respiratory season recorded at least 32 million flu cases, according to the CDC. There were approximately 390,000 hospitalizations and 24,000 deaths.
H1N1, the dominant strain this year, was last the leading strain during the 2023-2024 flu season.
To reduce the risk of flu, 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 severe cases, doctors may prescribe antiviral drugs such as Tamiflu.
