CDC Reports Widespread Flu Activity Across U.S. with Highly Contagious Variant Spreading

The United States is in the midst of a significant flu season, with the Centers for Disease Control and Prevention (CDC) reporting “moderate to very high activity” of influenza-like illness across many states. The primary strain circulating this season is influenza A (H3N2), specifically subclade K, which health officials warn may cause more severe symptoms than typical seasonal flu variants.

Medical experts are emphasizing the importance of prevention tactics as cases rise nationwide. Dr. Samantha Picking, senior director of immunizations at Walgreens in Massachusetts, told Fox News Digital that understanding the contagion period is crucial for limiting spread.

“You are typically contagious with the flu for five to seven days after symptoms start,” Dr. Picking explained. “However, some groups remain contagious for longer periods. Young children and people with weakened immune systems can spread the virus for more than seven days, sometimes extending to two weeks or longer.”

A common misconception is that individuals are only contagious once symptoms appear. In reality, people can begin spreading the virus a day before experiencing any symptoms. According to Dr. Picking, the flu is most contagious during the first three to four days after symptoms emerge.

The typical incubation period—the time between exposure to the virus and symptom onset—is approximately two days, though it can range from one to four days. Even those with mild symptoms can transmit the virus to others.

For those beginning to feel sick or who have been exposed to someone with influenza, health experts recommend limiting contact with others. “To be safe and prevent spreading the virus, stay home until you’re fever-free for at least 24 hours without using fever-reducing medicine,” Dr. Picking advised. “For most healthy adults, this typically corresponds to five to seven days after symptoms begin.”

Additional precautions, such as wearing masks, are recommended even after returning to normal activities. Individuals should use their judgment and consult healthcare professionals if unsure about their contagion status.

The subclade K variant has been identified as particularly concerning this season. Dr. Neil Maniar, professor of public health practice at Northeastern University in Boston, noted, “It’s becoming evident that this is a pretty severe variant of the flu. Certainly, in other parts of the world where this variant has been prevalent, it’s caused some severe illness, and we’re seeing an aggressive flu season already.”

Despite the emergence of this more aggressive variant, Dr. Maniar reassured the public that “the vaccine still provides protection against serious illness resulting from the subclade K variant that seems to be going around.” This underscores the importance of vaccination, even as the flu season progresses.

Antiviral medications can help reduce the contagious period and severity of symptoms when started early. “These medications work best when started within two days of seeing symptoms,” Dr. Picking noted, recommending that interested individuals consult healthcare providers for personalized guidance.

Common flu symptoms include fever, chills, headache, fatigue, cough, sore throat, and runny nose. While most symptoms typically resolve within a week, some, such as cough, may persist for weeks afterward. “While a lingering cough is not necessarily a sign that you’re still contagious, it’s considerate to mask up and practice good cough etiquette when around others,” Dr. Picking advised.

Public health officials continue to emphasize preventive measures beyond vaccination, including frequent hand washing, staying home when sick, and avoiding close contact with individuals who are ill. These basic practices remain essential tools for reducing transmission during what appears to be developing into a particularly challenging flu season.

With the holiday travel season approaching, these precautions take on added importance as increased social gatherings and travel can accelerate the spread of respiratory illnesses like influenza.