Currently, the United States is experiencing a significant surge in influenza cases, primarily driven by a variant of the influenza A (H3N2) virus known as “subclade K,” marking the official start of the 2025-2026 season.
Influenza infections are clearly on the rise both nationwide and in Florida as of December 2025. The predominant strain is Influenza A (H3N2), with a new variant known as “subclade K” gaining ground.
It’s important to recognize the symptoms to watch for and the most effective measures to protect yourself, based on the latest reports from the CDC and health authorities.
Warning Signs
This season, symptoms are similar to the classic ones but have been reported to appear suddenly and intensely.
- Fever or chills (though fever doesn’t always occur).
- Severe muscle and body aches (a hallmark of this H3N2 variant).
- Headache and extreme fatigue (tiredness).
- Cough and sore throat.
- Congestion or runny nose.
- Note: In children, vomiting and diarrhea are more common alongside respiratory symptoms.
How to Avoid Infection
Since the virus is spreading rapidly in states like New York, Colorado, and New Jersey, it’s recommended to reinforce these four barriers:
- Vaccination (The Priority):
- Even with news about the new variant, the current vaccine remains your best tool. Even if you get infected, the vaccine prevents the illness from becoming severe and leading to hospitalization.
- Proper Hygiene:
- Wash your hands frequently with soap and water (or use hand sanitizer with at least 60% alcohol).
- Avoid touching your eyes, nose, and mouth; these are the main entry points for the virus.
- Smart Distancing:
- If you see someone coughing or sneezing, keep your distance.
- Consider wearing a mask in crowded indoor spaces (public transportation, airports) during these peak weeks.
- Ventilation:
- The virus concentrates in enclosed spaces. If you’re hosting family gatherings, try to ventilate the area by occasionally opening windows.
What to Do If You Already Have Symptoms
- Stay home: Don’t go to work or school to break the chain of transmission.
- Antiviral treatment: If you’re in a high-risk group (young children, adults over 65, people with asthma or diabetes), contact your doctor immediately. Antivirals work best if taken within the first 48 hours.
Situation in the United States:
- Widespread increase: Flu activity is rising in most areas of the country, marking the official start of the 2025-2026 season. Key indicators, such as clinic and emergency room visits for respiratory illnesses, have increased, surpassing the national baseline.
- Subclade K: This new H3N2 variant is becoming dominant and appears to have mutations that allow it to evade existing immunity, facilitating its spread. While it doesn’t seem to cause more severe illness, its higher transmissibility could lead to a greater total number of sick individuals and, consequently, more severe cases.
- Hospitalizations and deaths: An increase in hospitalization rates and flu-related deaths has been observed. The CDC has already confirmed three pediatric deaths associated with influenza this season.
- Estimates: The CDC estimates that millions of cases, tens of thousands of hospitalizations, and thousands of deaths from the flu have already occurred this season.
Situation in Florida:
- Rising trend: The Florida Department of Health reports an increase in the flu positivity rate and emergency room visits for flu-related causes in the most recent week (December 7–13, 2025).
- Predominant strain: As nationwide, the Influenza A H3 strain is the most common in the state.
- Outbreaks: Weekly outbreaks have been reported, indicating active community transmission.
- Ongoing surveillance: Florida health authorities maintain year-round surveillance, though the typical flu season extends through May.
Recommendations:
Given this rise in infections, health authorities emphasize the importance of vaccination as the primary preventive measure, as even with the new variant, the vaccine is expected to provide decent protection and reduce the severity of the illness. Basic hygiene measures, such as frequent handwashing and covering your mouth when coughing or sneezing, are also recommended.
