As of early March 2026, the flu is the dominant virus circulating in the United States, accounting for 2.5% of all emergency department visits nationally. COVID-19 and RSV are also still active but at lower levels. Overall, the amount of respiratory illness sending people to seek care is low, though specific viruses remain elevated in certain regions.
Flu Is Leading This Season
Influenza is the biggest driver of respiratory illness right now. Nationally, flu activity remains elevated, and 29 states or jurisdictions are reporting high or very high activity levels. The strain doing most of the work is influenza A(H3N2), which has dominated all season. Among the H3N2 viruses the CDC has genetically analyzed since late September 2025, about 90% belong to a single genetic group called subclade K.
Influenza B is also picking up. While it makes up a smaller share of cases (roughly 13% of positive flu tests in clinical labs), B activity is increasing nationally even as A activity holds steady. All of the influenza B viruses tested so far this season belong to the Victoria lineage. Activity levels vary by region: parts of the South, Midwest, and West Coast saw increases in recent weeks, while the Northeast saw a dip.
COVID-19 Is Declining but Still Around
COVID-19 activity is on the way down nationally, making up about 0.5% of emergency department visits as of late February 2026. That said, some areas of the country still have elevated levels. The World Health Organization is monitoring several SARS-CoV-2 lineages, including KP.3.1.1, NB.1.8.1, and XFG, all descendants of the JN.1 family that has been circulating for over a year. None of these variants have been flagged as causing more severe illness or notably different symptoms compared to earlier strains.
RSV Is Elevated in Some Regions
RSV (respiratory syncytial virus) accounts for about 0.6% of emergency department visits nationwide. While that number is modest, RSV activity is elevated and increasing in parts of the country. RSV tends to be most dangerous for babies under one year old and adults 75 and older, so even moderate activity levels matter for those groups.
How to Tell Which Virus You Might Have
The honest answer: you often can’t tell from symptoms alone, because flu, COVID-19, RSV, and even common colds overlap heavily. But some patterns can offer clues.
Flu tends to hit fast and hard. Fever, body aches, headache, and exhaustion often come on within hours. COVID-19 typically brings a sore throat, congestion, and fatigue, and is more likely than a cold to cause headache, muscle aches, or a lingering cough. A loss of taste or smell, while less common than it was in earlier pandemic waves, still points more toward COVID-19 than anything else. RSV in adults often looks like a bad cold with heavy congestion and cough, but in infants it can cause wheezing, difficulty breathing, and poor feeding.
If you’re in a high-risk group or your symptoms are severe, a rapid test (for flu and COVID-19, or a combination test) is the most reliable way to know what you’re dealing with. Knowing matters because antiviral treatments for both flu and COVID-19 work best when started within the first day or two of symptoms.
When You Can Go Back to Normal Activities
The CDC uses the same guidance for all common respiratory viruses: you can return to your usual routine once your symptoms have been improving overall for at least 24 hours, and any fever has been gone for at least 24 hours without fever-reducing medication. This applies to flu, COVID-19, RSV, and other respiratory infections.
After that 24-hour threshold, you’re not necessarily done being contagious. The CDC recommends taking extra precautions for the next five days: wearing a well-fitting mask in crowded or indoor settings, improving ventilation where you can, washing your hands more frequently, and keeping some distance from others. Testing can also help you gauge whether you’re still likely to spread the virus.
Vaccines Still Available This Season
Updated 2024-2025 vaccines for both flu and COVID-19 are recommended for everyone six months and older. If you haven’t gotten either one yet, it’s not too late. Respiratory viruses can circulate well into spring, and protection from vaccination typically lasts several months.
RSV protection works differently depending on your age. Babies under eight months can receive an antibody treatment (nirsevimab) that provides passive protection, or their mothers can be vaccinated during pregnancy at 32 to 36 weeks. For older adults, a single RSV vaccine dose is recommended for everyone 75 and older, and for adults 60 to 74 with conditions that put them at higher risk. If you received an RSV vaccine last year, you don’t need another one this season.
Staying Ahead of What’s Circulating
Respiratory virus season typically peaks between December and March, so late winter is when you’re most likely to encounter these viruses. The CDC’s respiratory virus dashboard updates weekly and breaks down activity by state, which can help you gauge risk in your specific area. Right now, the overall picture is manageable: flu is the main concern, COVID-19 is fading, and RSV bears watching in certain regions. Basic precautions, staying home when sick, good hand hygiene, and up-to-date vaccinations, remain the most effective tools for keeping yourself and the people around you healthy.