Yes, flu is circulating widely across the United States. The 2024-25 season brought co-circulation of two influenza A strains at nearly equal levels, and cumulative hospitalization rates reached the highest point since the 2010-11 season. If you’re feeling sick right now or trying to avoid getting sick, here’s what you need to know about what’s going around and how to protect yourself.
Which Flu Strains Are Circulating
Influenza A dominated this season, making up roughly 90% of all detected flu viruses. Within that group, two subtypes circulated in almost equal proportion: H1N1 accounted for about 53% of subtyped influenza A viruses, and H3N2 made up the remaining 47%. A small number of influenza B viruses were also detected, all belonging to the Victoria lineage.
Having two influenza A subtypes circulate simultaneously at nearly equal levels is notable because it means different waves can hit different communities at different times, extending the overall season. It also means a person could potentially catch one subtype and later be infected by the other.
How Bad Is This Season
By several measures, this has been a severe season. The cumulative hospitalization rate reached 59.5 per 100,000 people, the highest at this point in the season since 2010-11. Children have been hit particularly hard, with pediatric hospitalization rates ranking as the second highest in that same 15-year window. A total of 71 pediatric flu-related deaths were reported.
Flu season typically runs from fall through winter, with activity most often peaking in February. Over the past 40 years, February has been the peak month in 18 separate seasons, followed by December (9 seasons), January and March (6 each). So if you’re reading this in winter months, you’re likely in or near the peak of activity.
Flu vs. COVID vs. a Cold
All three can make you miserable, but there are some reliable ways to tell them apart. The flu typically hits fast, with symptoms appearing one to four days after exposure. COVID takes longer to develop, usually two to 14 days. A cold tends to build gradually without much fever.
The biggest distinguishing features:
- Fever: Usually present with the flu, only sometimes with COVID, and rare with a cold.
- Muscle aches: Common with the flu, occasional with COVID, and essentially absent with a cold.
- Loss of taste or smell: Common early in COVID (often without a stuffy nose), rare with the flu, and absent with a cold.
- Fatigue: Significant with both flu and COVID, but not typical of a cold.
- Cough: Usually present with the flu, sometimes with COVID (tends to be dry), and sometimes with a cold.
If you’re unsure, rapid tests for both flu and COVID are available at most pharmacies and doctor’s offices. Knowing which virus you have matters because the treatment options are different.
Why the Treatment Window Matters
Antiviral medications for the flu work best when started within 48 hours of your first symptoms. That’s a tight window, and it’s the main reason it’s worth getting tested early rather than waiting to see if you improve on your own. Several prescription antivirals are available, including pills and inhaled options, for both adults and children as young as five (some are approved for even younger patients).
Starting treatment within those first two days can shorten the duration of illness, reduce severity, and lower the risk of complications like pneumonia. After 48 hours, antivirals can still help people at high risk for serious illness, including young children, adults over 65, pregnant women, and people with chronic health conditions. But the benefit drops the longer you wait.
How the Flu Spreads (and Lingers)
Flu spreads primarily through respiratory droplets when an infected person coughs, sneezes, or talks. But surfaces play a role too. Influenza A and B viruses survive 24 to 48 hours on hard, nonporous surfaces like stainless steel, plastic, and doorknobs. On softer materials like cloth and paper, they last less than 8 to 12 hours.
The virus can transfer from a contaminated surface to your hands and remain viable on skin for about five minutes. That’s a short window, but it’s enough time to touch your face. Regular handwashing remains one of the simplest ways to cut transmission, especially after touching shared surfaces in public spaces.
How Well This Year’s Vaccine Matches
The 2024-25 flu vaccine was designed to target the specific viral groups that ended up circulating. The H3N2 viruses detected this season all belonged to the same genetic group as the strain included in the vaccine. The H1N1 viruses also fell within the expected lineage, though some genetic drift was observed, which is normal as flu viruses continuously evolve.
Vaccine composition is reviewed and updated every year to keep pace with these changes. Even in seasons where the match isn’t perfect, vaccination reduces the likelihood of severe illness and hospitalization. For this season, the alignment between vaccine strains and circulating viruses was generally favorable.
Practical Steps if You’re Sick Now
If you’ve developed sudden fever, body aches, and fatigue, those are hallmarks of the flu. Get tested within the first day or two if possible, since that’s when antiviral treatment is most effective. Stay home to avoid spreading the virus. Most healthy adults are contagious from one day before symptoms start through five to seven days after becoming sick.
Rest and fluids are still the foundation of recovery for most people. Fever and body aches typically improve within three to five days, though cough and fatigue can linger for two weeks or more. If you develop difficulty breathing, persistent chest pain, confusion, or your fever returns after improving, those are signs of a complication that needs medical attention.