The flu circulating right now is primarily seasonal influenza, and the 2024-2025 season has been unusually severe. With a cumulative hospitalization rate of 161.5 per 100,000 people, this season produced the highest flu hospitalization numbers recorded since the CDC began tracking in 2010. Alongside seasonal flu, a separate strain of bird flu (H5N1) has been making headlines, though it poses a low risk to the general public.
Why This Season Has Been Worse
Between late September 2024 and August 2025, more than 545,000 people were hospitalized with flu across the United States. The peak of the season hit later and substantially harder than the previous three years. The dominant circulating strains have been influenza A viruses, specifically H1N1 and H3N2 subtypes, along with influenza B/Victoria lineage viruses.
What made this season stand out wasn’t a dramatically different virus. It was a combination of factors: the timing of the wave, the intensity of spread, and likely gaps in vaccination coverage. H3N2 strains in particular tend to cause more hospitalizations, especially among older adults, and they played a significant role this season.
Symptoms to Watch For
Seasonal flu symptoms haven’t changed much from what you’d expect: fever, cough, sore throat, body aches, headaches, and fatigue. Some people also experience vomiting or diarrhea, particularly children. What distinguishes flu from a common cold is the speed of onset. Flu tends to hit suddenly and hard, while colds build gradually.
If you’re wondering whether you might have bird flu instead, the risk is extremely low unless you’ve had direct contact with infected poultry or dairy cattle. Among the 71 confirmed U.S. bird flu cases since February 2024, the most common symptom has been eye redness, not the respiratory symptoms typical of seasonal flu. Nearly all of those cases occurred in dairy and poultry workers. There is no known person-to-person spread of H5N1 at this time.
How Well the Vaccine Worked
The flu vaccine this season provided moderate protection, which is fairly typical. For adults, it reduced outpatient flu visits by roughly 36 to 56 percent depending on the study, and cut hospitalizations by 41 to 55 percent. Children and adolescents fared better: vaccination reduced outpatient visits by about 59 to 60 percent and prevented hospitalizations by 63 to 78 percent.
Those numbers might sound underwhelming compared to, say, a measles vaccine that’s over 95 percent effective. But even a 50 percent reduction in your odds of ending up in the hospital is significant, especially for older adults. Among people 65 and older, vaccination reduced hospitalizations by 38 to 57 percent this season.
For the upcoming 2025-2026 season, flu vaccines are shifting from four-strain formulas to three-strain (trivalent) formulas. They’ll target H1N1, H3N2, and B/Victoria lineage viruses, with updated components to better match what’s expected to circulate.
Testing Accuracy
If you visit a clinic or urgent care, you’ll likely be offered a rapid flu test. These are convenient but imperfect. Rapid tests correctly identify flu in only about 50 to 70 percent of people who actually have it, which means a negative result doesn’t necessarily rule it out. They’re much better at confirming flu when the result is positive, with accuracy above 95 percent in that direction. The FDA now requires newer rapid tests to reach at least 80 percent sensitivity, so accuracy is gradually improving.
If your doctor suspects flu despite a negative rapid test, they may order a more sensitive molecular test (PCR), which is significantly more accurate but takes longer to return results.
Treatment Options Still Work
The good news: antiviral medications remain effective against virtually all circulating flu strains this season. Resistance has not been a meaningful problem. Antivirals work best when started within 48 hours of symptom onset, so if you’re in a high-risk group (older adults, young children, pregnant women, or people with chronic health conditions), it’s worth contacting your doctor early rather than waiting it out.
For most healthy adults, flu resolves on its own within one to two weeks. Rest, fluids, and over-the-counter fever and pain relievers are the standard approach.
When You Can Return to Normal Activities
Current CDC guidance for respiratory viruses, including flu, follows a straightforward rule: stay home while you’re symptomatic, and you can return to normal activities once your symptoms are improving and you’ve been fever-free for at least 24 hours without using fever-reducing medication. For the five days after that, take added precautions like wearing a mask in crowded indoor spaces, washing your hands frequently, and keeping distance from others when possible.
If your fever or symptoms come back after you’ve resumed activities, the clock resets. Go back to staying home until you meet the same criteria again: improving symptoms plus 24 hours fever-free.
Bird Flu: Low Risk but Worth Understanding
H5N1 bird flu has been widespread in wild birds globally and has caused outbreaks in U.S. poultry flocks and dairy herds. Of the 71 human cases confirmed in the U.S. since early 2024, most were mild, and 64 were found through active monitoring of exposed workers rather than people showing up sick at hospitals. Seven cases were detected through routine flu surveillance.
The CDC currently rates the public health risk from bird flu as low. The virus does not spread from person to person, and the general population is not at risk through normal daily activities. You cannot get bird flu from properly cooked poultry or pasteurized dairy products. The concern with H5N1 is not what it’s doing now but what it could potentially do if the virus mutates to spread more easily between people, which is why public health agencies are monitoring it closely.