Symptoms of deadly ‘super flu’ sweeping the US explained…and how to tell it apart from Covid
As the cold winter weather takes hold, the US is experiencing surges of Covid and a new ‘super flu.’
The latest CDC data shows positive influenza tests are up 13 percent compared to the week before, and the amount of people hospitalized with the illness is up nearly 50 percent.
Positive tests are also up by nearly 50 percent compared to this time last year, while hospitalizations have more than doubled.
The data, which goes up to December 6, also shows ‘very high’ flu transmission in New York City, New Jersey, Colorado and Louisiana.
Experts believe the surges are largely driven by the dangerous new flu strain H3N2 subclade K, which is on the rise in more than three dozen states. This year’s dominant flu strain is brand new to people’s immune systems, making them highly vulnerable and at an increased risk of severe, hospitalizing illness.
Several schools across the country have closed for days at a time after hundreds of students came down with flu-like symptoms, and a growing number of hospitals have reintroduced mask policies for patients, visitors and doctors.
At the same time, Covid strain XFG, also known as Stratus, has become the virus’ dominant variant, causing a signature ‘razor blade’ sensation in patients’ throats.
And CDC trends data shows the spread of of both illnesses is likely to worsen in the coming weeks, with illnesses trending up in many states.
Below, the Daily Mail reveals the tell-tale symptoms of super flu and the newest Covid strain and how to tell which condition is making you sick.
A surge in ‘super flu’ cases has prompted school closures and some hospitals to reintroduce masking guidelines (file photo)
‘Super flu’
About 3 million Americans have contracted influenza A, which accounts for three in four flu cases, so far this season, and there have been 1,200 deaths.
Approximately 30,000 people have been hospitalized.
This week, the CDC reported the first child death from the flu for the 2025-2026 season, which occurred during the week ending December 11.
The agency didn’t give details on the child, but on Tuesday, Colorado health officials confirmed the state’s first influenza-associated death of a child for this season.
The CDC reports that 89 percent of influenza A samples tested since September have belonged to H3N2 subclade K.
The above CDC graph shows the increase of positive influenza tests that have been reported to the CDC up to December 6, the latest data available
Super flu’s symptoms appear to be similar to previous influenza A strains, though doctors have noted they could be more severe.
According to the CDC, symptoms include fever, cough, sore throat, runny or stuffy nose, muscle or body aches, headaches, fatigue, vomiting and diarrhea.
The flu virus’s unpredictability and rapid mutation make it unclear whether H3N2 will remain the dominant strain or become more severe.
Influenza A is contagious from about one day before symptoms appear until five to seven days after becoming sick. Symptoms typically improve within a week, though some signs like cough and fatigue can linger for more than two weeks.
Influenza A can best be prevented with an annual vaccine, which is 30 to 75 percent effective. As of late November, 40 percent of American adults have received this season’s flu shot, which is in line with last year’s figures.
Health officials also recommend regular handwashing and avoiding contact with people who have flu-like symptoms.
Flu season in the US typically runs from October through May.
Covid
The current dominant strain of Covid is XFG or Stratus, CDC data shows.
The XFG variant first emerged in the US in March. While symptoms are largely similar to previous variants, patients have noted a distinct ‘razor blade’ sensation in their throats.
Other signs are similar to the flu, including fever, chills, cough, shortness of breath, congestion, runny nose, body aches, vomiting and diarrhea. However, Covid also causes a loss of taste or smell that is distinct from the flu.
Covid is generally contagious for one to two days before symptoms appear and eight to 10 days after symptom onset.
Symptoms typically improve within a few days, though in some cases this may take two or more weeks.
The latest CDC figures, which run through December 6, show that 67 percent of all Covid samples found in wastewater were from XFG. This is down from 82 percent the prior two weeks, which could be a sign that a new variant is emerging.
Wastewater data, which tracks virus spread in communities, shows nationwide viral activity for Covid is ‘low’ and that the Northeast has the highest activity level as of December 6.
However, the data also shows the spread is worsening in nine states and is only declining in four.
Indiana is the only state where Covid wastewater activity is ‘very high.’
As of December 6, Covid test positivity is 3.6 percent, up from 3.1 percent the week before. The hospitalization rate has remained steady at 0.7 per 100,000 people.
