The already challenging season of viral infections and “super flu” is predicted to intensify, according to health experts.

Recent statistics from the CDC reveal a 56 percent increase in positive influenza tests compared to the previous week, alongside a 47 percent rise in hospitalizations due to the virus. Compared to the same period last year, there is a 50 percent increase in positive cases, with hospital admissions doubling.

Data up to December 13 indicates “very high” flu transmission levels in areas such as New York City, the state of New York, New Jersey, Rhode Island, Colorado, and Louisiana.

Experts attribute these alarming trends largely to the emergence of the new and hazardous flu strain, H3N2 subclade K. According to CDC reports, this strain is increasing across all but four states: Arkansas, Wyoming, Utah, and Hawaii.

Although symptoms like fever, cough, fatigue, and body aches remain consistent with past flu strains, medical professionals suggest that the manifestations of H3N2 subclade K are notably more severe.

Dr Neal Shipley, medical director of Northwell Health-GoHealth Urgent Care, told Daily Mail it is important to recognize the symptoms that ring alarm bells so you know when to seek expert help.

Shipley said that in children, the flu comes on suddenly and may also cause vomiting and diarrhea. He said people over the age of 65 are at the highest risk of complications, including hospitalization and death. 

‘If your symptoms worsen quickly, or you have trouble breathing, weakness, dehydration or symptoms that don’t improve after a few days, you should find your nearest urgent care,’ he added.

A surge in ‘super flu’ cases has prompted school closures and some hospitals to reintroduce masking guidelines (file photo)

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. 

Dr Ken Redcross, an internal medicine physician in New York and spokesperson for Boiron USA, told the Daily Mail: ‘Flu season typically peaks from December to February, and we’re still on the upswing. Even if this year doesn’t reach last season’s historic highs, we expect cases and hospitalizations to increase in the coming weeks.’ 

He urged Americans to seek medical care immediately if symptoms become severe or worse, including ‘especially trouble breathing, persistent chest pain, confusion, dehydration, or a high fever that doesn’t come down.’

‘In children, red flags include fast breathing, blueish lips, extreme fatigue, or fever with a rash,’ he added. 

Meanwhile, Covid strain XFG, also known as Stratus, has become that virus’ dominant variant and is growing or ‘likely growing,’ according to CDC figures, in more than two dozen states. 

Respiratory syncytial virus (RSV), which is particularly dangerous for infants and older adults, is also growing or ‘likely growing’ in at least two dozen states. 

However, norovirus, which causes violent, rib-cracking vomiting and diarrhea, is showing signs of a slight decline. 

As of December 6, the latest data available, nine percent of all norovirus tests came back positive compared to 12 percent the week before.

Frederick G Hayden, a professor at the University of Virginia School of Medicine, co-authored a paper published in JAMA last week that analyzed the latest flu data. He warned that because subclade K is a subtype of the strain that contributed to last year’s ‘severe’ flu season, this season will likely be severe as well. 

Hayden said in a university press release: ‘The 2024-25 influenza influenza season, largely due to influenza A H1N1 and H3N2 viruses, was associated with high severity across all age groups, including an exceptionally high number of pediatric deaths. 

‘Unfortunately, we are seeing the circulation of a new variant of H3N2 virus for which our vaccines may be somewhat less effective. 

‘However, available vaccines will reduce the risk of serious illness and potentially the spread of this virus.’

Influenza A, which includes subclade K and accounts for three in four flu cases, 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.

Dr Redcross also suggested handwashing and steering clear of anyone who may be sick, especially during the holidays. ‘The best way to reduce flu risk during and after the holidays is to limit exposure where possible,’ he said. 

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. 

CDC data from December 13 shows 15 percent of influenza tests came back positive that week compared to 8.4 percent the week before. The hospitalization rate has increased from 4.8 per 100,000 to 11 per 100,000.

The above CDC graph shows the gradual increase in positive influenza tests through December 13, the latest available data

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. 

As for Covid, the latest data from December 13 shows 81 percent of samples found in wastewater were from the XFG variant. 

Wastewater data, which tracks virus spread in communities, shows nationwide viral activity for Covid is ‘low’ and that the Midwest has the highest activity level as of December 13. 

RSV is also increasing in two dozen states and is ‘very high’ in Wyoming and Louisiana while being ‘high’ in Kentucky. 

RSV is a particularly dangerous infection for young children because it can cause inflammation that may block their small airways, potentially leading to death. About 58,000 to 80,000 children younger than five years old are hospitalized every year due to RSV, and 100 to 500 children die from the infection.

It spreads via respiratory droplets often from coughs and sneezes, and causes symptoms including a sore throat, runny or stuffy nose and exhaustion. In severe cases, patients can start wheezing.

The disease can also be fatal for older adults who are more prone to complications such as pneumonia.