A formidable new strain of flu, often referred to as a ‘super flu,’ is rapidly spreading across the United States. This potent strain is causing severe symptoms that leave many patients struggling to breathe, with some requiring mechanical assistance to do so.

Tragically, at least nine children have succumbed to the flu this year, according to official reports. Experts anticipate that more flu-related deaths will be reported as the season progresses.

The latest data from the Centers for Disease Control and Prevention (CDC) reveals that nearly every state in the US is experiencing ‘high’ or ‘very high’ flu activity. Hospital admissions have soared, marking a 54 percent increase compared to the previous week.

During the week of December 27, the most recent data available, one out of every three flu tests returned a positive result. This marks an increase from one in four the week prior and represents a 76 percent rise compared to the same period last year.

The surge in flu cases is largely attributed to a novel strain of H3N2, known as subclade K. This strain is particularly adept at evading the immune defenses that protected against earlier variants.

Medical professionals report that the infection typically begins with a notably high fever. This is followed by a persistent, phlegmy cough and overwhelming fatigue.

Dr Mark Loafman, a family doctor at Cook County Health in Illinois, warned there had been ‘more fever with the flu this year than people are accustomed to,’ which can last for five to seven days.

He added: ‘And that’s worrisome. You feel ill, you feel sick, and you worry that you’re not getting better.’

Pictured above is Sarah Lopez, 2, who was hospitalized and had to be placed on a feeding tube and ventilator after she caught the flu

Dr Juanita Mora, national spokesperson for the American Lung Association, told NBC Chicago that the fevers may not always respond to usual over-the-counter treatments such as Tylenol and Ibuprofen.

She said in a statement: ‘This new strain has symptoms of really high fevers. It has a really bad cough that won’t go away, very phlegmy, and also vomiting and diarrhea and lots of joint aches as well as muscle aches.’

In serious cases, doctors warn that the symptoms can also leave patients struggling to breathe and needing a ventilator.

In one case, two-year-old Sarah Lopez from north Georgia has been hospitalized for weeks after she was infected with the flu.

Her mother Kenia, told WSB-TV 2: ‘When I would say come here, she wouldn’t do it either. She would just throw her upper torso.

‘Overnight, everything got worse. She couldn’t sit up on her own, she couldn’t talk, she couldn’t move pretty much anything, just her head a little bit.’

Lopez was hospitalized with the flu, but then developed transverse myelitis, a rare condition where a patient suffers from inflammation in part of the spinal cord. Symptoms include back pain, difficulty moving and temporary paralysis.

At the hospital, doctors put her on a ventilator to help her breathe and a feeding tube to give her nutrients. 

Lopez pictured above before her admission to the hospital. The family is fundraising to cover the costs of her care

Speaking on Wednesday, her mother said that Lopez has now recuperated some strength and movement in her legs, but still struggles to stand up. 

She has been taken off the ventilator, and the hospital is now considering transferring her to a rehabilitation unit.

Her parents, who are caring for six other children, have been unable to work during this time. The family is asking for help to raise $11,000 to cover medical expenses. 

It was not clear whether Lopez had received the flu vaccine. She tested positive for influenza A, the same type that includes the subclade K variant.

Of the nine child deaths, four have been reported in Massachusetts and one in Illinois. It is not clear where the others took place.

Overall, officials estimate there have been at least 11million illnesses, 120,000 hospitalizations and 5,000 deaths from flu so far this year.

For comparison, at the same time last year, the CDC estimated there had been 5.3million illnesses, 63,000 hospitalizations and 2,700 deaths. There had also been 11 deaths among children. 

Other statistics show the number of visits to the doctor for flu-like illness is already at its highest level in 25 years, since 1997 -1998.

In the week to December 27, a total of 8.2 percent of outpatient visits were due to flu-like illness. For comparison, last year, which was also a bad flu season, this figure did not exceed 7.8 percent. 

Noah Smothers is pictured here in the center. He died last month from influenza-related complications at just 14 years old

Dr Caitlin Rivers, an epidemiologist at Johns Hopkins, told CNN: ‘This is definitely a banner year [for flu].

‘It’s the worst we’ve had in at least 20 years. We’re seeing a majority of the country is experiencing very high levels of activity, and we’re still in the thick of it.’

Experts have been urging people to quickly get vaccinated against the flu to slash their risk of a serious illness, particularly over-65s and those with weaker immune systems.

The subclade K strain only became common after the strains for this year’s flu shot were manufactured, however, suggesting the vaccine may only provide limited protection.

Public health officials normally recommend the flu vaccine to everyone aged six months or over, but this week the Trump administration said it would no longer recommend the flu shot for under-18s, saying it was a decision between parents and doctors. 

Flu seasons often do not peak until January or February, which means it is still too early to know how big this year’s flu wave will be.

Dr Robert Hopkins, the medical director of the National Foundation for Infectious Diseases, told AP:’ The fact that we’ve seen steady increases over the last several weeks without much of a decline or even a flattening would suggest to me that we’ve got the peak ahead of us.’

It follows another bad flu season last year, when the overall flu hospitalization rate was the highest since the H1N1 pandemic 15 years ago. A total of 288 child flu fatalities were also recorded.