Forget long Covid! Now ‘long flu’ is a thing – the signs and symptoms to know
LIKE long Covid, the flu can also leave sufferers with lingering side effects, scientists say.
Covid-19 left a trail of people suffering from debilitating symptoms for months, even after they'd supposedly recovered from the infection.
Tiredness, shortness of breath, aches and pains and trouble concentrating are among top complaints.
But people hospitalised with the flu could also experience residual symptoms down the line, from Washington University School of Medicine in St. Louis and the Veterans Affairs St. Louis Health Care System suggests.
"Five years ago, it wouldn’t have occurred to me to examine the possibility of a ‘long flu'," senior author and clinical epidemiologist at Washington University, Ziyad Al-Aly, said.
"A major lesson we learned from SARS-CoV-2 is that an infection that initially was thought to only cause brief illness also can lead to chronic disease.
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"This revelation motivated us to look at long-term outcomes of Covid-19 versus flu."
The research team compared data from 81,280 people hospitalised with Covid-19 between March 2020 and June 2022 in the US to 10,985 people admitted to hospital with seasonal influenza.
Because hospital admissions for the flu fell were rare during the pandemic, researchers used data gathered from patients with the flu between October 2015 and February 2019.
Researchers followed up with participants for at least 18 months after their admissions to learn about their risks of death, hospital readmission and how the infections affected their body’s major organ systems.
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The study - published in the - found that while people hospitalised with Covid had a greater risk of dying or being readmitted to hospital, flu patients were also at risk experiencing lingering disease.
Dr Al-Aly said: “The study illustrates the high toll of death and loss of health following hospitalisation with either Covid-19 or seasonal influenza."
But he added: “It’s critical to note that the health risks were higher after the first 30 days of infection.
"Many people think they’re over Covid-19 or the flu after being discharged from the hospital.
"That may be true for some people. But our research shows that both viruses can cause long-haul illness.”
The study revealed that in the 18 months after infection, patients hospitalised for either Covid-19 or flu faced an increased risk of death, hospital readmission, and health problems in many organ systems.
They were at highest risk of this 30 days after their initial infection.
According to Dr Al-Aly: "The magnitude of long-term health loss eclipsed the problems that these patients endured in the early phase of the infection.
"Long Covid is much more of a health problem than Covid, and long flu is much more of a health problem than the flu.”
But he said the risk of long-term health effects was "substantially higher" after a Covid hospitalisation, compared to the flu.
The researchers noted that they'd only studied people who'd been admitted to hospital due to a Covid or flu infection.
"The results should not be extrapolated to those with milder infection that did not necessitate hospital admission," they said, meaning they can't predict whether people who didn't need to be hospitalised with the flu will get 'long flu' afterwards.
“Our findings highlight the continued need to reduce the risk of hospitalization for these two viruses as a way to alleviate the overall burden of health loss in populations,” Dr Al-Aly said.
“For both Covid-19 and seasonal influenza, vaccinations can help prevent severe disease and reduce the risk of hospitalisations and death."
What symptoms does 'long flu' cause?
The researchers wrote: "Our results also suggest that while both viruses exact a substantial toll of health loss across multiple organ systems."
But in analysing the long-term effects of both viruses across the body's 10 organ systems, they found some differences: while long Covid tended to affect multiple systems, long flu seamed more focused on the lungs.
As Dr Al-Aly siad: “The one notable exception is that the flu poses higher risks to the pulmonary system than Covid-19.
“This tells us the flu is truly more of a respiratory virus, like we’ve all thought for the past 100 years.
"By comparison, Covid-19 is more aggressive and indiscriminate in that it can attack the pulmonary system, but it can also strike any organ system and is more likely to cause fatal or severe conditions involving the heart, brain, kidneys and other organs.”
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Long flu patients reported symptoms like persistent shortness of breath and a cough in the 18 months following their initial infection.
It comes after experts at Queen Mary University of London said people can also experience lingering symptoms from the common cold.
Symptoms of the flu
If you have flu, you'll probably get a combination of the following symptoms quite suddenly:
- A sudden high temperature of 38C or above
- An aching body
- Feeling tired or exhausted
- A dry cough
- A sore throat
- A headache
- Difficulty sleeping
- Loss of appetite
- Diarrhoea or tummy pain
- Feeling sick and being sick