Long Covid more common than ‘long flu’, study suggests

People who get flu could have prolonged symptoms which are similar to those seen in some patients with long Covid, a new study suggests.

But lasting symptoms occur to a lesser extent among those who have had a bout of flu, academics said.

The study examined how many patients experienced long-lasting symptoms after having Covid-19 and other contributing factors – such as whether different age groups or genders are affected more.

Researchers, led by academics from the University of Oxford and the National Institute for Health Research (NIHR), also set out to see whether they could draw any comparisons with flu.

“We found in a cohort of patients with influenza that the same symptoms also tend to occur, but they tend to occur at lower rates,” said NIHR academic clinical fellow Dr Max Taquet, who led the analysis.

The team estimated that symptoms linked to long Covid were around 50% more common among those who had a Covid-19 infection compared to those who had flu.

The study, which analysed health records of more than 273,000 people who had Covid-19 and 114,000 who had flu in the US, outlined nine long Covid symptoms and the proportion of people who were suffering between 90 and 180 days after initial infection:

– Abnormal breathing – 8%

– Abdominal symptoms – 8%

– Anxiety/depression – 15%

– Chest/throat pain – 6%

– Cognitive problems such as ‘brain fog’ – 4%

– Fatigue – 6%

– Headache – 5%

– Muscle pain – 1.5%

– Other pain – 7%

All nine symptoms were more frequently reported after Covid-19 than after influenza.

The analysis found that around 30% of people who had flu experienced some sort of symptoms three to six months later compared to around 42% of those who had Covid-19.

When looking solely at Covid-19, the researchers also found that different groups were affected by long-lasting symptoms in different ways.

For instance older people and men had more breathing difficulties and cognitive problems, whereas young people and women had more headaches, abdominal symptoms and anxiety or depression.

Patients admitted to hospital were more likely to suffer cognitive problems like brain fog and fatigue compared to people who did not need to be admitted, and people who did not need hospital care were more likely to have headaches than those who needed to be admitted.

When taking all factors into account, the research team estimated that 37% of people who had a Covid-19 infection had at least one long Covid symptom three to six months after infection.

But the authors stressed there were “important caveats” which meant the results might not be generalised – namely that people included in the study with both flu and Covid could have been “iller” than those in the general population because they had sought medical help for their symptoms.

Dr Taquet said: “Over one third of patients were diagnosed with at least one of the long Covid symptoms between three and six months after their Covid-19 illness.

“The severity of the illness, age and sex affected the incidence and profile of long Covid symptoms.

“Similar symptoms were seen in people after influenza but they occur and co-occur less commonly.”

Health officials have warned that this year’s flu season could be particularly troublesome as immunity to influenza viruses waned during the pandemic.

The UK Government is hoping that more people than ever will get their flu jab, with over-50s and clinically vulnerable people being called forward to get a vaccine.

Professor Paul Harrison, who headed the study which has been published in the journal PLOS Medicine, from the Department of Psychiatry at the University of Oxford, said: “There are various post-viral conditions recognised and many of us who have experienced flu know how you don’t always feel completely better as quickly as you’ve been hoping or expecting to.”

The Office for National Statistics estimates that 970,000 British people are suffering ongoing symptoms after a Covid-19 infection.

The figures, based on self-reported symptoms, also suggest 384,000 people are still living with symptoms a year after infection.

Separate ONS estimates, based on data from participants of the Coronavirus Infection Survey who had a lab-confirmed case of Covid-19, suggest that between 3% and 12% of people have symptoms 12 weeks after infection.