It has no formal definition, and there's no test to diagnose it. In fact, it has no official name. Symptoms vary widely - there one day, gone the next – baffling scientists. It can be so debilitating that even climbing a flight of stairs can put a sufferer back in bed for days. This is the phenomenon that has become known as “long haul COVID", “post-COVID syndrome” or just “long COVID”, and it is being investigated in people across the globe.

Increasing medical evidence is showing that a growing number of people who contract COVID-19 continue to grapple with a range of post-viral symptoms months after infection. Even those who may have initially experienced a relatively mild illness have reported that they continue to experience lingering symptoms. Recovery is erratic, with continuing and even new symptoms that fluctuate in intensity.

Both anecdotal reports and a growing body of research suggest persistent fatigue, breathlessness, "brain fog" and muscle aches, among other chronic problems, are affecting people for some time after their infection has cleared. Many say this prolonged illness severely impacts their lives, often leaving them unable to cope with work or enjoy everyday activities.

The World Health Organization (WHO) has reported that symptoms may linger or recur for weeks or months on end, while some patients develop medical complications that may have lasting health effects.

Although figures on how many people are afflicted by so-called long COVID are still emerging, an analysis by the COVID Symptom Study, led by King’s College London, in which millions of people in the US, UK, and Sweden are using an app to self-monitor their symptoms, found that as many as one in 10 people infected with the virus have symptoms lasting beyond one month. It is not thought that people are infectious for the long period, but just suffer long-term effects.

In the same way the virus can sometimes cause serious illness in young, otherwise healthy individuals, lingering symptoms appear to affect people of all ages, including those with no underlying health conditions.

The risk of persistent symptoms isn’t limited to those who experience severe illness when they're first infected. People who are asymptomatic or have a mild case of COVID-19 can also face prolonged illness or long-term side effects. Sometimes, these symptoms take weeks or months to appear. According to the WHO, 20% of people aged 18–34 reported prolonged symptoms.

It seems that anyone, including young people and those with no pre-existing health conditions, can develop long COVID. 

According to the British Medical Journal, figures from the UK COVID Symptom Study app showed there are a wide range of recurring symptoms experienced by patients, regardless of whether they were hospitalised, affecting the respiratory system, the brain, cardiovascular system and heart, the kidneys, the gut, the liver, and the skin. The report said these symptoms range in intensity and duration, and do not necessarily present in a linear or sequential manner.

While there is no definitive list of symptoms shared by all patients, the most commonly reported symptoms, cited in various studies, include:

·         Excessive fatigue/exhaustion

·         Breathlessness

·         Headache

·         Insomnia

·         Muscle fatigue/pains

·         Chest pain  

·         Persistent cough

·         Loss of taste and smell

·         Intermittent fevers

·         Skin rashes

·         Post-exertional malaise – when overdoing it leads to symptoms coming back

These symptoms may last for weeks or months after the body has cleared the virus. There are also additional, less common symptoms that have been reported by long COVID sufferers, which have yet to be confirmed by studies including:

·         Hearing problems

·         Cognitive issues such as “brain fog”

·         Mental-health problems

·         Hair loss 

  • For a virus that is generally associated with breathing issues and the respiratory system, COVID-19 can also cause notable damage to other vital organs. It has been linked to increased risk of blood clots, lung damage, heart damage, mental health effects, and other complications that may set people up for chronic illness.
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  • According to the Centers for Disease Control and Prevention (CDC), heart damage is the most serious potential long-term effect of the coronavirus. Imaging tests taken months after recovery from COVID-19 have shown lasting damage to the heart muscle, even in people who experienced only mild COVID symptoms. This may increase the risk of heart failure or other heart complications in the future.
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  • The type of pneumonia often associated with COVID-19 can cause long-standing damage to the tiny air sacs (alveoli) in the lungs. The resulting scar tissue can lead to long-term breathing problems.

  • The pace of scientific research on COVID-19 is unprecedented, but there’s still a lot we don’t know. Because it is a new disease, scientists are unsure about the effects months after the initial illness.
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  • Early in the pandemic, many people believed that COVID-19 was a short-term illness. In February 2020, the WHO, using preliminary data available at the time, reported the time from onset to clinical recovery for mild cases was approximately 2 weeks and that recovery took 3 to 6 weeks for patients with severe or critical disease.
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  • More recently, however, it has become clear that in some patients, debilitating symptoms persist for weeks or even months. In some of these patients, symptoms have never gone away.
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  • The phenomenon of long COVID is not unique in itself; post-viral syndrome can occur after an individual has fought off many types of viral infection, including the common cold, influenza, pneumonia, SARS, HIV, and glandular fever.
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  • Because the science is still evolving and there’s no consensus yet on a clinical definition for long COVID, much is still unknown about why the virus impacts some more severely than others, and about how it affects people over time.
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  • Research into the impact of COVID-19 is ongoing. Initiatives such as the COVID Symptom Study are tracking peoples’ symptoms and the long-term consequences of the disease via a mobile app.
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  • While some potential complications are treatable, more research is needed to develop effective treatments for other long-term side effects and symptoms of the disease.
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  • According to WHO director general Tedros Adhanom, what is clear is that “this is not just a virus that kills people. To a significant number of people, this virus poses a range of serious long-term effects.”

  • As scientists gather more data, they become better equipped to find effective treatments and management strategies.
  • If you’ve had COVID-19 and are recovering, it’s important to connect with your doctor regularly to monitor for any troubling signs or symptoms.

  • Some health organisations have developed online tools to provide people with information and guidance as they recover from COVID-19 such as the Your COVID Recovery portal from the United Kingdom’s National Health Service.
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  • Online support groups can help you understand that you not alone and provide a platform for talking through experiences. Some support groups have been involved in efforts to research long COVID include:

  • Body Politic’s COVID-19 Support Group
  • Survivor Corps, a non-profit that also run a Facebook group
  • COVID-19 Support, a Facebook group
  • If you are experiencing new or persistent symptoms following recovery from COVID-19, you should contact your doctor, who can assess the symptoms and, if needed, perform diagnostic tests to check for complications. Your doctor can also help to monitor and manage your symptoms over time.