• Long COVID symptoms include fatigue, breathlessness and ‘brain fog’.
  • A recent study led by Imperial College London suggests that 2 million people in England alone may have had long COVID.
  • COVID vaccination might help reduce long-term symptoms, early research suggests.

For millions of people around the world, the health impact of catching coronavirus extends well beyond the initial infection period.

A recent study in England suggests that more than two million adults in England - around 3.5% of the population - may have had long COVID. The Imperial College London-led REACT-2 study canvassed over half a million people in the country, and found one in 20 adults reporting persistent COVID-19 symptoms for 12 weeks or more.

The European Observatory on Health Systems and Policies, meanwhile, says a quarter of people who have had the virus experience symptoms that continue for at least a month - but one in 10 are still unwell after 12 weeks.

As more data emerges about long COVID, policy-makers and health systems around the world are being warned to brace themselves for the long-term implications of lasting symptoms.

“Our findings do paint a concerning picture of the longer-term health consequences of COVID-19, which need to be accounted for in policy and planning,” said Professor Paul Elliott, director of the REACT programme at Imperial’s School of Public Health

Here’s what we know about long COVID so far.

What is long COVID?

Long COVID is when people continue to have symptoms of COVID-19 for weeks or months after the initial illness.

Signs and symptoms of COVID-19 that last longer than 12 weeks and are not explained by an alternative diagnosis are most commonly described as long COVID.

What are the symptoms of long COVID?

Common long COVID symptoms include extreme tiredness, shortness of breath, chest pain or tightness and "brain fog" – problems with memory and concentration.

Other symptoms include difficulty sleeping, heart palpitations, dizziness and joint pain.

An analysis of 1,077 patients in the Post-hospitalisation COVID-19 study (PHOSP-COVID) in the UK found “clinically significant” symptoms of anxiety and depression in a quarter of participants.

5-20% of patients have symptoms that last for weeks.
5-20% of patients have symptoms that last for weeks.
Image: European Observatory on Health Systems and Policies: In the wake of the pandemic: preparing for Long COVID (2021)

How does long COVID affect people’s lives?

“This is a condition that can have a huge impact on people’s lives,” says Professor Martin McKee, director of research policy at the World Health Organization’s European Observatory on Health Systems and Policies.

“Many are unable to return to work or have a social life. Many have described how it affects their mental health, especially as the course of the condition is often fluctuating; just as they feel they are getting better, the symptoms return.”

Because long COVID affects people’s ability to work, it has “important economic consequences” for them, their families and for society, Professor McKee adds.

The Observatory believes action to tackle the wider consequences of Long COVID should include focusing on employment rights, sick pay policies, and access to benefits and disability support.

It also states that sufferers have reported feeling stigmatized and found themselves unable to access services: “They have struggled to have their cases taken seriously and get a diagnosis, received disjointed and siloed care, and found specialist care to be mostly inaccessible and variable across countries. There are also real problems with access to sickness and disability benefits.”

What causes long COVID?

In some patients, COVID-19 attacks many different body systems, such as the heart and blood vessels, the brain and the kidneys.

This helps to explain long COVID symptoms such as organ damage and blood clotting.

In a policy brief, In the wake of the pandemic: Preparing for Long COVID, the World Health Organization describes immune and inflammatory responses by the human body, which are designed to kill the SARS-CoV-2 virus – but are also “unintentionally harmful.”

Scientists at Manchester University in the UK have found a link between long COVID and a change in the immune system of patients, six months after they’ve been hospitalised for COVID-19.

They hope this will help them develop a tool to identify patients at risk of long COVID.

However, the development and severity of long-COVID do not appear to correlate with the nature of symptoms in the acute phase of the infection.

Who does long COVID affect?

Women and people who smoke are among those at higher risk of developing persistent COVID-19 symptoms, according to the REACT-2 researchers at Imperial College.

The same study links being overweight or obese, living in deprived areas and having been admitted to hospital to higher risk – while for Asian people, the risk is lower.

“Increasing age was also linked with having persistent symptoms, with the risk rising by 3.5% with each decade of life,” Imperial College adds.

Children and young people are also affected. Researchers at University College London studying long COVID in 11- to 17-year-olds.

How many people might be living with long COVID?

The REACT study suggests that a third of people who developed coronavirus went on to experience long COVID.

In the UK, around one million people – 1.6% of the population – were experiencing self-reported long COVID at the beginning of May, according to an estimate from the Office for National Statistics (ONS), the UK’s national statistics agency.

It started analyzing data on self-reported long COVID in April.

For 376,000 people, long COVID symptoms have lasted more than a year. This is a huge jump from the 70,000 people reporting long COVID symptoms of more than a year at the start of March 2021.

Uncertain endpoint
How long COVID-19 affects someone can change dramatically from person to person.
Image: Nature/ONS

Are there any treatments for long COVID?

A study of more than 800 people by advocacy group LongCovidSOS suggests that COVID-19 vaccination might help reduce long COVID symptoms. However the research is yet to be peer reviewed.

Support for long COVID sufferers includes how to manage and monitor their symptoms at home. This might include advice on managing breathlessness, fatigue and 'brain fog'.

They may be referred to a specialist rehabilitation service for specific symptoms. This can include physical, psychological and psychiatric support.