For most people, Covid-19 is a short and mild illness, but some struggle for months with symptoms, including persistent fatigue, persistent pain and breathlessness.
The condition known as “long Covid” is having a debilitating effect on people’s lives, and stories of being left exhausted even after a short walk are now common.
So far, the focus has been on saving lives during the pandemic, but there is now a growing recognition that people are facing long-term consequences of Covid infection.
And yet, even basic questions – like why people take so long to get Covid or whether everyone will fully recover – are riddled with uncertainty.
What is long Covid?
There is no medical definition or list of symptoms that all patients share – two people with long-term Covid can have very different experiences.
However, the most common feature is fatigue.
Other symptoms include: shortness of breath, persistent cough, joint pain, muscle pain, hearing and vision problems, headaches, loss of smell and taste, as well as damage to the heart, lungs, kidneys and intestines.
Mental health problems including depression, anxiety and difficulty thinking clearly have been reported.
It can completely destroy people’s quality of life.
Long Covid doesn’t just occur in people who need time to recover from intensive care. Even people with relatively mild infections can be left with lasting and serious health problems.
“There’s no doubt that Covid is around for a long time,” Prof David Strain of the University of Exeter, who is already seeing patients with long Covid at his chronic fatigue syndrome clinic, told the BBC.
How many people get that?
A study of 143 people at Rome’s largest hospital, published in the Journal of the American Medical Association, followed hospital patients after they were discharged.
It showed that 87% had at least one symptom almost two months later, and more than half still had fatigue.
However, such studies only focus on the minority of people who end up needing hospital treatment.
The Covid Symptom Tracker app, used by around four million people in the UK, found that 12% of people still had symptoms after 30 days. Recent, unpublished data suggests that as many as one in 50 (2%) of all those infected have long-term symptoms of Covid after 90 days.
Do you need severe covid virus to get long Covid?
It seems not.
Half of the people in the Dublin study still had fatigue 10 weeks after contracting the coronavirus. A third were physically unable to return to work.
Most importantly, doctors found no link between the severity of the infection and fatigue.
However, extreme exhaustion is only one symptom of a long Covid.
Professor Chris Brightling from the University of Leicester and principal investigator on the PHOSP-Covid project, which tracks people’s recovery, believes that people who develop pneumonia may have more problems due to lung damage.
How does the virus cause long Covid?
There are many ideas, but there are no final answers.
The virus may have been cleared from most of the body, but it still lingers in small pockets.
“If there is long-term diarrhoea, you will find the virus in the gut, if there is loss of smell, it is in the nerves – so that could be a problem,” says Prof. Tim Spector of King’s College London.
The coronavirus can directly infect a wide range of cells in the body and trigger an overactive immune response that also causes damage throughout the body.
One thought is that the immune system does not return to normal after Covid and this causes ill health.
The infection can also change the way people’s organs work. This is most obvious in the lungs if they become scarred – long-term problems have been seen after infection with Sars or Mers, which are both types of coronavirus.
But Covid can also change people’s metabolism. There have been cases of people struggling to control their blood sugar after developing diabetes as a result of Covid, and Sars has led to changes in the way the body processes fat for at least 12 years.
There are early signs of changes in brain structure, but these are still being investigated. And Covid-19 also does strange things to the blood, including abnormal clotting and damaging the network of tubes that carry blood around the body.
Prof Strain told the BBC: “The theory I’m working on is premature ageing of the small blood vessels that deliver oxygen and nutrients to the tissues.” But he warned that until we understand what causes it, long Covid “it is difficult to grasp the treatments”.
Is this unusual?
Post-viral fatigue or post-viral cough is well-documented and common – we’ve probably all had an infection that took many years to fully recover from.
About one in ten people with glandular fever experience fatigue that lasts for months. And there have even been suggestions that influenza, especially after the 1918 pandemic, may be linked to Parkinson’s symptoms.
“With Covid, there seem to be more far-reaching symptoms and the number of people seems to be much higher,” says Prof. Brightling.
The emphasis is on the word “seems,” though, because until we get a true picture of how many people are infected, we won’t know exactly how common those symptoms are, he says.
He told the BBC: “It appears that the uniqueness of the way the virus attacks its host and the different ways it changes cells give people a more severe infection than other viruses and persistent symptoms.”
Will people make a full recovery?
The number of people with long Covid seems to be decreasing over time.
However, the virus only appeared in late 2019, before going global early this year, so long-term data is lacking.
“We deliberately sought to follow people for 25 years, I certainly hope that very few will have problems after a year, but I could be wrong,” said Prof. Brightling.
However, there are concerns that even if people now appear to be recovering, they could face life-threatening risks.
People who have had chronic fatigue syndrome are more likely to have it again, and the worry is that future infections could cause it to get worse.
“If a long Covid follows the same pattern, I would expect some recovery, but if it only takes one more coronavirus infection to react, it could be every winter,” said Prof. Strain.
It is still possible for more problems to arise in the future.
The World Health Organization has warned that widespread inflammation caused by the coronavirus could lead to heart problems at a much younger age.
Taken and translated from BBC news
