Scientists say long-term Covid could be caused by a virus that damages the all-important vagus nerve.
- Vagus nerve damage may be responsible for some long-term Covid symptoms
- Digestive problems and heart palpitations can be caused by changes in the nerves.
- The findings suggest that vagus nerve dysfunction is a “central” feature of long-term Covid-19.
The study suggests that some of the long-term symptoms of Covid may be caused by a virus damaging a vital nerve.
Scientists believe that vagus nerve inflammation could explain the wide and seemingly unrelated range of symptoms that may plague survivors months after the disease has been overcome.
Prolonged Covid, a general term for symptoms ranging from neurological to digestive, heart and lung problems, has puzzled scientists throughout the pandemic.
The vagus nerve is the longest nerve in the body and connects vital organs including the brain, heart, lungs and intestines and controls the muscles used for swallowing. Experts describe it as the “highway” of the nervous system.
Scientists at a hospital in Spain conducted tests on 350 long-term Covid patients and asked them about their symptoms to determine if the nerve is associated with lingering health problems.
The results of their preliminary analysis, based on 20 patients, show that symptoms such as gastrointestinal problems and heart palpitations were associated with vagus nerve damage.
The researchers said their findings, not fully published or peer-reviewed, suggest that structural changes in the vagus nerve are a “central” feature of long-term Covid.
Spanish scientists said nerve inflammation caused by Covid could be responsible for long-term symptoms, including gastrointestinal problems and heart palpitations.
What is Long Covid?
As of January 2, about 1.33 million people in the UK were sick with Covid-19.
According to the ONS, prolonged Covid is an informal term used to describe ongoing symptoms following a Covid infection that last more than four weeks.
Protracted Covid has been credited with a dizzying array of symptoms, including:
- extreme tiredness (fatigue)
- chest pain or tightness
- problems with memory and concentration (“brain fog”)
- difficulty sleeping (insomnia)
- pins and needles
- joint pain
- depression and anxiety
- tinnitus, earache
- feeling unwell, diarrhea, abdominal pain, loss of appetite
- fever, cough, headaches, sore throat, changes in smell or taste
The condition is incurable, although the NHS recommends a range of treatments designed to relieve symptoms.
Coronavirus-induced blood vessel damage is also closely linked to long-term Covid.
Official estimates show that around 1.3 million Britons, 2.1 per cent of the population, have long-term Covid-like symptoms lasting at least four weeks after being infected.
But because the condition is hard to pinpoint, and the numbers are based on self-reported symptoms, it’s hard to know exactly how many people suffer from the condition.
Fatigue, shortness of breath, and loss of smell or taste are the most common ongoing symptoms.
To study the role of the vagus nerve – approximately 3 mm in diameter – in long-term Covid, doctors at the German University Hospital in Badalona recruited 348 patients.
Two-thirds of the group had symptoms similar to those with nerve damage, which usually occurs as a result of surgery, physical trauma, or a tumor.
These include diarrhea, heart palpitations, dizziness, difficulty swallowing, voice problems, and low blood pressure.
Further examinations of 22 patients also showed that just over a quarter had a thickened or inflamed vagus nerve.
Dr. Gemma Llados and Dr. Lourdes Mateu, physicians at the hospital and authors of the study, said the results show that the majority of long-term Covid patients with symptoms of vagus nerve injury had changes in their nerve structure or function.
“Our findings so far point to vagal dysfunction as a central pathophysiological feature of long-term Covid,” they added.
The results were presented at the European Congress of Clinical Microbiology and Infectious Diseases.
Dr David Strain, a senior clinical lecturer at the University of Exeter School of Medicine who was not involved in the study, said this adds to growing evidence that at least some of the long-term Covid symptoms are “mediated through direct effects on the nervous system.”
He said: “It is possible that people who are prone to nerve damage are at the greatest risk of developing long-term Covid.
“In this case, this observation tells us a little more than nerve damage from Covid, it is greater in people with long-term Covid, and the damage is easy to detect in a long, complex nerve.”
But Dr. Strain noted that not all persistent post-infection symptoms will be related to this nerve, so more research is needed into the triggers for brain fog and muscle pain.
He said drugs used to treat vagus nerve damage could be considered for long-term Covid.