Syndrome could be caused by hyper-immune response
IRISH researchers have found so-called 'Long Covid' syndrome has a significant impact on the immune system for up to nine months after a patient has been discharged after hospital treatment for the virus infection.
The research - conducted as part of an historic Irish study by APC Microbiome Ireland in Cork - has hinted that the symptoms of 'Long' Covid-19 may be linked to an over-active response from the human immune system to the original coronavirus infection.
One-in-ten people who develop a serious Covid-19 infection are now believed to suffer from 'Long' Covid-19 in some form.
Many experience symptoms for between three and nine months.
APC Microbiome Ireland, which is an SFI Research Centre in University College Cork (UCC), said the study is the first to show that patients with 'Long' Covid-19 have significant and demonstrable disturbances in their immune signalling networks for months after the original infection.
The research team was led by Professor Liam O'Mahony or APC Microbiome Ireland and Prof Corinna Sadlier of Cork University Hospital (CUH).
It is hoped the study will deliver a better understanding of 'Long' Covid-19 - ranging from its symptoms to its causes and possible treatment.
'Long' Covid-19 was noted last year as long-lasting symptoms following an original coronavirus infection - ranging from lack of energy, respiratory problems, joint pain and even persistent headaches.
Some patients have experienced symptoms so severe they have been unable to work and were rendered house-bound.
"Research into the long-term persistent effects of Covid-19 is important to understand how 'Long' Covid affects daily functioning and the quality of life of these patients, and to better treat and manage these patients," Prof O'Mahony said.
“It has become apparent that there can be significant detrimental long-term effects following SARS-CoV-2 infection that impact daily functioning and quality of life, even months after the initial infection has been cleared."
"However, the reasons why some people develop these long-term symptoms are not clear."
The landmark Irish study is the first to hint that 'Long' Covid-19 may be linked to a hyper-response by the immune system to the original infection - and which continues long after the original infection had been successfully treated.
"One potential reason is that the immune system may remain in a semi-activated state for a long time following infection," he added.
"In order to test this hypothesis, we examined many of the chemical messenger molecules that are used by cells of the immune system to communicate with each other. We found that a subset of these molecules were elevated in some patients, up to nine months following hospital discharge.”
Prof. O'Mahony’s researchers collaborated with Dr Corinna Sadlier, Infectious Disease Consultant at Cork University Hospital (CUH), to follow 24 patients who attended post-Covid-19 infection clinics who had been in-patients during the first wave of the pandemic from March to May 2020.
The clinical severity of the patients ranged from mild to critical during hospitalisation and the most common symptoms at follow-up clinics were fatigue, exhaustion and/or difficult and laboured breathing.
The data suggests that there are long-term immunological consequences following Covid-19 infection, at least in those that had acute symptoms severe enough to require hospitalisation.
"The relatively low number of patients included in this study to date does not allow for researchers to perform subgroup analysis, but the findings may be of clinical value if replicated in future studies."
Further studies are required but the Irish research indicated a definite linkage for 'Long' Covid-19 to the immune system.
"The current clinical and public health priorities are designed to limit severe acute and fatal episodes of the disease, and to quickly roll out vaccines to the general population," Prof O'Mahony said.
"However we should also now determine how best to refocus some of the clinical care priorities to caring and helping those who are healing from this viral infection. Novel interventions, including dietary and microbiome supports, will need to be developed to help assist immune system recovery."
CUH Consultant in Infectious Diseases Dr. Corinna Sadlier said it was a serious issue for those recovering from Covid-19.
"Patients are experiencing an array of symptoms persisting for many months after Covid-19 infection, so-called 'Long' Covid syndrome. Symptoms are frequently debilitating and are significantly impacting quality of life for these patients," she said.
"Given the scale of the pandemic and that up to 10pc are experiencing long Covid-type symptoms following primary Covid-19 infection the medical resources required to manage these patients in the future is likely to be significant."
"Translational research such as this will be critical in understanding the mechanism underlying these ongoing symptoms from both a diagnostic and therapeutic perspective so we can optimally manage these patients in the future.”
APC Microbiome Ireland now has three other SFI-funded Covid-19 research projects currently underway that are looking at predicting the risk of developing severe Covid symptoms based on gut microbiome composition, using saliva to diagnose and monitor Covid-19 infections and developing ways to monitor Covid-19 in the air in real-time.