28 April 2021: APC Microbiome Ireland, a SFI Research Centre in UCC has completed the first study to show that patients with Long COVID have significant and demonstrable disturbances in immune signalling networks, up to nine months following hospital discharge. Prof. Liam O'Mahony, a principal Investigator in the SFI Research Centre APC Microbiome Ireland, Dept of Medicine and School of Microbiology, is leading a team whose early research findings suggest that an over-active immune response may be one reason why some patients develop long-term post-COVID symptoms.  Research into the long-term persistent effects of COVID-19 in some patients (long COVID) 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. Liam O'Mahony says that through the results of this SFI funded study “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. One potential reason is that the immune system may remain in a semi-activated state for a long time following infection. 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 infection clinics who had been in-patients during the first wave of the pandemic from March to May 2020. Clinical severity ranged from mild to critical during hospitalisation and the most common symptoms at follow-up clinics were fatigue and/or difficult or laboured breathing. The data suggests that there are long-term immunological consequences following SARS-CoV-2 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. 

While the study must be replicated before any firm conclusions can be made, this data suggests that there are specific disturbances in immune signalling networks that may contribute to symptoms experienced long after clearance of SARS-CoV-2 infection. 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. 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. 

Dr. Corinna Sadlier Consultant in Infectious Diseases at Cork University Hospital says that “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. 

Given the scale of the pandemic and that up to 10% are experiencing long COVID type symptoms following primary COVID-19 infection the medical resource 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 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.