Multiple forms of Long COVID identified for the first time
13.09.2022 10:41
A consortium of Luxembourgish research institutes studying the country's population has identified factors contributing to differences in the severity of COVID-19 and its associated symptoms. Their study demonstrated that individuals who experienced moderate to severe cases of acute COVID-19 infection are more likely, after 12 months, to experience a higher frequency and burden of symptoms that significantly impact their quality of life. Furthermore, the researchers were able to identify, for the first time, various subcategories of Long COVID, indicating that it is not a single disease, as previously thought.
COVID-19 infection manifests itself through a wide variety of symptoms that differ in type and intensity, consequently leading to very different effects on affected patients. One factor that has become increasingly apparent in the last year is the occurrence of persistent symptoms after the initial acute infection, commonly referred to as "Long COVID." Although this is now a known possible consequence of COVID-19, little is still known about this debilitating illness, leaving researchers with many unanswered questions.
The „CoVaLux“ study (COVID-19, Vaccination & long-term health consequences of COVID-19 in Luxembourg) is coordinated by Research Luxembourg and a consortium of Luxembourgish research institutions, including the Luxembourg Institute of Health (LIH). Ultimately, this unique project delivers important results that contribute to a better understanding of the long-term effects of COVID-19, while simultaneously leading to improved patient care.
In an initial published study led by Dr. Guy Fagherazzi, Director of the Department of Precision Health at LIH, the consortium investigated the relationship between the severity of the initial COVID-19 infection and the frequency and severity of symptoms in patients 12 months later. This research group hoped to gain a clearer understanding of the nature of Long COVID, thereby filling crucial gaps in our knowledge and ultimately contributing to predicting its consequences and learning more about the disease in general.
„A growing number of studies are reporting on long-term health consequences in patients who have recovered from a COVID-19 infection. Therefore, the identification of predictive markers and risk factors for the long-term effects of COVID-19 has been defined as a research focus. Our hypothesis is that the symptoms of Long COVID may differ depending on the severity of the initial COVID-19 illness and that the symptoms may accumulate, thus leading to the development of subtypes of Long COVID,“ explains Dr. Fagherazzi.
Of the 289 adult participants who fully completed a questionnaire over a 12-month period, nearly 60 reported at least one symptom, with an average of six symptoms. These ranged from the well-known fatigue and shortness of breath to less common problems such as memory loss and gastrointestinal issues. Given that more than 580 million cases of COVID-19 have been diagnosed worldwide to date, this suggests that a significant number of people may be affected by Long COVID in some form.
Regarding the impact of initial disease severity, it was found that volunteers who experienced an initial moderate or severe COVID-19 infection were more than twice as likely to suffer from long COVID symptoms after one year compared to those who had mild or no symptoms at the start. Furthermore, those with moderate to severe illness had an average of six more symptoms than those who were initially asymptomatic. These findings suggest that long COVID and its severity are closely related to the course of the initial infection, with a severe case of COVID-19 significantly increasing the likelihood of more and longer-lasting symptoms.
Another notable finding of the study was the recognizable patterns in the participants' symptoms, suggesting that Long COVID likely comprises several subcategories rather than a single disease. The clustering of symptoms in individuals provided insight into the nature of these subcategories. For example, loss of taste and smell appears to be characteristic of one type of Long COVID, while another is probably better described by gastrointestinal symptoms such as nausea, diarrhea, heartburn, and other abdominal pain. This information could be extremely useful as researchers seek to better define the disease and search for effective therapies.
„Our study provides a detailed description of the symptoms that appear 12 months after a COVID-19 infection and reveals a significant burden for people living with long COVID. With this work, we contribute to describing long COVID and confirming that it is a multisystem disease associated with various symptom clusters. These findings will ultimately help to better identify long COVID in clinical settings and define precision medicine strategies to improve the care of people with long COVID,“ summarizes the study’s lead author, Aurélie Fischer, scientific coordinator in the LIH research unit for Deep Digital Phenotyping.
The study was published on August 5, 2022 in Open Forum Infectious Diseases (OFID), a peer-reviewed, open-access journal dedicated to the interface of biomedical science and clinical practice, under the full title „Long COVID Symptomatology After 12 Months and Its Impact on Quality of Life According to Initial Coronavirus Disease 2019 Disease Severity“ (DOI: 10.1093/OFID-ofac-397).