Long covid symptoms include increased fatigue, lack of strength, reduced immunity, memory problems and anosmia--loss of smell. Starocean/Shutterstock

Long covid symptoms include increased fatigue, lack of strength, reduced immunity, memory problems and anosmia--loss of smell. Starocean/Shutterstock

Results of a Luxembourg study indicate that the impact of long covid on a patient’s health has strong links to the severity of the initial infection.

Even though current figures show that covid infection has slowed down significantly and most countries no longer have health restrictions in place, the impact of long covid on public health has not yet been fully understood.

Now CoVaLux (COVID-19, Vaccination & long-term health consequences of COVID-19 in Luxembourg), a research programme led by Research Luxembourg, has published its first study into the association between the severity of initial covid-19 infection, and the frequency and burden of symptoms in patients 12 months later.

Led by Dr Guy Fagherazzi, director of the department of precision health at the Luxembourg Institute of Health, the study aimed to shed more light on the nature of long covid and “fill in crucial blanks that could ultimately help to predict outcomes and uncover more about the disease,” LIH says in a press statement.

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Among the 289 adult participants who fully completed the 12-month questionnaire for the study, almost 60% reported at least one symptom with an average of 6 symptoms. These could range from the more commonly known fatigue and shortness of breath, to less well-known problems such as memory loss and gastrointestinal problems. With over 580 million cases of covid diagnosed around the world, the chances are that a significant number of people could be experiencing long covid in some form.

Multiple sub-categories

Volunteers who had experienced an initial moderate or severe infection were found to be more than twice as likely to experience long covid symptoms after one year than those who had been mild or asymptomatic at the beginning. Furthermore, moderate to severe sufferers had an average of six more symptoms than those who had been initially asymptomatic.

The study, originally published in Open Forum Infectious Diseases, a peer-reviewed open access journal dedicated to the intersection of biomedical science and clinical practice, also found patterns in the symptoms of participants, which suggests that long covid is likely made up of multiple sub-categories rather than a single disease.

By looking at how symptoms tended to cluster in individuals, it was possible to get some idea of how these sub-categories present themselves, the statement said. For example, loss of taste and smell appears to characterise one type of long covid, while another could be better described by gastrointestinal symptoms including nausea, diarrhoea, stomach burns and other abdominal pain.

“These results will ultimately help to better identify long covid in clinical settings and contribute to the definition of precision health strategies to improve the care of people with long covid,” the study’s lead author, Aurélie Fischer, scientific coordinator in the LIH’s Deep Digital Phenotyping Research Unit, says in summary,

CoVaLux is led by Research Luxembourg in cooperation with a consortium including the Luxembourg Institute of Health, the University of Luxembourg and the Luxembourg Centre for Systems Biomedicine, the Integrated Biobank of Luxembourg, the Laboratoire national de santé, the Luxembourg Institute of Socio-Economic Research, the Luxembourg Institute of Science and Technology, the Centre Hospitalier de Luxembourg, the Centre Hospitalier Neuro-Psychiatrique, the Rehazenter and Mondorf Domaine Thermal.