This study, published in Nature Communications, followed nearly 1,000 people. She is the first to trace the precise history of several symptoms associated with long Covid over a period of 1 year.
The 986 participants (median age: 48 years; 58% men; 35% with at least one comorbidity; 92% not hospitalized for Covid) were from the Compare Covid long multicentre cohort set up by the AP-HP. The inclusion criteria were: having had a SARS-CoV-2 infection confirmed by PCR and symptoms persisting for at least 2 months. They might be included in the study at any time (acute phase of the infection or a few months later). The follow-up was stopped in October 2021 (last inclusions in August 2021); the median duration of follow-up was 181 days.
The participants had to fill in an online questionnaire, every 60 days, the presence of 53 symptomsranging from dysgeusia to cardiovascular, gastrointestinal and neuropsychological symptoms, including muscle and joint pain.
First discovery: 12 months following infection, probability of always having at least one persistent symptom was 85% ! But, second observation, all the symptoms did not have the same evolution (table opposite). The researchers found three distinct trends.
- For half of the symptoms, the prevalence decreased over time : these were mainly signs such as coughthe smell disordersthe loss of appetite – marking, according to the authors, a remission of the acute phase of the infection (which can last up to 6 months).
- For regarding ten symptoms, including blurred vision, hair loss, joint and muscle pain, prevalence was increasing over time.
- The other symptoms remained stable over time: weight loss, circulatory problems, hypoesthesia, photophobia, even dyspnea…
The authors point out that these results have thus made it possible to discern, among all the manifestations commonly associated with long Covid, those which might be more linked to the sequelae of the acute disease (the prevalence of which decreases over time) from those linked to other mechanisms (immunological, psychosomatic or still unexplained).
However, the study did not have a control group, which makes it difficult to interpret a causal link between the infection and some of the signs studied – especially since most are non-specific and might be linked to comorbidities, intercurrent pathologies, or even to the consequences of other aspects of pandemic life. In addition, the study, having recruited volunteers, may overestimate the prevalence of long Covid.
As such, other work is still in progress within this Compare Covid long cohort, to identify markers (clinical, biological) of the evolution of patients: anyone still suffering from a long Covid (that the infection with SARS-CoV-2 has been confirmed or not) can still join the cohort via the site https://compare.aphp.fr.
