Covid long: persistent symptoms months after the first wave | Press room

Participants completed several questionnaires about their symptoms © Adobe Stock

Several months after being infected with SARS-CoV-2, symptoms persist in some patients. We are talking about a long Covid or a “post-Covid” state. Still poorly understood, this phenomenon is now carefully studied by scientists in order to enrich knowledge on the subject and to offer the best possible care.

Researchers from Inserm, Paris-Saclay University and Sorbonne University at the Institut Pierre-Louis of Epidemiology and Public Health, in collaboration with theANRS | Emerging Infectious Diseases, identified, based on data from nearly 26,000 volunteers from the Constances cohort, which persistent symptoms are most frequently reported by people who have been infected with SARS-CoV-2 compared to the rest of the population. These are mainly loss of taste or smell, difficulty breathing or fatigue. These symptoms are particularly seen in patients who had typical Covid symptoms at the time of infection. The results are published in the journal The Lancet Regional Health – Europe.

Many people report persistent symptoms several months after being infected with SARS-CoV-2. This “post-Covid” state is still poorly understood but is currently the subject of rigorous research in order to better define its prevalence in the general population and to decipher the underlying pathophysiological mechanisms.

Among the persistent symptoms that have been most often described in the scientific literature are dyspnea (difficulty breathing), asthenia (fatigue), joint and muscle pain, cognitive problems, digestive disorders, or even anosmia/ dysgeusia (loss of smell and taste).

Apart from this last symptom, these are clinical manifestations which are not specific to Covid-19 and which could, for example, be linked to other infections contracted over the same period or to more restricted access to the health system during the pandemic.

In order to better understand and better manage the “post-Covid” state, it is therefore essential for scientists to determine which persistent symptoms are more closely associated with SARS-CoV-2 infection.

A general population study

The new study published in The Lancet Regional Health looks into this question. This study first draws its originality from the fact that it was carried out in a general population cohort.

General population cohorts differ from cohorts constructed from samples of Covid patients (by definition all “symptomatic” and often with severe clinical forms or hospitalized), which are not representative of all infected people.

This type of cohort therefore makes it possible to understand public health issues by developing comparative groups, for example according to the severity of the symptoms presented at the time of infection.

The other originality of the work is that all the participants benefited from a serological test a posteriori to search for a history of infection by SARS-CoV-2. This differentiates this work from most of the work that has been done on the subject, which focuses on people who have carried out a PCR test and who have presented symptoms.

Thus, this work makes it possible to compare the persistence of symptoms seven to eight months after the first wave of the pandemic in four groups of participants[1] distributed according to the symptoms they had had during this first wave and their serological status (whether or not testifying to an infection with SARS-CoV-2).

Symptoms present in the long term according to the serological status

25,910 participants from the Constances cohort (see box) answered two questionnaires during the first wave of the Covid-19 pandemic, in order to determine the presence of symptoms in the preceding fortnight. A serological test was then carried out for each of them, between May and November 2020, in order to identify those who had been exposed to the virus.

Finally, between December 2020 and February 2021, a third questionnaire on symptoms that have persisted or persisted for at least two months was offered to participants. This questionnaire included the list of symptoms sought during the first waves of questionnaires, but also new symptoms complained of by people with “long Covid” (concentration and attention disorder, chest pain, etc.).

The researchers compared individuals who presented symptoms suggestive of an acute respiratory infection according to their serological results. They observed that people who were symptomatic and had positive serology had more persistent anosmia/dysgeusia, dyspnea and fatigue than people who were seronegative for SARS-CoV-2. The other symptoms had an equivalent frequency.

Links between symptoms presenting at the time of infection and persistent symptoms

The authors then explored the link between infection, acute symptoms and persistent symptoms. The results of their statistical analyzes show that infection with SARS-CoV-2 essentially has an effect on the persistence of symptoms if it induces certain symptoms at the time of the acute episode of infection.

“Our results confirm the importance of the clinical expression of the initial infectious episode in the risk of developing persistent symptoms. They can help guide public policies by providing more precise data on the type of persistent symptoms of Covid-19 and by encouraging the development of more effective management strategies. Promoting preventive therapies and approaches, such as vaccination, that reduce symptoms during the acute phase of the disease could also have a beneficial effect on post-Covid states”, point out the authors of the study.

These results testify to the complexity of the mechanisms that may explain the persistent symptoms, highlighting that these symptoms may be related to the virus, the initial clinical presentation of the infection and other non-specific causes.

They also suggest the importance of conducting studies on post-infectious states, regardless of the incriminated microorganism.

Further work is underway to understand the mechanisms underlying these “post-Covid” states and to quantify the proportion of these persistent symptoms attributable to SARS-CoV-2 infection.

The Constances cohort

Constances is a large French epidemiological cohort, made up of a representative sample of 220,000 adults aged 18 to 69 at inclusion. Participants are asked to take a health exam every four years and complete a questionnaire every year. The data of these volunteers are matched each year with the National Health Insurance databases. This large cohort is supported by the National Health Insurance Fund and financed by the Future Investments Programme.

The data collected concerns health, socio-professional characteristics, the use of care, biological, physiological, physical and cognitive parameters and makes it possible to learn more about the determinants of many diseases.

Constances is one of the three cohorts on which the SAPRIS-SERO project supported by Inserm and ANRS is based | Emerging Infectious Diseases, which aims to quantify the incidence of SARS-CoV-2 in the French population using serological tests.

For more information: www.constantes.fr

[1] The first group of participants included all people who tested positive for covid 19 and who reported symptoms during the first wave. In the second group, the individuals had a positive test but no symptoms. The third group were those with a negative serological test and symptoms while the fourth group was asymptomatic during the first wave, with a negative serological test.

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