Covid-long: 1 in 8 people retain a symptom

These symptoms include ” of the pains abdominal pain, breathing difficulties and pain, muscle aches, ageusia or a anosmia (loss of taste orsmell : editor’s note), tingling, discomfort in the throat, puffs of heat or cold, heaviness in the arms or legs as well as general fatigue “, lists this study published in The Lancet.

” In 12.7% of patients, these symptoms can be attributed to Covid-19 three to five months after infection, conclude the authors. This work, carried out in the Netherlands, is, by its scope and its methodology, an important piece for better understanding the risk of long covidi.e. the persistence of long-lasting symptoms after infection with coronavirus.

In the current state of knowledge, we know that some patients have sequels specific to a coronavirus infection and that these are not explained solely by disorders psychosomatic, as some physicians initially suggested. But the frequency of these disorders and, even more so, the physiological mechanisms by which they occur are largely unknown.

Physiological mechanisms and frequency of disorders

If the study of Lancet does not answer this second question, it makes it possible to better clarify the first element, firstly because it was carried out on a large number of patients: more than 4,000 people with Covid-19. In these patients, the episode of Covid-19 was confirmed by a PCR test where the diagnostic from a doctor.

Finally, and this is an important novelty, the responses of these patients were compared to those given by a group of people who did not have Covid-19. For it is possible to feel one of symptoms listed, without the Covid being the cause. In fact, almost 9% of people who have not had Covid have one of the symptoms previously described.

Among former Covid patients, the proportion rises to 21.4%. It is by subtraction that the researchers manage to conclude that a little more than 12% of people struck by Covid develop a sequelae specifically linked to the disease. However, this study has certain limitations, such as not having measured the frequency of other symptoms associated with long Covid, including in particular a state of depression or mental confusion.

What we know about the long Covid and the persistence of symptoms

Based on data from nearly 26,000 volunteers, scientists are still trying to understand this phenomenon of long Covid-19. In order to offer the best possible care, a study was conducted on the persistence of symptoms in people who had been infected with the SARS-CoV-2 compared to the rest of the population. The results testify to the complexity of the mechanisms that can explain the “post-Covid” state.

Inserm article, published on April 18, 2022

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 physiopathological mechanisms.

From persistent symptoms which have been most often described in the scientific literature include 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 study representative of the general population

Conducted by researchers from Inserm, Paris-Saclay University and Sorbonne University at the Pierre-Louis Institute of Epidemiology and Public Health, in collaboration with ANRS-Emerging Infectious Diseases, the new study published in journal The Lancet Regional Health – Europe 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 SARS-CoV-2 infection. This differentiates this work from most of the work that has been done on the subject, which focuses on people who have made a PCR test and who have exhibited symptoms.

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

The first group of participants included all people with a positive serological test 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.

Variability of symptoms according to serological status

From the Constances cohort, 25,910 participants answered two questionnaires during the first wave of the Covid-19 pandemic, in order to determine the presence of symptoms in the preceding fifteen days. A serological test was then carried out for each of them, between May and November 2020, in order to identify the people 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 of which people with “long Covid” complain (disorder of concentration and attention, 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 moreanosmia–dysgeusiapersistent dyspnea and fatigue than individuals seronegative for SARS-CoV-2. The other symptoms had an equivalent frequency.

Persistence of symptoms related to time of infection

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. Promote therapies and preventive approaches, such as the vaccination, which reduce symptoms during the acute phase of the disease could also have a beneficial effect on post-Covid states “, underline 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, whatever the microorganism incriminated.

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.