different symptoms depending on the variant involved

Lisbon, Portugal — The persistent symptoms observed during a “long Covid” appear different depending on the type of SARS-CoV2 variant causing the infection, according to an Italian study, the results of which were presented at the ECCMID 2022 congress ( European Congress of Clinical Microbiology and Infectious Diseases) [1]. These differences mainly concern neurological and neurosensory symptoms.

In patients still showing symptoms more than a month after infection, those infected in 2021, when the alpha variant of the coronavirus becomes predominant, more often report muscle aches, insomnia, brain fog and anxiety, than those infected in 2020 with the original viral strain. On the other hand, they are much less affected by the loss of taste and smell.

We found no differences in cardiovascular or respiratory symptoms

“These differences can be observed on the neurological, neurosensory or psychological level. We did not find any differences regarding cardiovascular or respiratory symptoms,” commented lead study author Dr. Michele Spinicci (Department of Clinical and Experimental Medicine, University of Florence, Italy), during his presentation.

A still poorly understood post-Covid syndrome

After an infection with SARS-CoV2, the signs of the disease disappear, in most cases, in two to three weeks. Nevertheless, in some people, the symptoms may persist or reappear. When they persist beyond three months, we speak of post-Covid syndrome or, more commonly, of “long Covid”.

According to the World Health Organization (WHO), 25% of people with Covid-19 still have symptoms more than a month after infection. At least 10% have a “long Covid” with symptoms persisting for more than three months. The main risk factors are the initial severity, the number of symptoms present in the acute phase and female sex.

The most frequently reported symptoms of “long covid” are intense fatigue, post-effort discomfort, cognitive (lack of concentration, memory loss, etc.), sensory (buzzing, dizziness, etc.) disorders, but also headaches, breathing difficulties, persistent cough or even digestive disorders, sleep, irritability.

Vagus nerve dysfunction involved?

Damage to the vagus nerve during infection with SARS-CoV2 could explain the persistence of certain symptoms. This is suggested by a small Spanish study, also presented during this ECCMID session dedicated to post-Covid syndrome. [2].

In this study, researchers assessed the structure and function of the vagus nerve through various examinations in patients who developed Covid-19 with or without persistent symptoms. Ultrasound examinations revealed hyperechogenicity and thickening of the vagus nerve, signs of an alteration, in patients with long Covid. In addition, they more frequently present with swallowing disorders and a loss of mobility of the diaphragm.

“Our results suggest that vagus nerve dysfunction is a major pathophysiological feature of post-Covid syndrome,” commented Dr. Gemma Lladós (University Hospital Germans Trias i Pujol, Badalona, ​​Spain), one of the study authors. , during his presentation. The results will need to be confirmed in other studies, however, she added.

the long Covid remains poorly understood

Despite the proliferation of work on the subject, “the long Covid remains poorly understood”, commented Dr Spinicci. The very definition of post-covid syndrome is still debated. “Data on the pathophysiology are lacking and the clinical manifestations are not yet well characterized”.

In order to learn more about this post-Covid syndrome, the infectious disease specialist and his team conducted a retrospective observational study on patients hospitalized for Covid-19. They thus included 428 patients (59% men) treated on an outpatient basis at the Careggi University Hospital, in Florence (Italy), between June 2020 and June 2021. They were on average 64 years old.

Between 4 and 12 weeks after their discharge from hospital, they were asked to attend a follow-up consultation during which they answered a questionnaire to assess the possible presence of persistent symptoms. The researchers, in parallel, took up the data concerning their medical history and the clinical evolution of Covid-19.

Mainly shortness of breath and chronic fatigue

The results show that, after a median time of 53 days post-hospitalization, more than three-quarters of the patients reported at least one persistent symptom. They complained mostly of shortness of breath (37% of patients), chronic fatigue (36%), sleep disturbances (16%), visual problems (13%), a feeling of having the brain foggy (13%) and persistent cough (11%).

The analysis of medical data made it possible to highlight risk factors. Patients who have developed a severe form of the disease requiring the prescription of an immunosuppressant, such as tocilizumab, have a six times higher risk of having persistent symptoms. Those who have been put on oxygen have a 40% increased risk.

In addition to the severity of Covid-19, there is the risk factor linked to gender, since women are found to be twice as likely to report post-Covid symptoms as men. On the other hand, surprisingly, patients with type 2 diabetes appear less at risk of developing persistent symptoms (60% reduction in risk), which should be the subject of more in-depth studies, believe the authors.

By distinguishing patients infected between March and December 2020, when the original strain of SARS-Co2 was predominant, and those infected between January and April 2021, once the alpha variant had become the majority, the researchers were able to observe significant differences for some persistent symptoms reported.

Less dysgeusia and anosmia with the alpha variant

If the rate of symptoms appears similar between the two groups, cognitive disorders described as a mental fog (difficulty concentrating, forgetfulness, etc.) are more frequently reported by patients infected with the alpha variant (16% vs 10% in those infected in 2020). Similarly, they are more likely to complain of myalgia (10% vs 4%) and anxiety or depression (13% vs 6%).

Conversely, loss of smell (anosmia) was less often reported (2% vs 12%), as was taste alteration (dysgeusia) (4% vs 11%).

The authors specify that the study is observational and that, therefore, the causal relationship concerning the impact of the variants on the symptoms cannot be established. In addition, infection with the alpha variant or with the original virus strain has not been established, but only suspected.

SARS-CoV2 variants appear to induce different long Covid phenotypes.

“Variants of SARS-CoV2 seem to induce different long Covid phenotypes. Other studies must be carried out to better understand the influence of the variants, but also the impact of vaccination against Covid-19, on the evolution of symptoms”, concluded Dr Spinicci.

Questioned at the end of the session on the interpretation of the increased risk of anxiety and depression observed in patients infected in 2021, the researcher acknowledged that it could also be a consequence of the stress linked to an epidemiological situation. extended period and associated restrictions.

Spinicci M, A post-COVID syndrome: a never-ending story, SARS-CoV-2 variants may induce different long COVID phenotypes, ESCMID 2022, présentation du 23 avril 2022, Lisbonne, Portugal.

Llados G, A post-COVID syndrome: a never-ending story, Vagus nerve dysfunction in post-COVID-19 condition, ESCMID 2022, présentation du 23 avril 2022, Lisbonne, Portugal.

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