2023-09-22 08:00:06
At the end of 2022, Santé Publique France estimated that around 2 million French people would suffer from long Covid, the prolonged form of SARS-CoV2 infection. A significant number of symptoms are associated with long Covid. A recent study makes it possible to distinguish different forms of long Covid, not on the clinical level, but on the immune level. Explanations.
SARS-CoV2 infection and long Covid
The World Health Organization (WHO) describes the prolonged symptoms of SARS-CoV2 infection under the term of Covid long, post-acute sequelae of SARS-CoV2 infection or post-Covid-19 condition. The symptoms associated with long Covid are numerous and include:
- Disabling fatigue;
- Difficulties with memory and concentration;
- Respiratory disorders;
- Tachycardia;
- Poor regulation of blood pressure;
- Digestive, renal, reproductive, vascular and immunological disorders.
If the risk of long Covid was first associated with severe forms of the disease, studies have since shown that all infected subjects could present with prolonged forms impacting their quality of life and preventing a return to normal life. According to the studies carried out, the risk of developing long Covid after a mild to moderate form of the infection is of the order of 5 to 20%, with a greater risk for women than for men.
The immune response of patients with long Covid
In terms of pathological mechanisms, researchers do not yet know how to explain the prolonged forms of Covid. Several hypotheses have been successively put forward and are the subject of in-depth studies:
- An insufficient response of the immune system to the viral infection;
- An excessive immune response associated with inflammation;
- The persistence of the virus in certain regions of the body.
To find out more, researchers recently conducted a study to analyze the immune response of patients with long Covid.
A total of 28 seropositive patients (serological detection of antibodies against the virus) and 23 seronegative patients, having presented symptomatic infection with SARS-CoV2 (at least 3 major symptoms of infection) and having seen at least three of their symptoms persist for at least three months. Their data were compared to those of patients who were infected but did not develop long Covid and uninfected subjects.
Different origins?
In the two groups of patients with long Covid, persistent symptoms were similar, with a higher number of symptoms in HIV-negative patients. Using very sensitive assays, researchers detected low amounts of antibodies against the virus in 22.7% of seronegative long-term Covid patients. These antibodies were present in higher quantities in HIV-positive subjects. By analyzing the immune response of HIV-negative patients, the researchers showed that the immune response was defective for SARS-CoV2, while remaining preserved for other viruses.
At the same time, the immune response was normal in HIV-positive patients. These data reveal the existence of two types of immune responses associated with long Covid. HIV-positive patients exhibit immune responses similar to those of patients who have recovered from the infection, whereas HIV-negative patients have a weak and defective immune response against the virus. However, patients in both groups had similar prolonged symptoms, suggesting that long Covid could have multiple origins.
Estelle B., Doctor of Pharmacy
Sources
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