Health. How research is progressing in explaining long Covid

Health.  How research is progressing in explaining long Covid

There are some for whom Covid is not just the bad memory of a confined France, four years ago. If, every winter, we are entitled to a return of SARS-CoV-2, as it is known, for those who have contracted “long covid”, the burden is heavier.

The symptoms are varied: sometimes overwhelming physical and intellectual fatigue, breathing difficulties, shortness of breath, muscle or joint pain, digestive problems, sleep disorders, memory loss, difficulty concentrating… A disease which affects at least 2 million people according to the Inserm and which leaves the medical profession very deprived.

Finally a clue

Many teams around the world are still working on the mechanisms, diagnosis or treatment of this phenomenon. But, finally, several recent works seem to mark progress.

A study published in January in the journal Science showed significant differences in blood proteins among more than 110 patients who had Covid, including 40 with symptoms six months after initial infection. It is a “central piece of the puzzle” to explain why Covid stays in some people’s bodies for so long, said Onur Boyman, a Swiss researcher and lead author of the study.

Part of the body’s immune system – the complement system, which normally fights infections by killing infected cells – apparently remains active, continuing to attack healthy targets and causing tissue damage, these researchers say.

The team found that when people recovered from long Covid, this complement system also improved, according to Onur Boyman. “This shows that long Covid is a disease and that it is possible to measure it,” added this researcher, raising hopes for the identification of specific markers.

A “multisystemic” disease

Another recent study in patients with long Covid, published in Nature, detected abnormalities in muscle tissue and dysfunction of mitochondria – sources of energy for the cell – which could explain the great fatigue of some.

The protection of vaccines against SARS-CoV-2 against the risk of long Covid, in adults and children, has been confirmed by several recent studies.

But, for now, long Covid still remains elusive because it is “multi-systemic,” while “our minds are trained to think about diseases based on organ systems,” said Ziyad Al-Aly, a clinical epidemiologist at Washington University in St. Louis.

The causes can also be associated, or even succeed one another in the same individual, or vary depending on the person.

Understanding the mechanisms of long Covid could also help to understand “why and how acute infections cause chronic diseases”, according to Ziyad Al-Aly.

This could thus strengthen the fight against other conditions such as chronic fatigue syndrome or persistent post-flu symptoms.

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