A vaccination center in Seoul, illustration.

The effects of the vaccine on the long Covid are for the moment completely unknown.

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Kim Hong-ji / AP / SIPA

  • The World Health Organization is organizing a seminar on Tuesday around long Covid patients, some symptoms of which persist for several months.

  • A phenomenon which we know for the moment practically nothing and whose vagueness around is struggling to dissipate.

  • Why are these cases so mysterious and so little knowledge could be gathered on the subject?

Never, in the history of Humanity and Health, has so much information and information been gathered in such a short time on a virus.

A little over a year after the appearance of the coronavirus, several vaccines were discovered, the sequencing of the virus was carried out, knowledge has continued to multiply and patient care has improved markedly.

While information on Covid-19 is piling up at an unprecedented speed, a phenomenon linked to the virus remains mysterious.

Those called “long Covid”, people presenting symptoms several months after a -supposed- infection, mainly fatigue, inability to exercise and muscle pain, breathing or chest.

A veil of mystery so thick that the World Health Organization has decided to organize a seminar on Tuesday around this phenomenon, in order to find out more.

Symptoms that are difficult to objectify

At the moment, knowledge about these cases is very poor.

Long Covid cases concern 10% of people who are symptomatic of the coronavirus, having presented mild forms of the disease or even a virtual absence of symptoms, mostly women and young people.

"But we must handle these data with great caution," warns Dr. Florian Zores, who has looked into these strange cases.

There could indeed be many recruitment biases, for example, women might report symptoms more than men, who are socially encouraged to silence their pain.

The infection itself is only speculated, as in most cases people, mainly in the first wave, could not be tested - due to lack of available tests at the time.

"This makes them all the more difficult to objectify: many patients are in a way triple negative: no PCR tests, they have a negative serology (the antibodies having perhaps disappeared), and have no lesions visible by CT scan. or other ”, notes the doctor.

A viral illness or psychological symptoms?

"Nothing even indicates that it is a disease," notes the doctor Corinne Depagne, who has also looked into these cases a lot.

It does not exclude the hypothesis of symptoms that would come as a result of stress and post-traumatic shock with the health, economic and social crisis, more than resulting from a viral load.

“This does not mean that the symptoms are invented, they exist, that's for sure,” she notes.

They just aren't necessarily virological.

A few months after the SARS epidemic in Asia in the early 2000s, the same symptoms appeared.

“We can therefore exclude the thesis of a storytelling, because these symptoms were unknown to the general public.

But it can also be the result of post-traumatic shock.

"

And if the symptoms do appear after the viral load, we do not know how it would work.

Florian Zores thus presents two hypotheses: are the persistent symptoms due to the sequelae of the viral infection or is the virus still acting on the organs?

How effective for vaccines?

So many leads, vagueness and subjective data which only complicate the task even more: “Like any phenomenon presenting only symptomatic entities, without apparent lesions, there is a risk that we put a little of everything in it, post-traumatic cases, people who have lost their physical form with confinement, sick people, etc. Even today, the long term Covid undoubtedly encompasses several very different forms of illness ”, underlines Florian Zores.

Suffice to say that with all these mysteries, we do not know at all the effects of vaccines and their effectiveness on these cases.

Do they risk exacerbating a viral reaction already present, can they cure long Covid, or even prevent it for people who have not yet had it?

"No idea", concedes the doctor.

Difficult collection of knowledge

So much for everything we don't know.

The question remains: how is it that there is so little knowledge about this phenomenon, yet present in many countries?

There are several reasons for all these unknowns: first, the very principle of the long Covid is that it is ... long, so it took a long time to be listed.

The first recorded cases date from May-June, and they tended to be denied or brushed aside as it seemed incongruous.

Then, once the symptoms were really recognized, they were seen more as a consequence of confinement - with loss of muscle and motor activity - than a disease.

Finally and perhaps above all, long Covid patients are rarely hospitalized, and where applicable, show few lesions or “objective” sequelae (visible by scanner), which makes it difficult to identify them and collect data.

As such, Corinne Depagne pleads for a national strategy: “More and more centers are taking care of long Covid patients, but they tend to communicate little with each other.

However, the data on these cases should be better shared in order to try to establish factors.

"And perhaps, finally, unravel the mystery of these very strange long Covid.

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