The SARS – Cov – 2 was believed to be confined to the respiratory sphere and ejected from the body once the infection is completed. But according to the work carried out by the Pasteur Institute, published on July 29, 2025, the virus is much more obstinate.
By studying golden hamsters infected with different variants (Wuhan, Delta, Omicron Ba. 1), the researchers of the Pasteur Institute discovered that viral traces remained active in the brainstem up to 80 days after the infection. In other words, the virus has not only left scars, it continued to coexist with neurons in the shadows.
For scientists, this is a world premiere. Never yet the persistence of an active virus in such a strategic region of the brain has been demonstrated with so much precision.
A virus that refuses to leave the scene
Sars-Cov-2: Why is it attacking the cerebral trunk?
This region, nestled at the base of the brain, plays a vital role: it controls breathing, vigilance, balance, but also certain cognitive functions.
The fact that the virus hides is not trivial. By settling in this order center, the SARS – COV -2 could disrupt essential circuits, with concrete repercussions on mental and cognitive health of patients. This area is also more difficult to access the immune system, which would explain why the virus manages to survive it longer than expected.
When the virus turns our neurons
The analyzes carried out by the Pasteur team reveal that this prolonged presence of the SARS – COV – 2 leads to significant biological disturbances.
First observation: genes linked to dopamine, a neurotransmitter involved in memory, motivation and mood, are disrupted. Consequently, an alteration of brain metabolism which recalls certain profiles observed in neurodegenerative diseases such as Parkinson.
Second observation: the hamsters studied have developed behavioral disorders. Fatigue, anxiety, memory loss, symptoms close to depression … So many signs that echo the experience of many patients with long covid. In short, the virus is not content to be there, it acts and distinguishes.
French figures that speak for themselves
These results come to give scientific light to a reality well known to French patients. According to Public Health France, 1.8 to 2 million people still live with persistent symptoms of the COVID -19.
Among the most frequent:
These symptoms, sometimes disabling, prevent some patients from regaining a normal professional and social life.
Faced with the magnitude of the phenomenon, the Long Cavid was finally recognized as a long -term condition (ALD) in 2024, allowing patients to benefit from better financial care of their care.
What it changes for research and care
The discovery of the Institut Pasteur opens a new path to understand, and perhaps treat better, the Cavid Long. If the virus remains hidden in the brain, you have to develop tools to detect it. Researchers evoke for example the use of TEP – SCAN in FDG, an imagery that measures metabolic cerebral activity and can reveal slow or “sleep” areas.
These data could also guide the search for targeted antiviral treatments or anti -inflammatory drugs adapted to the central nervous system. The targeting objective of reducing the persistence of the virus and limiting consequences.
But the big question remains: does the phenomenon observed in hamster also occur in humans? For the moment, the clues accumulate, but the final confirmation will require in -depth clinical studies.
NAMELY
A study published in July 2025 in Nature Communications reveals that our brains have aged an average of 5.5 months during the pandemic, even in non -infected people, according to the analysis of almost 1,000 MRI by artificial intelligence.
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