Covid: why some do not contract the virus while living with a positive person?

A scientific discovery shows that some people are protected from Covid infection thanks to cells developed after a cold.

People with colds are less likely to contract Covid than others.

In any case, this is the conclusion of a scientific study carried out by British researchers from Imperial College London who, with this discovery, demonstrate the importance of T cells in Covid infection.

A study of 52 people

The study began in September 2020 when most people in the UK had not been infected or vaccinated against Covid.

The researchers called on 52 people who lived with a person who had been infected with the covid confirmed by PCR and who had therefore been exposed to the virus.

Participants did PCR tests at first, then after 4 days and 7 days later, to determine whether or not they had developed an infection.

Blood samples from all 52 participants were taken within 1 to 6 days of exposure to the virus. This allowed the researchers to analyze the levels of pre-existing T cells.

The researchers found that there were significantly higher levels of these cross-reacting T cells in the 26 people who were not infected, compared to the 26 people who were.

The results of this research, published in Nature on Monday, January 10, could even make it possible to develop a universal vaccine thanks to this new identified factor.

A demonstrated protective role

Indeed, this study provides the demonstration of protective role T cells.

The lymphocytes developed during infection with another coronavirus such as a common cold recognize the Covid, this had been demonstrated a few months ago.

But this new study provides proof that these lymphocytes, T cells can outright protect against a Covid infection.

The basic premise of the researchers before proceeding with this study was to know why some people did not contract the Covid when they were very exposed especially when living with an infected person.

Exposure to Covid does not universally result in infection and pre-existing T cells, primed by endemic human coronaviruses, could protect people not yet infected with Covid. “

Only the vaccine protects

Attention the researchers of this study are clear on one point and made a point of clarifying it in an interview for the Imperial College of London: this is only a scientific discovery, but not a protection against the Covid.

Today, only the vaccine can protect against this infection.

Towards a universal vaccine?

Beyond a scientific explanation that may explain that some people would be more protected from an infection than others at a given time, this discovery on T cells could make it possible to design a vaccine with this data.

Scientists have shown that T cells targeted internal proteins within Covid, rather than the spike protein on the surface of the virus, the infamous Spike protein, to protect against infection

Current vaccines do not induce an immune response to these internal proteins.

Researchers claim that alongside our existing effective vaccines targeting spike proteins, these internal proteins offer a new vaccine target that could provide long-lasting protection, as T cell responses persist longer than antibody responses which decline for a few months. after vaccination.

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