Covid-19: new study on the effectiveness of antibodies on variants

If our body reacts rather well to the British variant, the South African is much more problematic (illustration image).

© SAJJAD HUSSAIN - AFP

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A new study on the effectiveness of our immune response to variants of the coronavirus was published this Friday in the British journal

Nature Medicine

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This work by the Institut Pasteur confirms what we already knew: if our body reacts rather well to the British variant, the South African is much more problematic.

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What is the immunity of a person infected with the coronavirus several months ago if they encounter one of these variants?

To find out, the authors of the study took the serum of people cured of Covid-19 infected with the "historic" strain.

In this serum are the antibodies.

Scientists have observed their behavior against the British and South African variants.

For the first, even a serum taken 9 months after the first contamination remains just as effective, the English variant is neutralized in 95% of cases.

For the South African, however, it is more complicated.

The efficiency drops to 60% and above all it takes a lot more antibodies - 6 times more - to be able to neutralize it.

People with a weak immune response are therefore particularly at risk.

► To read also: What do we know about the different variants of Covid-19?

The researchers also wanted to determine what is the level of response provided by the vaccines, that of Pfizer in this case.

A week after the second injection, the numbers are similar: just as effective against the British variant as against the historic strain, but only 60% against the South African. 

This new study confirms the results of previous laboratory research, but goes further.

This time the authors used authentic viral strains that came closer to what is seen in real life. 

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Read also: Covid-19: the South African variant could immunize against other variants, according to a study

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