Should we be worried about the new subvariant, the “most contagious strain since the start of the epidemic”? Marc Van Ranst’s opinion

The British government, faced with an increase in Covid-19 contamination, said on Tuesday “watch very closely” a new sub-variant spreading in the United Kingdom, although it has not been established as is if it is more contagious. This “AY4.2” variant is a sub-variant of the highly contagious Delta which initially appeared in India and which had caused a resumption of the epidemic in late spring and early summer.

The emergence of this new sub-variant despite the very strong contagiousness of the Delta, which tends to rule out new strains, however, raises fears of an even greater transmissibility.

This new sub-variant AY4.2 is almost non-existent outside the United Kingdom, apart from three cases in the United States, a few others in Denmark or even a first case recently recorded in Israel. In the latter case, it is an 11-year-old child from Europe who was a carrier of the sub-variant. He was identified at Ben-Gurion Airport in Tel Aviv and has been quarantined.

Should we be worried? Marc Van Ranst responds

Is this “AY4.2” variant likely to be the most contagious strain of coronavirus? According to the first studies, it is indeed 10 to 15% more contagious than the original delta strain. François Balloux, Managing Director of University College London Genetics Institute, spoke to the British economic newspaper Financial Times and mentioned “the most contagious strain of coronavirus since the start of the pandemic “. The expert also considers it possible that this strain will soon become a variant in its own right, with its own Greek letter attributed by scientists at the WHO.

Questioned by our colleagues from The last news, Marc Van Ranst specifies that for the moment, no trace of the AY4.2 strain has been discovered in Belgium. “At the moment, we don’t yet know what to really think about it”, he says. “This is a sub-variant within the delta variant, not yet a full-fledged variant”.

As for the possibility that this sub-variant is even more contagious, the Flemish virologist explains: Viruses strive to optimize contagiousness. For example, the alpha variant was more contagious than the original Wuhan variant. Variants that weren’t much more contagious – such as the beta variant and the gamma variant – have been completely eliminated by the delta variant. And in that delta variant, you have subtypes that will be even more contagious due to an amino acid change. If so, they will eventually prevail as well. Then gradually – if the difference is small – or more quickly – if the difference is large – they will replace the others. It is literally the law of the strongest. “

Van Ranst, who recalls that a greater contagiousness does not mean that the disease will be more severe, believes that it will be difficult to counter this new sub-variant: “The chances are slim that it is transmitted through the air or through the respiratory system. It is difficult to control this 100%. You can slow it down, but not stop it.”

The virologist remains optimistic, however, because for the moment, there is no evidence that this strain will affect the effectiveness of the vaccine. And Van Ranst concludes: “This is the hallmark of viruses, that they are constantly changing. However, most changes go nowhere. And they go away again.”

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