FOCUS – A new Delta sub-variant worries the United Kingdom. Called “AY.4.2”, it has been detected in most European countries. In France, 14 cases have been confirmed.
- What is this subvariant?
Identified in July 2021 by scientists, the “AY.4.2” variant is a subvariant of the highly contagious Delta which initially appeared in India and which had caused an epidemic resumption in late spring and early summer. This sub-variant is defined by two mutations at the level of the Spike protein: Y145H and A222V.
The appearance of new mutations is not surprising. “To date, 45 sublines of the Delta variant have been distinguished. The perception that these variants are homogeneous is false», Explains to Figaro François Balloux, the director of the Institute of Genetics at the University College of London. According to him, the concern of the British authorities is linked to its frequency of appearance in the United Kingdom, which has increased by 7% in recent weeks.
The AY4.2 subvariant has been detected in 27 countries and has infected 14,970 people worldwide, including 14,247 in the UK and 14 in France, according to outbreak.info figures from October 18. The cases have been identified in North America, Europe, Australia and Japan.
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- Is it more transmissible?
The emergence of this new variant raises fears of an even stronger transmissibility. “It is the first subvariant that is more transmissible than Delta. Many hoped that a maximum rate of transmissibility had been achieved with the Delta variant.», Notes François Balloux. He estimates that the rate of transmissibility could be 10% higher than the Delta.
But, according to him, this new subvariant represents a lower risk of transmission than other strains. Its emergence does not constitute “a situation comparable to the emergence of the Alpha and Delta strains, which were much more transmissible (50% or more) than all the strains in circulation at the time“. The situation “is not dramatic ” and “the slight increase in transmissibility will have little impact on the number of cases. He is unlikely to change the current situationHe adds.
- Does it affect people who have been vaccinated?
Despite its higher rate of transmissibility, “there is little reason to believe that the subvariant affects people who have been vaccinated», Reassures François Balloux. Studies are underway to determine its resistance to the vaccine.