They should become dominant in the coming months, believes the European Center for Disease Prevention and Control (ECDC).
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Make way for a new wave of Covid-19 contamination? The European Center for Disease Prevention and Control (ECDC) calls on European states to closely monitor the emergence of Omicron BA.4 and BA.5 subvariants, in a press release published on Saturday May 14. “The proportion in the European Union is currently low”clarifies the text, “but they will become dominant in the coming months”which could potentially lead to “a significant increase in the number of cases”. At this stage, the ECDC does not have any elements suggesting an increase in the severity of Covid-19 cases induced by these sub-variants compared to the previous lines.
>> Covid-19: what we know about the two new Omicron sub-variants discovered in South Africa
Consequently, the ECDC decided to transfer these two sub-variants of interest to the higher category, that of “variants of concern”. Data is still limited but BA.4 and BA.5 “seem more transmissible than the previous ones” sub-variants of Omicron, had estimated with France 24 the epidemiologist Antoine Flahault. Their Spike proteins include the mutations L452R, which increases its transmissibility, and F486V, associated with a reduction in the neutralization of antibodies.
Identified at the end of 2021, BA.4 and BA.5 are now the majority in South Africa. They could now impose themselves in Europe. “The Portuguese National Institute of Health estimated that BA.5 represented approximately 37% of positive cases as of May 8, 2022”, notes the ECDC, which adds that this sub-variant should become dominant in the country by May 22. Their competitive advantage “is probably due to their ability to evade immune protection induced by previous infection and/or vaccination, particularly if this has diminished over time”.
In France, the BA.2 subvariant of Omicron is still largely dominant, according to Public Health France (SPF), with 99% of the sequences from the latest survey. But BA.4 and BA.5 have already been detected in France and are the subject of“a enhanced surveillance”, writes the health agency in its epidemiological bulletin of May 5. SPF specified that at “May 2, 2022, two cases of BA.4 and six cases of BA.5 (had) been confirmed in France and (were) under investigation”.
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