Covid-19: BA.4 and BA.5 sub variants threaten to re-spread the epidemic in Europe – Coronavirus



As the COVID-19 epidemic in Europe recedes and protective measures recede one by one, scientists continue to scrutinize the Omicron variant and its various sub-lineages. There is, of course, BA.1 and BA.2, responsible for the two epidemic peaks in France at the start of the year, but there are also two new ‘cousins’, BA.4 and BA.5, now on the horizon. , due to genetic differences that seem to give them an advantage. On Thursday, both were classified as “variables of concern (VOC)”, the “club” of the most problematic, by the European Center for Disease Prevention and Control (ECDC).

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12%-13% growth advantage compared to BA.2

These two viruses were first detected in South Africa in January and February. They are now dominant there, in the middle of the fall season. They have the peculiarity of presenting several mutations in the part of their genome that code for the spike protein, the “switch” that allows SARS-CoV-2 to enter our cells. In particular, the replacement L452R, which is also found in Delta.

In South Africa and Portugal, where BA.5 accounted for 37% of positive cases as of May 8, a growth advantage of 12% to 13% over the BA.2 variant was estimated. According to ECDC, this is superior to BA.4 and BA.5 Will be ”
Possibly because of its ability to evade immune protection caused by infection and/or previous vaccination, especially if this weakens over time.”

At least one case in Brittany

How can the epidemic restart in Europe? The health agency does not hide that, “The presence of these variables could lead to a significant overall increase in COVID-19 cases (…) in the coming weeks and months,” it warned, Friday, in a press release. They may even become dominant there in a few months, she suggests, while that deadline may come in Portugal. by May 22.

In France, where BA.2 is still the absolute majority, Only seven cases of BA.4 and 15 of BA.5 were identified in Region AMay 10The French Public Health Authority revealed in its weekly report issued on May 12. A number that is undoubtedly significantly underestimated compared to reality, because it was produced from “flash” sequencing probes, which are based on a limited number of positive tests. Another – indirect and incomplete – way to detect these two sub-variables, the search for the L452R mutation, is by screening tests. Proportionately, the presence of this mutation doubled during the week of May 2 to 8, compared to the previous week (from 0.4% to 0.8%).

The distribution of BA.4 and BA.5 cases by region is not reported by Public Health France, but according to our information Brittany is one of those in which at least one case has been detected. The proportion of L452R mutations is also increasing there, but it is still less than 2%. However, the data must be taken with tweezers, because our region is the region where BA.2.11, another sub-variant carrying the same mutation, is circulated in France.

European Center for Disease Control and Prevention calls for ‘vigilance’

What about the severity of BA.4 and BA.5? The first data, which are still limited, are somewhat reassuring and the CDC does not note, at this time, “there was no significant increase in the severity of infection compared to the BA.1 and BA.2 circulating lines”. However, the risk of affecting hospital services remains, if the number of coronavirus cases explodes, as happened during the two previous waves in France. However, there is good news, epidemiologists are already noticing, in South Africa, tentative signs of a slowing of the epidemic, at a level well below the level known as Omicron first.

However, the ECDC encourages countries to remain “vigilant regarding signs of emergence of BA.4 and BA.5”.

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