The BA.2 variant, a minority in France, is a sub-variant of the Omicron variant. “We could recontaminate ourselves with BA.2 even when we would have been contaminated with the Omicron variant” warned Olivier Véran on January 25. What are the dangers of this new mutation? His symptoms? Its contagion? What is the situation in France?
[Mis à jour le 31 janvier 2022 à 19h11] BA.2 is a subvariant of Omicron, itself a variant of the Sars-Cov-2 coronavirus. In Europe, BA.2 is detected at low levels in the majority of northern and western European countries. The Omicron variants identified in France until the second week of January still belong overwhelmingly to the BA.1 sub-lineage. According to the results of the Flash surveys mentioned by Santé Publique France in its epidemiological point of January 27, “the proportion of BA.1 and BA.2 was 68% and 0.26% in S01 (4 BA.2 sequences), 94% and 1% in S02 (9 BA.2 sequences). The spread of the BA.2 sub-lineage in some countries may suggest a advantage of transmissibility compared to BA.1, but preliminary data support a similar severity. The evolution of the proportion of BA.2 and knowledge about this sub-lineage will continue to be closely monitored over the coming weeks.“.”It responds well to the vaccine with respect to the severe forms, the severe forms do not occur in people who have been vaccinated three times. And then it doesn’t seem to be more virulent. There is no description from the Danes of new symptoms” reassured Professor Antoine Flahault, epidemiologist on BFM TV January 21. Today it is majority in Denmark and India. What is this new mutation of Covid-19? Is she more contagious, more dangerous, than Omicron ? the vaccine effective against this new variant? Update on the situation.
Definition: what is sub-variant A.2?
“The BA.2 is a subvariant of Omicron. It is a “little cousin” of the Omicron variant“declared Jean-François Delfraissy, president of the Covid Scientific Council, at the microphone of France info Tuesday, January 25. Named BA.2, it is the youngest of the majority strain of this variant, called BA.1, which is the majority in Europe. The difference between BA.1 and BA.2 is significant, in particular within the Spike protein, specifies Santé Publique France. If discussions are underway to determine whether BA.2 should be considered as a different variant of BA.1, they are both currently grouped within the Omicron variant. A danish study published in January and conducted by the research institute Statens Serum Institut (Copenhagen) pointed out that “the initial analysis does not show no difference in hospitalizations for BA.2 compared to BA.1″. “Worldwide, the Omicron variant represents 94% of circulating viruses with several subtypes: BA.1, BA.2, BA.3 and those not assigned to BA.1-3 lineages. The BA.1 subtype accounts for 90% of circulating variantsand the BA.2 subtype between 3 and 4%. All of these sub-variants seem to have the same characteristics” informs the Covid Scientific Council in its Opinion of January 20.
What is the rate of the BA.2 variant in France?
The BA.2 sub-variant is present in France but remains very much in the minority. “Among the interpretable sequences of the Flash surveys, the proportion of BA.1 and BA.2 was 68% and 0.26% in week 01; 94% and 1% in week 02. Given that 5.2 million new cases of SARS-CoV-2 infections were reported between S52 and S02, the number of infections by BA.2 over this period is estimated at 9,900 vs 3.6 million for BA.1. Diffusion of the BA.2 sublineage in some countries may suggest a transmissibility advantage over BA.1, but preliminary data support similar severity“said Public Health France in its epidemiological update of January 27.
What are the symptoms of the BA.2 subvariant?
For the moment, there are no specific symptoms listed on the few cases of BA.2 sub-variants. In contrast for the Omicron variant “lEpidemiological investigations indicate a specific clinical presentation with more upper respiratory symptoms and less loss of taste and smell, as well as less severity (risk of hospitalization and admission to intensive care up to 80% lower )” reported Public Health France January 26.
Is the BA.2 variant more contagious than Omicron?
“The spread of the BA.2 sub-lineage in some countries may suggest a advantage of transmissibility compared to BA.1, but preliminary data support a similar severity” informed Professor Antoine Flahault on BFM-TV. In France, the screening strategy makes it possible to detect all Omicron cases without distinction, whether they are BA.1 or BA.2. “Secondly, the sequencing carried out within the framework of the Emergen Consortium makes it possible to follow the differentiated diffusion of these two sub-lineages” warned Public Health France.
Is the BA.2 variant more dangerous than Omicron?
“In terms of severity, preliminary data from Denmark showed a equivalent hospitalization rate between BA.1 and BA.2. Preliminary analyzes in the UK showed a higher secondary attack rate for BA.2 compared to BA.1 (13.4% vs 10.3%) but a vaccine efficacy against similar symptomatic infections for the two sublineages. Further studies are underway to more accurately assess the transmissibility, severity and immune response evasion of BA.2 compared to BA.1.” noted Public Health France. The President of the Scientific Council was more cautious, indicating that he “did not know“if this sub-variant was more dangerous.”The question is to know how serious it will be. Therefore, we look at it with great attention“, underlined Jean-François Delfraissy. According to the Danish study published in January “dare infectivity testing […] are in classincluding attempts to culture BA.2 in order to perform antibody neutralization studies“.”Very early observations in India and Denmark suggest that there is no no major difference in severity compared to BA.1“tweeted Tom Peacock, a virologist at Imperial College London, on January 19, 2022.
Are vaccines effective against the BA.2 variant?
“L’vaccine efficacy is maintained against Omicron after administration of a booster dose, especially against severe forms” confirmed Public Health France on January 26. “It responds well to the vaccine against severe forms, severe forms do not occur in triply vaccinated people“said Pr Antoine Flahault, epidemiologist on BFM-TV on January 21.”It is expected that the vaccines also have an effect against serious diseases when infected with BA.2“had estimated the Danish scientists who are continuing their analyses.
What is the situation in Denmark?
“He [le sous-variant BA.2] seems to have seized power in Denmark” indicated Jean-François Delfraissy on France Info on January 25. According to the results of the Danish study, “the BA.2 variant accounted for 20% of all cases of covid-19 in Denmark in week 52, increasing to about 45% during week 2. During the same period, the relative frequency of BA.1 has dropped“.
Sources:
– “Risk analysis on emerging variants of SARS-CoV-2”, January 26, 2022, Public Health France.
– COVID-19: epidemiological update of January 27, 2022, Public Health France
-“Now a variant of Omicron, BA.2, accounts for nearly half of all Danish Omicron cases” January 20, 2022, Statens Serum Institut.