The BA.2 variant is a subvariant of the Omicron variant. It remains a minority in France but on the rise: between 5 and 6% of viruses would correspond to BA.2. Is this new mutation more dangerous than Omicron? What symptoms? Can you be re-infected after contracting Omicron? All about the BA2 sub-variant.
[Mis à jour le 11 février 2022 à 11h43] BA.2 is a subvariant of Omicronitself a variant of the Sars-Cov-2 coronavirus that appeared in France at the end of 2021. BA.2 is detected at low levels in most northern European countries and from the west. “Omicron accounted for 98.8% interpretable sequences in the Flash survey week 04 of 01/24. The sub-lineage BA.2 remains a minority but on the rise (5.4% on January 24 vs 1.9% on January 17)” according to the epidemiological bulletin of Public Health France of January 10. “However, BA.2 does not seem to progress as quickly in France as observed in Denmark” indicates Public Health France. “It doesn’t seem more dangerous than the Omicron variant, it would not cause no more severe forms“ reassured Gabriel Attal during the Council of Ministers on February 2. “BA.2 is more transmissible than BA.1 but vaccinated people are less likely to become infected and transmit the infection“concluded the new Danish study from the Danish Infectious Diseases Control Authority (SSI) relayed in a communicated January 31. “On could potentially recontaminate with BA.2 even when we would have been contaminated with the Omicron variant“, explained Olivier Véran on January 25 on LCI. 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 the BA.2 sub-variant?
“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, especially within the Spike protein. “The most recent data appear to confirm that BA.1 and BA.2 show similar severity and immune response evasion, and therefore BA.2 is not considered a distinct variant but is included in the Omicron VOC.” specifies Public Health France. A danish study published on January 20, 2022 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″.
What is the rate of the BA.2 variant in France?
“The sub-lineage Omicron’s BA.2 remains a minority but growing (5.4% on January 24 vs 1.9% on January 17)” according to the epidemiological bulletin of Public Health France of January 10. “However, BA.2 does not seem to progress as quickly in France as observed in Denmark“indicates Public Health France.
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. On the other hand for the Omicron variant “epidemiological 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?
“It seems that it is even more contagious (than the Omicron variant, editor’s note), that it presents significant risks of recontamination” declared Gabriel Attal during the Council of Ministers on February 2. The Danish study of January 31 reveals “an overall secondary attack rate of 39% in households infected with BA.2vs 29% in households infected with BA.1“And to conclude”Omicron BA.2 is inherently much more transmissible than BA.1“. 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 it possible to be re-infected with BA.2 after Omicron?
“We could potentially recontaminate ourselves with BA.2 even when we have been contaminated with the Omicron variant“, explained Olivier Véran on January 25 on LCI. “If the original Omicron quickly spread, it is among other things because it can recontaminate people who already have antibodies.“, recalled epidemiologist Catherine Hill, interviewed by Le Figaro the same day. The duration of immunity may therefore depend on the variants, and especially on a new variant, which could circumvent the immunity acquired with infection with another variant. This was the case with Omicron at the end of 2021, which can partially escape protection from infection or the vaccine. And it seems that this is also the case with BA.2, even more contagious. On December 17, a Imperial College London study believed that “the risk of reinfection with the Omicron variant is 5.4 times greater than that of the Delta variant”.
Is the BA.2 variant more dangerous than Omicron?
“It seems to be more contagious, that it presents significant risks of recontamination but it doesn’t seem more dangerous than the Omicron variant, it would not cause no more severe forms“ reassured Gabriel Attal during the Council of Ministers on February 2. “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.
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 Professor Antoine Flahault, epidemiologist on BFM-TV on January 21.
What is the situation in Denmark?
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“. The situation in Denmark, where the replacement of BA.1 by BA.2 seems to coincide with a rebound in incidence, raises the question of a greater transmissibility of BA.2 compared to BA.1. “However, it is important to note that the country had lifted all the measures in September 2021 and only reintroduced some of them in mid-November 2021” emphasizes Public Health France.
Sources:
-“BA.2 is more transmissible than BA.1 but vaccinated people are less likely to become infected and to transmit the infection”, January 31, Statens Serum Institut.
– COVID-19: epidemiological update of January 27, 2022, Public Health France
– “Risk analysis on emerging variants of SARS-CoV-2”, January 26, 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.