NEW VARIANT. The BA.2 variant (sub-variant of Omicron) is predominant. It accounts for 73% of Covid cases in France and 66% globally. But BA.2 reinfections after BA.1 infection are rare. What are its symptoms? Is it possible to be re-infected? Is it more dangerous?
[Mis à jour le 28 mars 2022 à 12h36] BA.2 is a subvariant of Omicron, itself a variant of Covid-19. It is more contagious than was the BA1 Omicron sub-variant which was circulating so far in France. “The transmissibility of BA.2 raises the question of its role in reversing epidemiological trends in recent weeks, marked by a incidence rebound” warns Public health France in its risk analysis on emerging variants updated on March 25. “However BA.2 alone cannot explain these trends” qualifies the organization which puts forward the reduction of barrier gestures in France (abandonment of the mask…). The sub-lineage BA.2 is majority in Francerepresenting 73% of coronavirus cases.A BA.2 infection can occur after a first BA.1 infection but “if BA.2 reinfections after BA.1 infection have been detected, they remain rare“said the health agency. On a global scale, it is today the most frequent variant with 66% Covid sequences. What is this new mutation? of Covid-19? Is she more contagious, more dangerous, what Omicron? the vaccine effective against this new variant? What are the symptoms of BA.2 ? Update.
Definition: what is the new BA.2 variant?
“The BA.2 is a subvariant of Omicron. It is a “little cousin” of the Omicron variant“explained Jean-François Delfraissy, president of the Covid Scientific Council, at the microphone of France info in January. Named BA.2, it is a sub-lineage of Omicron like BA.1 (which circulated until now) or BA.3. “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 conducted by the research institute Statens Serum Institut (Copenhagen) announced in January 2022 that “the initial analysis does not show no difference in hospitalizations for BA.2 compared to BA.1″. However BA.2 “is the most contagious variant of the SARS-CoV-2 virus we have seen so far“, alerted Maria Van Kerkhove of the WHO, on March 19 at a press conference.
What is the rate of the BA.2 variant in France?
The BA.2 Omicron variant is now more present than the BA.1 variant, which has been circulating mainly since the end of 2021 in France. As of March 24, according to Public Health France, BA.2 represents 73% Omicron sequences analyzed over the week of March 14 to 20. “The progression of BA.2 to the detriment of BA.1 is observed on the whole of the metropolitan territory, but at different levels depending on the region. In the DROMs, BA.2 also seems to be increasing but the data needs to be consolidated“adds the organization.
What are the symptoms of the BA.2 variant?
For the moment, there are no specific symptoms listed on the cases of sub-variants BA.2. 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 a lower severity (risk of hospitalization and admission to intensive care up to 80% lower)” reported Public Health France January 26. Symptoms of the BA.2 variant (like Omicron in general) can be:
- Tiredness ;
- Cough ;
- Fever ;
- Headache
- muscle aches or body aches;
- Sore throat ;
- Runny nose ;
- Nausea and vomiting
- Unpleasant breathing (more rarely)
- Loss of taste and smell (more rarely)
Is the BA.2 variant more contagious than Omicron?
“BA.2 is more transmissible than BA.1 (Secondary attack rate of 39% for BA.2 against 29% for BA.1). A study also estimates that the generation interval (time between two cases) of BA.2 is 15% lower than that of BA.1. These differences in transmissibility explain the rprogressive placement of BA.1 by BA.2 observed globally” emphasizes Public Health France on March 25. BA.2 “is the most contagious variant of the SARS-CoV-2 virus we have seen so far“, said Maria Van Kerkhove, epidemiologist at WHO, on March 19.
Is it possible to be re-infected with BA.2 after Omicron?
A BA.2 infection can occur after a first BA.1 infection but “if BA.2 reinfections after BA.1 infection have been detected, they remain rare“underlines Santé Publique France on March 25. The duration of immunity may 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 the even more contagious BA.2. 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?
“Omicron’s BA2 subvariant does not “cause a more severe form” of Covid than BA1, according to Maria Van Kerkhove, epidemiologist in charge of the emerging diseases unit at the WHO, on March 19. However, with a large number of cases, you will see an increase in hospitalizations and this will turn into an increase in deaths.…”. She specified that there is no not “difference in terms of severity between BA1 and BA2“.
“In France, the screening strategy can detect all Omicron without distinction, whether they are BA.1 or BA.2 and therefore to know in a reactive way the level of circulation of the variant” indicates Public Health France. In a second time, a sequencing makes it possible to make the difference between the sub-variants, BA.1 and BA.2 “Screening makes it possible to reactively follow the Omicron as a whole and sequencing allows a finer analysis of the different sub-lineages [BA.1 ou BA.2]“.
Are vaccines effective against the BA.2 variant?
“The efficacy of the vaccine against symptomatic disease caused by BA.1 and BA.2 is similar: after two doses the efficacy is 10% for BA.1 and 18% for BA.2, after three doses the efficacy against symptomatic disease is 69% for BA.1 and 74% for BA.2 Efficacy drops to almost 50% two and a half months after the 3rd dose for BA.1 and BA.2“according to the latest study from the British health agency.”This suggests that vaccination is at least as effective in preventing acquisition of BA.2 and may be more effective in preventing transmission of BA.2 than BA.1“, remarked the WHO.”I‘vaccine efficacy is maintained against Omicron after administration of a booster dose, especially against severe forms“confirmed Public Health France on January 26.
Sources:
– “SARS-CoV-2 variants of concern and variants under investigation in England”, British Health Agency, 25 February 2022
– “Coronavirus: circulation of SARS-CoV-2 variants’, updated on February 25, 2022, Public Health France
-“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.