The BA.2 variant is even more contagious than Omicron!

The original strain of SARS-CoV-2, which appeared two years ago, was qualified at the time as an extremely contagious virus. Since then, we have seen the Alpha, Beta, Delta, Gamma variants, and since early December Omicron. For a variant to take precedence over the others and become the majority, it must necessarily be more contagious than the previous one. Omicron is already ten times more contagious than the original strain. With the latter, the world thought they had reached a peak and hoped that this variant would be the last concern. It would seem that is not the case. A sub-variant of Omicron, named BA.2, already predominant in Denmark, could be even more contagious.

A variant that became the majority in a few weeks

While in France the BA.1 sub-variant of Omicron is the only one actively circulating, at least for the moment, the situation is different in Denmark. The BA.2 variant was first detected there on December 5, 2021. This variant has about 40 additional mutations compared to BA.1, which already had a large number of mutations related to variant Delta. In Denmark, the two sub-variants BA.1 and BA.2 co-existed at first. Then, in two weeks, BA.2 went from 20% of cases to 45%. Eventually, it became a majority within weeks. The speed at which the BA.2 variant has supplanted the BA.1 in this population is already proof in itself of its higher contagiousness.

A study confirms its higher contagiousness

A study from the University of Copenhagen in Denmark published on January 30, 2022 (not yet peer-reviewed) looked at the contagiousness of the BA.2 variant. The authors were interested in 8,541 cases of infections with the Omicron variant that occurred between December 20, 2021 and January 11, 2022, of which 2,122 were linked to the BA.2 variant. Among the 17,945 potential case contacts, 5,702 were contaminated in the week following contact. The infection rate of contact cases was 29% among contamination linked to the BA.1 variant and 39% among those linked to the BA.2 variant. The BA.2 subvariant is therefore 30% more contagious than BA.1.

In addition, the authors were interested in the vaccination status of infected people. Have a complete vaccination schedule, even with the booster, did not protect against BA.2 contamination. Which means that BA.2 is able toevade antibodies secondary to vaccination.

Finally, the authors looked at the vaccination status of contaminating people. The data are more reassuring: vaccinated individuals contaminated fewer patients than unvaccinated ones. In other words, if BA.2 has more risk of contaminating vaccinated persons than BA.1, a vaccinated person contaminated with BA.2 has less risk of transmitting it in turn than an unvaccinated person. Vaccination therefore helps to curb the circulation of the virus.

Variant of Omicron BA.2: what we know

Article of Stephanie LeGuillou, published on January 22, 2022

For several weeks, a sub-variant of the Omicron variant has been regularly detected in several countries including France. This was named BA.2. It would already be in the majority in India and Denmark. What do we know about this new variant?

the Omicron variant, first detected in South Africa in November 2021, is now the majority. Extremely contagious, hence its dazzling invasion, it causes less severe symptoms. The initial variant, BA.1, mutated in turn to give rise to the BA.2 variant. This phenomenon of variant mutations is known and expected; the more the virus circulates, the more the probabilities of mutations increase. The mutations of the BA.2 variant are approximately 20 in number. Half of them are at the level of the protein Spike, key to the virus entering cells and… target of vaccines.

A more contagious subvariant

Cases have been detected in several countries: in India and South Africa at the end of December 2021, then in the Philippines, Denmark, Sweden and France. Only fifteen cases have been identified in France for the moment. But not all samples are sequenced.

In Denmark, this sub-variant became the majority very quickly, in barely 10 days. Unexpectedly, it supplanted the initial BA.1 subvariant. As a reminder, the Omicron variant is already a virus extremely contagious, about 10 times more contagious than the original strain of the coronavirus that appeared in Wuhan at the end of 2019. These data therefore suggest that the BA.2 subvariant is even more contagious than the original Omicron variant subvariant of SARS-CoV-2.

A no more severe subvariant

Early data from India and Denmark suggest that this subvariant would not cause symptoms more severe than sub-variant BA.1. In update note of the scientific council dated January 20, 2022, an allusion is made to the BA.2 subtype of the Omicron variant of the coronavirus. It reads: ” the BA.1 subtype represents 90% of circulating variants, and the BA.2 subtype between 3 and 4%, especially in Africa and Asia. “While the scientific council points out the existence of several subtypes of the Omicron variant of SARS-CoV-2, it further specifies, “ all these sub-variants seem to have the same characteristics “. Moreover, at this stage, it is absolutely not possible to give information on the efficacy of vaccines on this sub-variant.

In France, it’s time to return to normal with the latest announcements from Jean Castex: end of compulsory telework, end of wearing a mask outdoors, reopening of nightclubs, end of gauges… In mid-December, we thought to have reached in France the peak of the variant Delta and be on the descent… when the Omicron variant arrived, lightning fast. Even if it is of course too early to draw conclusions as to the contagiousness and severity of the BA.2 sub-variant, let us hope that the rise in contamination in recent days is not due to the spread of the BA variant. .2.