Covid centaur variant (BA.2.75): symptoms, France, dangerousness

Covid centaur variant (BA.2.75): symptoms, France, dangerousness
Covid centaur variant (BA.2.75): symptoms, France, dangerousness

NEW COVID VARIANT. A sub-variant of the Omicron variant nicknamed Variant Centaure (official name: BA.2.75) circulates weakly in France and is prevalent in India. About sixty cases have been recorded in France. Symptoms, mutations, dangerousness, vaccine… What we know to date.

[Mis à jour le 23 septembre 2022 à 12h02] Under the radar of the health authorities: a new mutation of the Covid. Appeared in India since May 2022, the new sub-variant of BA.2itself a subvariant of Omicron, was detected in France for the first time in July 2022: it is the subvariant BA.2.75also nicknamed “centaur variant” (or “centaurus” in English) unofficially. It continues to circulate mainly in India where he is now the majority. No signal of concern has yet been associated with it. “If it seems to become the dominant strain in India – the question is whether it will become the dominant strain all over the world“, indicates Antoine Flahault, director of the Institute of global health of the University of Geneva to AFP. In France, it is detected in very low levels, with 0.3% of interpretable sequences during the Flash S36 investigation, indicates Public Health France in its bulletin of September 22, 2022. To date, it has infected about sixty people in France. He is closely monitored by health authorities, such as Public Health France or the World Health Organization (WHO). How many cases to date? Where in the world ? What specific symptoms would they cause? Would it be more dangerous than the other sub-variants? Knowledge to date.

Definition: what is the Centaur variant, sub-variant of Covid?

The BA.2.75 mutation or the V-22JUL-01 sublineage (nicknamed Centaur or Centaurus, unofficially, that is, the health authorities do not call it that) is a subvariant of BA.2, itself a subvariant of the Omicron variant of Covid. The BA.2 sub-variant was the majority in France until mid-June 2022, but was gradually replaced by the BA.5 sub-variant, indicates Public Health France. “The BA.2 is a subvariant of Omicron, who is himself a “little cousin” of the Omicron variant“explained Jean-François Delfraissy, president of the Covid Scientific Council, at the microphone of Franceinfo in January 2022.

Is the Centaur sub-variant more dangerous than the others?

The replication capacity of BA.2.75 in the lungs might be higher than that of BA.2 and BA.5.

In India, BA.2.75 has not been associated with any epidemiological or clinical signals of concernbut its characteristics remain to be determined, indicates Public Health France in its risk analysis of the variants of September 7, 2022. In coherence with previous in vitro results, an in silico study (molecular simulation model) underlines an affinity of BA.2.75 for its higher ACE2 receptor than for the other Omicron sublineages (8, 9). If the affinity to the receptor is a factor that can impact the transmissibility of a variant, it is not the only factor and these molecular results are difficult to transpose.

In terms of severitya hamster model study showed a higher replication capacity in the lungs for this sub-lineage compared to BA.2 and BA.5, which, according to the authors, could lead to greater severity. However, the hamster model is difficult to transpose to humans, and these results should be interpreted with caution.

Many mutations. According to Public Health France, the subvariant “BA.2.75 was spotted by the international community of bioinformaticians and virologists because it carries a significant number of additional mutations in the Spike protein (K147E, W152R, F157L, I210V, G257S, D339H, G446S, N460K, R493Q reversion…). Nowadays, no data indicating that BA.2.75 possesses different characteristics other BA.2 sub-lineages“. In other words, the centaur variant would not be more or less dangerous than the other sub-lineages of BA.2.

What is the origin of the Centaur variant?

In its risk analysis on the emerging variants of SARS-CoV-2 of July 6, 2022, Public Health France indicates that the majority of the sequences corresponding to the sub-variant BA.2.75 come fromIndia. It was first reported in India in May and then spread to other countries: United States, United KingdomGermany, Canada, Japan, Netherlands, Australia, Nepal, Indonesia, New Zealand, Denmark, Italy, China, Luxembourg… And in France since July 2022.

Percentage of BA.2.75 sequences among the interpretable sequences, by country and by sampling date (source: cov-spectrum.org on 05/05/2022, according to GISAID data). © Risk analysis of Public Health France variants

How many cases of the Centaur variant are there in France?

As of September 22, 2022: 60 cases of BA.2.75 were detected in mainland France, one case in Martinique and 2 cases in Reunion, reports the global tracking of scientist Raj Rajnarayanan.

  • 13 in Hauts-de-France
  • 11 in Occitania
  • 8 in the Great East
  • 4 in the Centre-Val-de-Loire
  • 3 in Ile-de-France
  • 3 in the PACA region
  • 2 in New Aquitaine
  • 2 in Brittany
  • 1 in Brittany
  • 1 in Pays de la Loire
  • 1 in Normandy
  • 11 in Auvergne-Rhône-Alpes

As of September 22, 2022, it represents 0.3% of interpretable sequences in France, in other words 3 Covid-positive people out of 1000 are infected with this variant.

What symptoms does the Centaur variant cause?

This sub-variant would have the same characteristics as the BA.2 and more generally the Omicron variant. It would therefore cause the same symptoms, namely:

  • A significant tiredness
  • cough
  • Fever
  • Headaches
  • Muscle pain or aches
  • Sore throat
  • Runny nose
  • Digestive symptoms: nausea, vomiting, diarrhea…
  • Sometimes a loss of taste and smell

Is the Covid vaccine effective against the Centaur variant?

A priori yes, since the centaur variant has the same characteristics as the BA.2.

  • HASafter two doses of vaccine, efficacy against symptomatic disease is 18% for BA.2
  • After three doses efficacy against symptomatic disease is 74% for BA.2.
  • Efficiency drops to almost 50% two and a half months after the 3rd dose for BA.2indicates a study by the British health agency published on February 25.

Regarding the treatments: among the monoclonal antibodies available, BA.2.75 has an overall similar sensitivity to BA.2 and BA.5, with disparities depending on the therapeutic monoclonal antibodies, reports Public Health France on September 7, 2022.

Sources: European Center for Disease Prevention and Control (ECDC) / Risk Analysis of Public Health France Variants / SARS-CoV-2 variants of concern and variants under investigation in England, UK Health Security Agency, 22 July 2022.

The article is in French

Tags: Covid centaur variant BA .2.75 symptoms France dangerousness

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