It is in the sights of scientists: the variant BA.4.6. It is a sub-variant of the BA.4 variant, ie a second generation variant of Omicron.
What do we know? It has an additional mutation compared to BA.4 and BA.5: the R346T mutation. And especially, it is slowly gaining ground in the United States : BA.4.6 is now responsible for around 7% to 10% of new Covid-19 infections, according to the data from the United States Centers for Disease Control and Prevention. Nevertheless, it doesn’t seem to win (for the moment) against BA.5, the dominant variant in the United States.
In France, the BA.4.6 sublineage was first detected in mid-June and its detection during Flash surveys seems to be stabilizing around 2%. Like the BA.2.75 variant (or Centaure variant), the Omicron BA.4.6 sub-variant is nevertheless monitored by the French health authorities. “This emergence of new sub-lineages is a normal and expected evolutionary phenomenon”, comments Public Health France, in its analysis of the variants of September 7.
Immune escape?
Evusheld, a treatment combining two antibodies indicated to prevent Covid-19 infection cin immunocompromised people not responding correctly to vaccination, would not be effective against the BA.4.6 subvariant. This is shown by a study from Columbia University published on September 6. in a preprintnot yet peer-reviewed. “Just be aware that BA.4.6 is going to be resistant and gaining ground on BA.5. So immunocompromised people in general should be more cautious”commented at CNNDr. David Ho, professor of microbiology and immunology at Columbia University. Indeed, if this treatment were to disappear for lack of effectiveness, this would reduce the molecules available for immunocompromised people resistant to vaccines. “There are millions of people who have compromised immune systems, and they would be out of options right now”did he declare.
Sources:
- Risk analysis on emerging variants of SARS-CoV-2 carried out jointly by Public Health France and the CNR Respiratory Infections Virus, SPF, September 7, 2022.
- New Omicron offshoot BA.4.6 evades protection of Evusheld’s antibodies, study finds, CNN, September 7, 2022.
