Code name: B.1.617.
With this so-called "Indian" variant of SARS-CoV-2, "there is a new deal" which is taking hold, recognized the government spokesperson, Gabriel Attal, on Wednesday.
More transmissible, causing more serious forms, escaping vaccines ... Much has been said about the one who was described at the beginning of "double" or even "triple mutant", because of the amino acid mutations on the protein "Spike" of the virus.
It is this which allows it to enter our cells.
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We take stock in this article on what we know, what seems likely, and what remains to be speculated.
To begin with, it should be noted that this “Indian” variant, classified as “worrying”, groups together three different sublineages: B.1.617.1, B.1.617.2 and B.1617.3.
This is the second that interests us in priority, since it is the majority in France (36 out of 46 outbreaks of at least one case of the Indian variant identified on May 25, according to Public Health France).
It is even now dominant among all the new contaminations identified in England, which have increased by nearly 20% in one week.
More contagious, but by how much?
"It is probable that B.1.617.2 is more transmissible than B.1.1.7 [the so-called British variant, which became the majority in the United Kingdom at the end of December then in France at the end of February, Editor's note]", notes the agency Public Health England in its latest risk analysis, published Thursday, May 27. "It has a transmissibility which seems higher than the historical strains, but also that the variant [" British "], one can in particular see it on data in vitro", supplements Sibylle Bernard-Stoecklin, epidemiologist at Public health France
.
B.1.1.7 is already more contagious than the starting strain, which caused the first two waves of the epidemic. Scientists generally suggest a range of between 40 and 70%.
The spread of this Indian variant is "faster" in affected areas, notably the English towns of Bolton, Bedford and Blackburn, and this "cannot be fully explained by types of contact or behavior".
In other words, a slackening of the population cannot explain on its own why B.1.617.2 is spreading there so quickly.
The explanation could come from the L452R mutation, "which would be associated with a risk of increased transmissibility of the virus", indicate Public Health France and the National Reference Center for Infectious Disease Viruses in their latest risk analysis.
VIDEO.
B.1.617, the "double mutant" variant which explodes the epidemic in India
How much faster does it spread?
Difficult to answer precisely at the moment.
The Scientific Advisory Group for Emergencies (Sage) considers “possible that it is up to 50% more transmissible”.
“50% is maybe a little overestimated.
Still, we can clearly see an increased transmissibility in the cities where this variant circulates the most, ”emphasizes epidemiologist Antoine Flahault.
Sibylle Bernard-Stoecklin calls for her side to "remain cautious" with these figures, pending "additional data in real life".
"It is spreading faster at the moment than B.1.1.7, but we cannot yet know to what extent it is because it is more contagious or because it escapes immunity", adds the biologist Samuel Alizon, research director at CNRS.
No evidence for more severe forms of the disease
"There is not yet clear evidence of a difference in the severity of the disease following infection with this variant," notes the British equivalent of our scientific council.
"Most of the cases are recent and the follow-up time is insufficient to allow an assessment of the severity", adds Public Health England.
However, hospital admissions have increased by 20% in one week, without it being possible to say whether this is a simple consequence of the increase in infections or if the variant is also more "nasty".
All regions are affected, especially the North West, reports Financial Times journalist John Burn-Murdoch, who does not hesitate to speak of a new "wave".
NEW: B.1617.2 is fueling a third wave in the UK, with not only cases but also hospital admissions rising.
Vaccines will make this wave different to those that have come before, but it remains a concern, and one that other countries will soon face.
Thread on everything we know: pic.twitter.com/4825qOqgrl
- John Burn-Murdoch (@jburnmurdoch) May 27, 2021
The "positive" point being that the oldest seem this time relatively spared thanks to vaccination, which should limit the number of deaths.
The most problematic mutation missing
What distinguishes B.1.617.2 from the other two sublineages is in particular that it does not have the E484Q mutation.
This is certainly good news.
Indeed, this "could have an impact in terms of immune escape (post-infection and post-vaccination)", indicated the Directorate General of Health from April 26.
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As often, this “has not yet been formally demonstrated”.
Moreover, the 201 / E484Q variant, also possessing the E484Q mutation and detected in several outbreaks in Bordeaux, seems to have spared the oldest populations and therefore vaccinated, recently reported the Regional Health Agency of Nouvelle-Aquitaine.
Cluster in Bordeaux: "it's on the basis of the British variant, it's a mutation," says the director of ARS Nouvelle-Aquitaine pic.twitter.com/qQwY4DQ1TM
- BFMTV (@BFMTV) May 22, 2021
A few cases of reinfection by B.1.617.2 have been identified across the Channel, "but this phenomenon is foreseeable for any prevalent variant", temper the French authorities.
Initial data from England suggest that the efficacy of the vaccines would remain almost as good as against B.1.1.7, but on the condition of administering two doses.
Among the more than 4,500 people infected with this variant and whose vaccination status is known, nearly three quarters had not yet received any dose.
“Before the deployment of vaccination, I thought it would be illusory to think that we could differentially control the spread of such and such a variant. I reviewed my judgment, I recognize that effectively controlling the chains of transmission linked to a new worrying variant saves time for vaccination, ”says Florence Débarre, CNRS researcher in evolutionary biology. The “race the clock” between variants and vaccination is therefore more topical than ever.