"Californian" variant of the coronavirus: many fears but still few certainties

His speeches regularly make the event.

That granted Sunday to BFMTV was no exception to the rule.

The President of the Scientific Council Jean-François Delfraissy warned of the “pandemic within the pandemic” represented by the discovery in recent weeks of numerous mutant versions of SARS-CoV-2.

"The new English, South African, Brazilian and now Californian variants have completely changed the situation for three weeks now," said the French doctor specializing in immunology.

These clones show “a significantly higher transmission factor and accelerate the transmission of the virus”.

If these observations are no longer in doubt concerning the greater contagiousness of the first two, we must still remain cautious about the others.

And in particular on the so-called Californian variant.

Explanations.

Simple "coincidence" with the epidemic wave?

The first official message goes back seven days.

On January 18, researchers at Cedars-Sinai Medical Center in Los Angeles report the detection of a new variant.

It was while hunting down the English strain in the laboratories that they came across a new combination of “five recurrent mutations”, one of which was in common with the English one.

Its name: "CAL.20C".

They had spotted it for the first time in July in the sequencing centers, then nothing until November.

Now it is in the majority in certain areas.

But is it more contagious, more dangerous, more resistant to vaccines?

Or even able to bypass the immune response?

Today, none of these questions can be answered with certainty.

However, the unprecedented epidemic wave hitting the West Coast state since December is necessarily raising a lot of fears.

"The predominance of this strain coincides with the increased positivity rate observed in this region," say the Californian researchers in their study - which has not yet been validated by peers.

They are particularly concerned about certain mutations located at the level of the surface protein "spike".

It is through this that coronaviruses enter human cells, but also through which the antibodies generated by vaccination target.

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It remains to be confirmed that this new variant is directly responsible for this explosion of contaminations.

The research team "is not sure what the new findings mean in terms of infectivity and resistance to antibodies," warns Wenjuan Zhang, assistant professor in the department of molecular pathology and laboratory medicine, and lead author of the study.

The completeness of the samples needs to be improved.

The American geneticist and biologist Trevor Bedford has also advanced on Twitter the hypothesis that this variant would certainly have contributed to the epidemic outbreak but that it would not be at the origin.

A wave on the downward slope

In addition, the surge in contaminations, serious cases and deaths observed in recent weeks seems to have peaked last week.

Since then, the number of positive tests has declined markedly (see graph above), in particular in the southern part where the variant was detected first and sometimes represented between 30% and 50% of the genomes analyzed in mid-January.

But once again difficult to draw conclusions.

In either direction, the various explanatory factors (respect for barrier gestures, temperatures, end-of-year celebrations, etc.) are often intertwined.

According to NBC, these signs of improvement will still push Governor Gavin Newsom to ease the containment measures put in place since early December on Monday.

"We are seeing promising signs that California is slowly emerging from the most intense phase of this pandemic," said Brian Ferguson, deputy director of crisis communications and public affairs in the governor's office.

Note that the variant has since been discovered in New York and Washington DC and even in Oceania.

Sequencing work now essential

This suspicion around the Californian variant shows just how crucial the sequencing and sharing of the data obtained is to closely follow the evolution of the pandemic.

However, like vaccination campaigns around the world, there are great inequalities in resources from one country to another.

Great Britain and Denmark excel in this area, but not France for example.

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Maria Van Kerkhove, WHO COVID-19 technical manager, recently called the number of sequences shared so far "unbelievable".

While deploring that they only come from a handful of countries.

“Improving the geographic coverage of sequencing is essential for the world to have eyes and ears (on) the changes in the virus,” she said in an online forum.

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This mission is all the more essential since between the appearance of a variant and its explosion in the population, more than three months can elapse. In the United States as in France, research institutes estimate that the British variant will not become the majority until March. This delay is a "chance", you have to know how to seize it very quickly.