Covid-19: the new increase in contaminations in France caused by BA.2, a sub-variant of Omicron? – LCI

The peak is long overdue. While the number of patients admitted to critical care has stabilized in the country, the number of contaminations continues to increase. On Wednesday January 19, more than 436,000 people tested positive in France, 20% more than the previous Tuesday. In two regions – Île-de-France and Corsica – the number of new cases had however decreased, before starting to rise again for a few days.

However, some of our neighbors are seeing a significant drop in contamination. This is particularly the case of the United Kingdom. Others, like Spain, seem to be reaching the peak of this fifth wave. But not France. Among the hypotheses to explain this phenomenon, the possible presence of a sub-variant of Omicron, baptized BA.2, on our territory. Professor Antoine Flahault, director of the Institute of Global Health in Geneva (Switzerland), responds to LCI.

The peak of the fifth wave has still not been reached in France. How to explain it?

The current level of contamination thwarts the predictions of the arrival of the peak. This reminds me of the situation in mid-December. Our models then predicted a possible peak of the Delta wave, but the Omicron variant came to connect and there was no descent in France. I don’t know if the current rise, somewhat unexpected, is attributable to the Omicron variant, or if it should be attributed to the arrival of a sub-variant, as is the case in Denmark.

What do we know about this sub-variant, baptized BA.2?

This subvariant has 28 more mutations than Omicron, but we don’t know much yet. It has been spotted in several countries, such as Israel, Singapore, India and China. We do not know its origin, its virulence, or its ability to escape immunity, including that conferred by Omicron. On the other hand, it seems to be more contagious. It has already become the majority in Denmark, a country that sequences strains a lot. In France, the sequencing is less. It is therefore difficult to know the real share of BA.2, but we will find out soon.

Should we worry about the emergence of mutations?

We expected new variants. We are bound to have false alarms, like Deltacron. But I don’t think that’s the case with BA.2, spotted by several teams around the world. It will quickly be necessary to know if it escapes the immunity conferred by the vaccine and previous infections and to know more about its virulence. Let’s take a close look at the Danish situation, which will be the most enlightening on the subject.

If this sub-variant is confirmed, should we expect a further increase in contamination in the coming weeks?

This pandemic greatly thwarts predictions. Even at seven days, I can’t tell if it will go down or keep going up. If several waves combine on top of each other, it is even more difficult. The key is whether this subvariant can reach people who have just been infected. It’s unlikely, but it needs to be studied closely. Until we have the answer to this question, forecasting is a very perilous exercise.