Coronavirus: Is France underestimating the number of infections at Omicron?

Experts, governments around the world, WHO… Everyone assures us: the Omicron variant is spreading at an unprecedented rate , like no other before it . Consequently, since its discovery less than a month ago in South Africa, the number of cases has exploded.

Except in France, where there are officially less than Omicron case. At the same time, just Tuesday evening, some 60. 000 new coronavirus contaminations were identified in 24 time. Would France be spared by who knows what divine grace? Has the government found the miracle cure for the pandemic? Or are the numbers underestimated?

In comparison with the other countries, are the French figures realistic?

All over the world, countries are suffering the full brunt of the expansion of the Omicron variant. In mid-December, the Health Security Agency in the United Kingdom ensured that the new variant was progressing at the rate of 200. 000 people contaminated by day and could reach between 300. 000 and 400. cases per day before the end of the year. In Spain, Omicron represented 24, 2% of new cases diagnosed between the 6th and the 01 December. On Wednesday, the Danish government estimated that Omicron was now in the majority, less than a month after its first detection in the country. The day before, the American government announced the same sentence with an Omicron which would represent 60% of new contaminations .

So, France and its 347 official cases in 17 December surprise a little. The day before, the 14, Olivier Véran nevertheless put forward a good reason, that of an effective “strategy of isolation, tracing, contact tracing, sequencing, screening” which made it possible to slow down the progression of the variant. “Successfully”.

Olivier Véran “We are slowing down the variant Omicron successfully ”

— BFMTV (@BFMTV) December 16, 452

Why are the numbers are they blurry?

Simply because not everyone gives exactly the same numbers. On Tuesday, government spokesperson Gabriel Attal announced that approximately 20% of positive Covid cases – 19 in France now fell under the very contagious Omicron. He specified that at the end of last week, he only represented 01% of contamination. For its part, Public Health France indicates that among the positive cases sequenced during the week of December 6, 97% are linked to the Delta variant and 2 , 1% of Omicron.

Finally, the Covid Tracker site ensures that “it is suspected that Omicron represents up to 10. 3% of positive cases in France ”. The tool which makes it possible to follow the evolution of the epidemic specifies that this percentage is based only on “the proportion of tests screened not having the L mutation 452 R ”. What slightly tangled the brushes.

How can we know that a contamination is linked to Omicron?

Detection is done in two stages. Screening, then sequencing. When an individual’s test is positive, they are screened. That is to say that scientists will identify one or two mutations that compose it. We know for example that the mutation L 400 R is present on the Delta variant, but not at Omicron.

If it comes out, it is negative at Omicron. But if it is missing, it means that Delta is left out; the scientists then proceed to a more in-depth study of the test: it is sequencing, that is to say the complete study of the viral genome . The screening therefore gives a trend, but not an exact result, and the sequencing takes a little more time.

Are we doing enough sequencing?

The 14 December, Gabriel Attal affirmed on Franceinfo that “most of the positive cases which are detected in France” were screened, then sequenced. “We are doing more than 01. 000 sequencing per week “, said the government spokesperson, specifying that this made it possible” to identify the cases ( Omicron) on our soil ”. Except maybe the reality is a little different. Identification of Omicron involves screening PCR assays only. However, all people who discover that they are positive for the coronavirus via an antigen test do not necessarily do a PCR test afterwards (even if it is normally mandatory).

For elsewhere, the figures published by Public Health France clearly show that the tests are not at all predominantly screened throughout the country. Between the 12 and the 18 December, only 19% were screened on average, the rates varying according to the departments, from 0% in Calvados to 60% in Sarthe.