Q: “The Omicron variant, more contagious, but less virulent than the Delta, isn’t it the light at the end of the tunnel? Collective immunity is rapidly being increased with a low hospitalization rate… ”
Maurice Jean
A: You are right to say that a much less virulent virus which would supplant the others thanks to its high contagiousness would be a blessing. There has been some hope that this is the case for Omicron. Unfortunately, it seems that this new variant is much more of a problem than a solution.
Everything is in the degree of contagiousness and virulence of the variant, as well as in its ability to bypass vaccination.
Take the simple example of a less virulent variant that would halve your chance of going to the hospital, but which would be four times more contagious than the previous strain. In the end, it would cause twice as many hospitalizations as the other.
The numbers for Omicron are not yet fully established, but they point to a situation like this.
If there is one certainty today, it is that Omicron is much, much more contagious than the Delta variant. Latest report from UK authorities speaks of 3.2 times higher transmissibility1.
Virulence? It is less well known. South African study finds Omicron generates 29% fewer hospitalizations than previous strains2. But it could be that Omicron looks sweeter than he actually is. It is because it manages to infect people who have been vaccinated and people who have already had the disease, and these people are generally less sick.
In short, the negative effect of Omicron’s very high transmissibility outweighs the positive effect of its lower virulence, if the latter turns out to be.
The other problem is that Omicron partially foils our vaccines. According to the South African study, for example, two doses of Pfizer’s vaccine protected 80% against a Delta variant infection, but only 33% against Omicron. Protection against hospitalizations is better (70%), but less good than for Delta (93%).
A third dose of Pfizer, regardless of the nature of the vaccines previously received, would increase protection against infections of the Omicron variant to around 70%, according to UK data. Hence the commotion to speed up its administration.
Quebec projections from the National Institute of Excellence in Health and Social Services (INESSS) published last Thursday clearly show that, far from reducing hospitalizations, the Omicron variant unfortunately risks making them soar.3.