Third wave of Covid-19: "A speed race between variants and vaccines"

To date, less than two in ten French people have been infected with Covid.

According to the projections that the Institut Pasteur has just made public, vaccination should not slow down infections at this stage but could quickly have an effect on hospitalizations, as explained by Simon Cauchemez, member of the scientific council.

What should we expect in the coming days?

SIMON CAUCHEMEZ.

We must expect a difficult situation.

While lately, the indicators were rather down, we have seen for a few days that they are rising again.

As a result, our models anticipate an increase in hospital admissions over the next ten days in several regions.

How is this explained?

The slowdown in February is undoubtedly explained by the combined effect of the curfew, the holidays, perhaps the cold snap and a population that remains very attentive to the epidemic situation, but this effect is fading. .

In addition, the variants are becoming more and more predominant and make the control of the epidemic increasingly difficult: with equal control measures, they spread more in the population and can therefore cause more infections and hospitalizations.

The vaccination campaign has just entered its third phase.

LP / Arnaud Dumontier  

Nothing can slow down this runaway?

We are witnessing a race for speed between variants and vaccines.

At the start of a vaccination campaign of this type, the proportion of French people vaccinated is low and therefore, the effect on the number of infections is not very important.

On the other hand, since the most vulnerable are vaccinated as a priority, it is expected that the vaccination will quickly have an impact on hospitalizations.

According to our models, the number of hospitalizations could be almost twice as low on May 1 as it would be in a scenario without a vaccine.

This is the good news.

Unfortunately, the effect of the vaccines may be insufficient to avoid a strong resumption of the epidemic due to the variants.

The models clearly show that it is important to rapidly vaccinate as many vulnerable people as possible to overcome this difficult course.

You anticipate record levels of hospitalization before the summer ...

It should be understood that we are presenting scenarios, not predictions.

In a scenario where there is a slight increase in the transmission rate at the end of the February vacation and taking into account the effect of variants, hospitalizations are in fact expected to rise again significantly.

In this case, measures will undoubtedly be taken to break this growth dynamic.

We therefore simulate scenarios where additional measures prevent a third wave of even greater magnitude.

For this, we anticipate that it will be necessary to succeed in maintaining transmission rates at particularly low levels to counter the greater transmissibility of the variants.

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Yes.

There are also significant regional disparities.

In Ile-de-France, for example, an estimated 30% of the population has been infected, it is the region that has been the most infected in mainland France.

We also note differences by age group.

The 20-49 year olds are those who have been the most contaminated, up to 40% of them in Ile-de-France.

We are only talking about the adult population, over 20 years old.

With the infection, one is likely to have acquired immunity, at least partial and of short term.

But you have to be careful: while the infection probably confers short-term immunity, it is possible that the latter will fade over time.