5th wave: can vaccination prevent containment?

The question of re-containment during the fifth wave of this fall / winter in France is closely linked to that of vaccination.

The fifth wave of the health crisis is now certain in France. In the capital, we count 250 cases per 100,000 inhabitants at the end of November 2021, which reaches the maximum alert threshold. This incidence rate – that is to say the number of contaminations in a given population and period – is equivalent to that of the peak of the last wave. However, this fifth wave only seems to be starting.

Can the situation raise fears of confinement? What criteria should be taken into account to address this questioning?

Serious forms reduced by vaccines

The fifth wave is distinguished by the vaccination rate of the French population: more than 75% of eligible people are vaccinated at two doses. However, this comprehensive scheme reduces the risk that a covid infection will turn into a serious illness (or long-term covid) requiring hospitalization or causing death. This is proven by studies based on “real life” data, ie on the basis of vaccinations carried out in recent months. For example, a recent report of October 2021 estimates an effectiveness of 90% against serious forms (hospitalizations, death) in people over 50 years of age.

In fact, the fifth wave does not currently have the same structure as the previous ones. If the increase in the number of positive cases is dazzling, the number of deaths and hospitalizations is less consequent, not obeying the same evolution. Clearly, it could be a wave of contamination more than a wave of hospitalizations and deaths.

Situation au 24 nov 2021. // Source : CovidTracker

Containment is useful against hospital pressure

Containment is an overall effective measure to curb the spread of the coronavirus. Studies have shown this effectiveness, but with some limitations. These limitations mean in particular that such a decision is quite fraught with consequences. However, after two years which have greatly strained society, it is clear that a new confinement could have consequences. psychological and economic pretty hard. The measure, if it is taken again, should therefore be really well justified.

But then what, precisely, justifies confinement? It’s not really the increase in the number of positive cases. In reality, confinement comes to prevent or stop very specifically hospital pressure. When the contaminations curve reaches a certain stage, epidemiological models then often show that in the days and weeks that follow, this will have repercussions on hospital admissions as well as on deaths. This makes the care of patients more difficult, not to mention that the caregivers are overwhelmed.

Denfert-Rochereau metro station, deserted, at the time of the first confinement in 2020. // Source: L. Genet

Containment limits the number of contaminations to, precisely, stop or avoid this hospital pressure. This is what the Institut Pasteur reminds us to explain the rationale for its projections : « To be able to continue to welcome these patients, hospitals may have to deprogram certain operations, close non-COVID-19 services and reallocate staff in favor of COVID-19 care, with an impact that can be deleterious for COVID-patients. 19 and non-COVID-19 as well as for caregivers. These epidemic rebounds therefore generally lead to a strengthening of control measures, which should make it possible to reduce the pressure on the hospital system.. »

However, since vaccination limits the number of severe versions of the disease, it statistically reduces the number of intensive care hospital admissions. This alleviates the risks of hospital pressure. In fact, the risks that containment will be necessary in France are much lower than during all the previous waves.

However, there is uncertainty as to the duration of immune protection: the effectiveness of vaccines seems to decrease over time, especially after 6 months, hence the current strategy of a booster dose for those most at risk of contacting serious forms. The booster vaccination rate could therefore have an impact on hospital pressure. In addition, the Institut Pasteur noted that “ a flu epidemic concomitant with the COVID-19 epidemic could, however, increase the pressure on the health system “. The risk of the flu coming back in force all the more justifies the maintenance of barrier gestures.

In Germany, the government has also announced a tightening of restrictions for unvaccinated people specifically in regions where the number of hospitalizations exceeds the alert threshold. In Austria, confinement was decreed after a record in the number of contaminations (1,531 cases of Covid-19 per million inhabitants on November 21, 2021, the previous record was around 800), which raised fears of a hospital rebound as a result. The decision to lockdown is therefore also very contextual at the national level.

Announcements by Olivier Véran Thursday, November 25

The probability of a re-containment is therefore relatively low in France. However, there are still some uncertain factors that could possibly push the authorities to consider this solution. On Thursday, November 25, the Minister of Health Olivier Véran planned to announce new measures to stem the 5th wave, but the method of containment is far from being on the program, if we are to believe recent findings spokesperson Gabriel Attal at the end of the last defense council.

As is often the case, since the beginnings of the epidemic, we would like to point out that the “uncertainty” factor is in itself a matter of real information to be taken into consideration. The models, projections and already established knowledge are not enough to foresee everything or to know everything, a fortiori in a context where the situation is changing a lot – sometimes quite quickly.

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