Covid-19: what level of vaccination to get out of the health crisis?

How long will the restrictions be necessary? Regarding the wearing of the mask, Emmanuel Macron said, during a distance exchange with third-grade students on April 6, that it would be necessary “Wear the mask at least until summer”, and indicated that the reopening of a series of places (theaters, cinemas, terraces) would be “Slower than last May 11”.

→ ANALYSIS. Covid-19: is the course set by Emmanuel Macron realistic?

The same day, the Institut Pasteur put a study online seeking to anticipate the level of vaccination coverage necessary to be able to relax the control measures, depending on the progress of the campaign by age group. The team of modellers, led by Simon Cauchemez, presents several scenarios for the fall of 2021, taking into account the impacts of the English variant which has become dominant, and which do not outline a rapid end to the constraints.

Vaccinate as much as possible to loosen the vise

In a first hypothesis where the reproduction rate of the virus would be equivalent to that of the first wave of spring 2020, the vaccination of 90% of over 65s and 70% of adults would be enough to do without restrictions. But, with variants, the reproduction rate will probably be higher and “More than 90% of adults would have to be vaccinated for a complete relaxation of control measures to be possible”.

A still distant goal when barely more than 5% of adults have already received two doses in France and reluctance to vaccination, especially with regard to AstraZeneca, could slow the pace. According to a note from the European Commission relayed by AFP, France, Italy, Germany, Spain and the Netherlands could vaccinate, by the end of June, between 55% and 65 % of their total population (58% for France), or about 70% of their adult population. To reach the threshold set by the Institut Pasteur and get out of the virus’ grip, vaccine mobilization will therefore have to continue during the summer.

Also in this scenario of a high level of reproduction of the virus, the researchers estimate that it will be necessary to maintain control measures to reduce transmission in the general population, up to ” 15 to 27% “, Knowing that the strict confinement of March-May 2020 had reduced this transmission by 80%, and the second confinement by 70%. Without further details, Simon Cauchemez told the World “thata mixture of different measures’ would be necessary. A mix of barrier gestures, reinforcement of the “test, trace, isolate” system… and perhaps curfews and other movement restrictions.

Broaden audiences?

The authors also repeatedly raise the issue of vaccinating the youngest, who certainly have a lower risk of developing severe forms of Covid-19, but who “Play an important role in transmission” : integrating them into the campaign would “To reduce the circulation of the virus and therefore indirectly protect the most vulnerable”.

→ READ. Covid-19: should children be vaccinated?

The research team recognizes that the goal of immunizing 90% of adults is ” Student “, she emphasizes that “If only adults are vaccinated, a large epidemic is expected in children, contributing to the infection of unprotected parents and grandparents”. Therefore, and “If vaccines are shown to be safe in children”, the vaccination of two-thirds of people aged 0 to 64 and 90% of those over 65 could allow control measures to be completely relaxed.

A projection that echoes the announcements of the laboratories: the previous week, Pfizer indicated that its vaccine is 100% effective in adolescents aged 12 to 15, and is conducting tests on children under 11.


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