“It is not necessary to wait”

It is one of the control points for the epidemic. Vittoria Colisa, director of research at Inserm (Pierre-Louis Institute of Epidemiology, Inserm/Sorbonne University), which is preparing new models, stresses that more regular testing at school could help reduce the number of infections. She supports the immediate injection of a third dose of the vaccine to everyone. “We should not wait any longer, there is no longer any reason to prioritize such and such an age group!” she explains.
Does the rapid spread of the epidemic in France surprise you?
No, the fifth wave is not unexpected. Winter conditions, temperature and humidity aid circulation and transmission of the virus. Our behavior is turning inward, as the risk of pollution by aerosols increases. The wave is there, even if it is delayed a little and slowly in France, Italy and Spain compared to other European countries.

How do you explain that?
This is related to the relatively high vaccination coverage, but also to the favorable climatic conditions in the south compared to the countries of the north, where the outbreak was very rapid. Another very important factor: the fact that you keep passing through all summer. Some countries, such as Denmark, have staked everything on vaccination and abandoned other health measures. The situation is strange in Great Britain, with the infection rate high but steady, as for other indicators (hospitalization and deaths), while the barrier measures are being lifted. But part of the population continues to work remotely.

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Those under the age of 12, who do not get vaccinated, currently make up a large population group for circulating the virus.

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Is the number of cases still a relevant compass?
Yes, we must continue to monitor the incidence, along with other indicators, to understand whether the difference between the curve of the number of cases and that of hospitalization is changing. On the other hand, grafting will widen the gap; On the other hand, the increasing infection of the virus will push in the opposite direction. Although the vaccine helps curb the epidemic, the delta variant is twice as transmitted as the strain from last winter and has twice the chance of getting severely ill from the disease.

What do your latest predictions say?
We are in the process of updating our models. It’s complicated because the variables are numerous: vaccination coverage, its rhythm, the third dose to be administered, first estimates of the decline over time in vaccine efficacy against infection…Our team focuses on the school by re-adjusting our models with delta-variable properties and integrating field data to understand school prevalence.

With more than 4,000 classes closed, is school a driving force behind the spread of the virus?
In general, the figures for the circulation of the virus in institutions are not estimated. Closing rows is only what we see, we see very little! Most of the time, children are asymptomatic or have symptoms that are difficult to recognize. Those under the age of 12, who do not get vaccinated, currently make up a large population group for circulating the virus. Thanks to our models and by analyzing screening data in institutions during the third wave, we have highlighted a high level of transmission in schools, which contributes to the spread of the virus in the community. It also proved that during the third wave, closures such as school holidays slowed the epidemic. According to the models, when you test regularly in school, you reduce the number of school days lost on average per student as well as reduce the number of cases. It is a very strong preventative measure.

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A large wave of cases is expected, as seen in some neighboring countries

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Are hospitals at risk of saturation?
This is the big question. The dynamics and level of hospitalization are indicators that must be monitored in order for any new restrictions to be established. Especially with the fatigue of nearly two years of the pandemic and a possible winter wave of influenza. But we cannot give an intuitive answer, we have to wait for the next mathematical prediction. A large wave of cases is expected, as has been seen in some neighboring countries. This will follow the number of hospitalizations, with a larger difference between the two curves depending on the level of vaccination.

Austria is reshaping, and Germany is taking drastic measures. Will France escape from the new restrictions?
I can’t say what the health effect will be at prime time. But we have many tools to avoid getting there and respond to this wave. Starting with the third “booster” dose. From the point of view of the epidemic, it is urgent to exploit, since this recall helps to “push” protection against infection. The vaccine was developed against the Wuhan strain, and is still very effective against severe forms after infection with the delta variant, and has not been won. It also reduces the risk of infection and the development of symptomatic forms. But the most recent results show us that this efficacy against infection is lower due to the variant and decreases over time after the second dose. Hence the benefit of a third injection.

Do you stand up for this “boost” for everyone right away?
Yes, we should not wait any longer, there is no longer any reason to prioritize this age group! We no longer have a problem with presentation or management as at the beginning of the campaign. The “booster” works in prevention: it increases the effectiveness of the vaccine against infection so that a person exposed to the virus has a much lower chance of getting infected. We need to reduce viral circulation in the population to reduce hospitalizations as well. The reminder is the barrier measure that, in concert with expanded vaccination coverage, will curb the epidemic.

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If the vaccination is safe and effective for children, it will help slow viral circulation in the general population.

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With 87% of those over the age of 12 vaccinated, have we reached a glass ceiling?
The problem is that we don’t know if they are “strong” opponents, if they stall, if they can’t get to the vaccine… We have to go and get that part of the population. Who remains unvaccinated with the risk of hospitalization and who spreads the virus. Even if you get to a fraction of it, it can still have an effect. Because if the effectiveness of the vaccine is very high against severe forms, it is not 100%. With so many injured people, mathematically, we would regret further hospitalization.

What are the other weapons?
Barrier signals – even if we can understand the boredom of the French! We still have a few tough months ahead. We know these unpleasant rules, and they must be tightened: they are very important braking measures that will avoid other, more restrictive rules. Keep the mask, even with the sanitary aisle, in the theater, cinema, and restaurant until the meal. Airing the building is more difficult in winter but is very effective and is often forgotten. And of course, working remotely, a simple lever has an effect even when there are no other restrictions.

Should children be immunized like Israel or the United States?
The European Agency is evaluating the safety of the vaccine for them, with clinical studies currently based on a few thousand children. Real-life data will soon arrive from the United States. If this vaccination proves to be safe and effective for children, it will help slow viral circulation in the general population.