Is Covid-19 on the way to becoming a childhood disease with schools as possible places of transmission? In the United States, in Israel (where 4,500 students and 734 teachers were placed in quarantine at the beginning of June), in Great Britain, but also in Switzerland, many cases of SARS-CoV-2 are now declared in children, in especially in those between 10 and 19 years old.
“An increased transmissibility in all age groups has been reported for the variants of concern of SARS-CoV-2, in particular for the Delta variant, point in this regard the last report of the European Center for Disease Prevention and Control (ECDC) on Covid-19 in children and the role of schools in the transmission of the virus. In regions where an increasing percentage of adults are fully vaccinated against Covid-19 but where children are not, we can expect that over the next few months we will see increasing proportions significant cases of SARS-CoV-2 in children. ”
A study conducted by the University Hospitals of Geneva (HUG) and the University of Geneva (Unige), the results of which were made public on Tuesday, July 13, also confirms that children have formed the age group most affected. by the circulation of the virus during the last six months. This is evidenced by the sharp increase in seroprevalence (i.e. the presence, in the blood, of antibodies specific to SARS-CoV-2) in the youngest age groups, with a doubling of immunity in those less age 6, which reaches 25%, and an increase of 15 to 30% in the number of people who have been infected among those aged 6 to 18. According to the results of this research, 12 to 18 year olds are currently 40% to present antibodies as a result of natural immunity, compared to 35% among 6 to 12 year olds.
Share of school environment
“This increase in the number of children to have been infected with SARS-CoV-2 is also to be linked to the decision to keep nurseries and schools open during the second wave, analyzes Silvia Stringhini, head of the unit of population epidemiology of the HUG and co-leader of the study. With the increase in vaccination in the adult population, we will certainly see a greater circulation of the virus in schools. Fortunately, children rarely develop severe forms of the disease, but many young people, especially between the ages of 12 and 15, who are the most affected age group, have reported to us symptoms that persist over several weeks. we call a long covid. These resolve themselves most of the time, but they sometimes generate several weeks of absence from school. ”
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Faced with this situation, and the possible occurrence of a new wave of infections in the fall in connection with the exponential spread of the Delta variant, should we consider specific measures to be put in place for the start of the school year? Although the role of schools in the transmission of the virus within the community is still debated, for the European Center for Disease Prevention and Control, things are clear: “given the probable risk of continued transmission among children not vaccinated, it is imperative that there is a high level of preparation in the education system for the 2021/2022 school year ”.
Set of measures
According to Antoine Flahault, director of the Institute for Global Health at the University of Geneva, the challenge today is to achieve the most standardized education possible in good sanitary conditions, in order to avoid school closures. . “For this, three types of measures can be implemented,” explains the latter. Vaccination should be further promoted for over 12s and teachers, or even made compulsory, which would avoid multiple interruptions that end up weighing on an entire generation. ”
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“In addition, it is important to achieve efficient ventilation of nurseries and primary schools, which would limit the risk of transmission in unvaccinated children, by installing CO2 sensors in classrooms and common rooms, such as canteens, even air purifiers when the controlled mechanical ventilation is not powerful enough, adds Antoine Flahault. Finally, depending on health trends, the question of wearing a mask for children over 6 years old should arise. All of these measures are obviously cumulative and must be proportional to the risk. If the transmission of the virus is low in the community, it is quite possible to relax certain behaviors. “
In a correspondence published at the end of March in The Lancet, an international team of epidemiologists also recommended, as another measure to “make schools safer”, to “test twice a week all staff and secondary students.” “Testing is the area that has been the most poorly evaluated from a scientific standpoint,” explains Antoine Flahault. We therefore still do not know what the best strategy in this area is. ”
Refusal of mass screening
What about the cantons? Are they already considering measures for the start of the school year? Among those we contacted (Vaud, Valais, Geneva, Neuchâtel), the strategies differ significantly. However, with one thing in common: the refusal of systematic mass screening in schools as recommended by the Federal Council. “This measure was introduced in a few German-speaking cantons for 100,000 students tested once or twice a week,” describes Cesla Amarelle, head of the Department of Training, Youth and Culture of the Canton of Vaud. Only a handful of positive students have been identified in this way. At this stage of the pandemic, we believe that targeted screening, where an entire class is tested when positive cases are detected, are more relevant. ”
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On the Geneva side, most of the prevention will focus, at the start of the school year, on the school environment, which will represent the part of the population with the least immunity, by implementing a so-called reactive testing strategy. “The goal is to break the chains of transmission early in order to keep the classes open as widely as possible,” specifies Lena Després, assistant doctor to the cantonal doctor of the canton of Geneva. If several cases are detected within a class, the strategy is activated and a mobile team moves to detect all the students in the class whose parents have given their consent. This screening is repeated five to seven days later, until there are no more positive students. At this time, we can estimate that the virus is no longer circulating. Our experience in June showed that both students and parents support this measure. ”
The mask, subject of uncertainties
Considered as gadgets for Christophe Darbellay, head of the Department of the economy and training of the canton of Valais, who advocates “common sense” regarding the ventilation of classrooms, CO2 sensors are the subject of a policy more structured in the canton of Vaud, the only one interested in it for the time being. “In the field, these sensors have an obvious educational added value and are accompanied by an awareness campaign on the way and the importance of managing ventilation. We would like all classes that are interested in it to have it available in the fall, confirms Cesla Amarelle. Orders are regularly placed in this direction and we are also working with the Technical and Trades School in Lausanne to manufacture them. ”
Will wearing a mask be reintroduced at the start of the school year? Cautious, the canton of Neuchâtel is in favor of keeping it indoors for adults and students from 9th to 11th grade, while specifying that these elements will be adjusted in the week preceding the start of the school year. “The spread of the Delta variant is not very reassuring, but we are still considering a back-to-school period without masks, argues Christophe Darbellay for his part. However, this can change depending on the health situation. A meeting with the cantonal directors of public education is already planned in order to coordinate one last time before the start of the school year. ”
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