Only a few days left before the start of the school year! On September 2, millions of children will return to school after a summer marked by the exponential spread of the Delta variant. A variant which, unlike the strains that preceded it, affects children more, as shown by the contamination figures in the youngest, and which raises fears of a new epidemic rebound in this young unvaccinated population.
But for the health authorities, if it is necessary to further advance anti-Covid vaccination in adolescents, that of those under 12 is not on the agenda.
Rising incidence rates in children of all ages
Now, the Delta variant is identified in “98.7%” of the samples sequenced, indicates Public Health France in its latest epidemiological bulletin. A much more contagious variant: its transmissibility is “about 2 times higher” than “the historical viruses and than the Alpha (about 40 to 60% more transmissible), Beta (about 60%) and Gamma (about 30%) variants” , noted at the end of July Public Health France in a risk analysis on emerging variants. A high transmissibility associated with an increased viral load, approximately “1,260 times higher than the historical strain”, pointed out a study conducted by researchers from the Center for Disease Control and Prevention of Guangzhou in China, pre-published on the medRxiv site.
Consequence: an explosion in the number of patients, and, by extension, an increase in contaminations also observed in children, until then very little contaminated. “In young children, incidence rates are increasing in all age groups: 65 [cas] per 100,000 inhabitants among 0-2 year olds (or + 17%), 95 among 3-5 year olds (+ 15%) and 200 among 6-10 year olds (+ 14%) ”, notes Public Health France. A Delta variant that can make you sick from the first days of life. In recent days, pediatricians have observed an upsurge in Covid cases in infants, most often infected by unvaccinated parents.
Thus, in children from 0 to 9 years old, contaminations have multiplied by 10 in a few weeks, going from 856 cases recorded between June 21 and 27 to 8,516 new cases recorded between August 2 and 8, according to the data. collected by CovidTracker.
Little risk of serious forms, but a reservoir of circulation of the virus
An increase in contamination which is accompanied by an increase in hospitalizations. To date, 56 Covid children under 10 are hospitalized in France, including 7 in intensive care. Figures certainly increasing, but low, attesting to the low risks of severe forms of Covid-19 in children. But “mathematically, there will be more infected children, with the risk of being hospitalized or of having serious forms”, fears Professor Robert Cohen, pediatrician infectious disease specialist, and president of the National Professional Council of Pediatrics; While since the start of the epidemic, France has deplored less than ten deaths of children for 5,000 hospitalizations and 700 passages in intensive care.
Because if today, more than 70% of the population in France has received at least a first dose of vaccine, “there remains a vulnerable population”: the under 12 years old and the 42% of 12-17 years old who are not. not yet vaccinated, underlines epidemiologist Antoine Flahault. A young population which constitutes a potentially important reservoir of circulation of the virus from the next few days with the start of the school year, and which could lead to a new epidemic rebound. “There will be a mix, we will put in contact individuals who have not seen each other, coming from different places”, especially tourist areas where the virus has circulated a lot, warns epidemiologist Mircea Sofonea. And ‘once infected, [les enfants] will easily find among their relatives the 5% of the population (at risk) which is enough to make a wave, ”adds Antoine Flahault.
Thus, according to Arnaud Fontanet of the Institut Pasteur, the models of his research center predict that “half of new infections will occur in children from the fall”. A scenario resulting directly from the specificities of the Delta variant. Whereas previously, children transmitted Covid-19 less than adults, “with a variant two to three times more transmissible, children are now as contagious as adults were with previous strains”, underlines Professor Cohen .
But no vaccination planned for children under 12
So, should the youngest be vaccinated? To date, 58% of 12-17 year olds have received a first dose, according to figures from the Ministry of Health as of 23 August. “A very encouraging figure”, comments Professor Cohen, who receives these days “a lot of calls from parents decided to vaccinate their children” before the start of the school year. “They must be vaccinated to limit the circulation of the virus,” we told the Ministry of Health on Tuesday during the weekly briefing on vaccination. From September, campaigns are thus scheduled in schools.
However, vaccination is “not topical” for children under 12, recalled a few days ago the Minister of National Education Jean-Michel Blanquer. In mid-June, pediatricians did not recommend it for the youngest. But that was before the Delta tidal wave. “We were very mixed and recommended focusing on adults, but Delta has changed the situation,” confirms Professor Cohen, who fears that Covid-19 will turn into “a pediatric disease”, if the virus only circulates in the unvaccinated, therefore especially children.
Clinical studies underway on the vaccination of the youngest
However, “the severity of Covid-19 is not to be neglected” in children, insists Mircea Sofonea, highlighting the “5 to 20%” of long Covid, likely to also affect children, with symptoms “which may affect their quality of life or even have cognitive repercussions ”. “A British study estimates the proportion of children who have developed a long Covid at 4 to 8%,” adds Antoine Flahault. Without forgetting the pediatric multisystemic inflammatory syndrome (Pims), of which approximately 500 cases have been recorded in France since the appearance of Covid-19.
For Mircea Sofonea, with a more contagious and virulent Delta variant, according to Canadian and Scottish studies, there are clearly more benefits than before in also vaccinating the youngest. The American laboratories Pfizer and Moderna have already launched clinical studies on the vaccination of children under 12. Phase 2 and 3 trials [phases sur la tolérance et l’efficacité du vaccin, préalables à toute autorisation], the first results of which are expected at the end of the year at the earliest. The authorizations for use would therefore not be granted before 2022.