Low SARS-CoV-2 Prevalence, Transmission Risk in French Daycare Centers

(Reuters Health) – During the first French lockdown in 2020, few children or staff of French daycare centers had SARS-CoV-2 antibodies, suggesting the daycares were not major sites of virus transmission, according to a new study.

The analysis of seroprevalence data from 327 children and 197 staff in 22 daycare centers that remained open during the March through May lockdown found that just 6.8% of staff and 3.7% of kids were infected with the virus, and most cases were likely due to contact at home, according to the report published in The Lancet Child & Adolescent Health.

“Our results suggest that daycare centres are not focus points of SARS-CoV-2 virus infection and that young children are not spreading the virus widely in these environments,” the study’s senior author, Camille Aupiais of the Jean-Verdier Hospital, in Bondy, France, said in a statement. “These findings should be reassuring for parents who are keyworkers and are thought to be at higher risk during the first wave of the epidemic.”

The authors did not respond to a request for comment.

During the first French national lockdown, most daycare centers and schools were closed with a small number operating at reduced capacity, the authors note. Throughout this time, the daycare centers were advised to follow safety protocols which included working in smaller cohorts of six to eight children, disinfection of surfaces, use of facemasks, and social distancing. Parents were not allowed to enter the centers and were instructed to screen their children for COVID-19 symptoms before bringing them in.

The researchers performed a cross-sectional, multicenter seroprevalence study in 22 daycare centers in the Paris region and in the French cities of Annecy and Rouen in June of 2020, four to eight weeks after the end of the lockdown. The mean age of children was 1.9 years (range 5 months to 4.4 years). The researchers also analyzed seroprevalence among 197 adult daycare staff members and a comparison group of 164 hospital staff members working through the lockdown.

Positive serology tests were observed for 14 children (4.39%) and 14 daycare center staff (7.7%). After accounting for the imperfect sensitivity and specificity of the assay, the researchers estimated that 3.7% of the children and 6.8% of the daycare staff had been infected with SARS-CoV-2.

The comparator group of hospital staff members fared similarly to the daycare staff: nine had a positive serological test (5.5%), leading to a 5.0% seroprevalence after accounting for assay characteristics.

An exploratory analysis suggested that seropositive children (six of 14) were more likely than seronegative children (19 of 307) to have been exposed to an adult household member with laboratory-confirmed COVID-19 (relative risk 7.1).

Contact with a confirmed adult household case of COVID-19 during the lockdown – but not sibling cases or daycare peer cases – was more frequent in seropositive children than seronegative children, the study also found. In fact, 55% of seropositive children had at least one seropositive parent, versus 14% of seronegative children.

No difference was seen in seroprevalence rates between staff who were exposed (or not) to a child with confirmed COVID-19, the study team notes.

The results shed some light on the question of whether schools can safely open, said Dr. Aaron Milstone, a professor of pediatrics and infectious diseases at the Johns Hopkins School of Medicine, in Baltimore, who wasn’t involved in the study.

“Basic approaches seem to work,” Dr. Milstone said. “Some schools have done this successfully by keeping people masked and socially distanced. It seems that most infections are occurring in high risk settings – like Super Bowl parties, restaurants and bars – where people are not masked. But no place is zero risk.”

Even among healthcare workers it often wasn’t on the job that people were becoming infected, Dr. Milstone said. “What we have learned from interviewing hundreds and hundreds of healthcare workers is that it’s usually household contact,” he added. “A partner or a sick child at home or other high-risk activities like traveling somewhere or going to a bachelor party.”

SOURCE: https://bit.ly/3sfK9PB The Lancet Child & Adolescent Health, online February 8, 2021.

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