Assessment of spread of SARS-CoV-2 by RT-PCR and concomitant serology in children in a region heavily affected by COVID-19 pandemic

Background

Several studies indicated that children seem to be less frequently infected with SARS-CoV-2 and potentially less contagious. To examine the spread of SARS-CoV-2 we combined both RT-PCR testing and serology in children in the most affected region in France, during the COVID-19 epidemic.

Methods

From April 14, 2020 to May 12, 2020, we conducted a cross-sectional prospective, multicenter study. Healthy controls and pauci-symptomatic children from birth to age 15 years were enrolled by 27 ambulatory pediatricians. A nasopharyngeal swab was taken for detection of SARS-CoV-2 by RT-PCR and a microsample of blood for micro-method serology.

Results

Among the 605 children, 322 (53.2%) were asymptomatic and 283 (46.8%) symptomatic. RT-PCR testing and serology were positive for 11 (1.8%) and 65 (10.7%) of all children, respectively. Only 3 children were RT-PCR–positive without any antibody response have been detected. The frequency of positivity on RT-PCR for SARS-CoV-2 was significantly higher in children with positive serology than those with a negative one (12.3% vs 0.6%, p<0.001). Contact with a person with proven COVID-19 increased the odds of positivity on RT-PCR (OR 7.8, 95% confidence interval [1.5; 40.7]) and serology (15.1 [6.6;34.6]).

Conclusion

In area heavily affected by COVID-19, after the peak of the first epidemic wave and during the lockdown, the rate of children with positive SARS-CoV-2 RT-PCR was very low (1.8%), but the rate of positive on serology was higher (10.7%). Most of PCR positive children had at the same time positive serology.

What is already known on this topic?

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  As compared with adults, children seem to be less frequently infected with SARS-CoV-2 and potentially less contagious according to several studies.

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  Most of the studies were based on RT-PCR SARS-CoV-2 testing, without antibody assays.

What this study adds?

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  This study combining RT-PCR and serologic testing, assessed the spread of SARS-CoV-2 infection in children in area heavily affected by COVID-19 pandemic.

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  Among a large cohort of children (>600), 11 (1.8%) were positive on RT-PCR for SARS-CoV-2 and 65 (10.7%) were positive on serology.

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  The only factor affecting positivity of RT-PCR for SARS-CoV-2 or serology was the household contact COVID-19.