key: cord-0953102-eefk7bpf
authors: Viart, Juliette; Engelmann, Ilka; Joannes, Flora; Gras‐Le Guen, Christèle; Haas, Hervé; Chinazzo, Marie; Cantais, Aymeric; Gatin, Amélie; Brehin, Camille; Benhalima, Ilyes; Ouafi, Mahdi; Martinot, Alain; Dubos, François
title: A very low prevalence of SARS‐CoV‐2 infection but a high prevalence of other respiratory virus infections in children admitted to paediatric emergency departments
date: 2022-02-23
journal: Acta Paediatr
DOI: 10.1111/apa.16301
sha: e14bb50e3457c58cdad67d5da0ad94c18ff7b854
doc_id: 953102
cord_uid: eefk7bpf

AIM: To investigate the prevalence of infections by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) and other respiratory viruses among children admitted to paediatric emergency departments (PEDs). METHODS: From April to July 2020, a prospective, multicentre cohort study was conducted in the PEDs of eight French university hospitals. Regardless of the reason for admission, a nasopharyngeal swab sample from each child was screened using reverse transcription polymerase chain reaction tests for SARS‐CoV‐2 and other respiratory viruses. We determined the prevalence of SARS‐CoV‐2 and other respiratory viruses and identified risk factors associated with a positive test. RESULTS: Of the 924 included children (median [interquartile range] age: 4 years [1–9]; boys: 55%), 908 (98.3%) were tested for SARS‐CoV‐2. Only three samples were positive (0.3%; 95% confidence interval: 0.1–1) and none of these children had symptoms of coronavirus disease 2019. Of the 836 samples (90%) tested for other viruses, 129 (15.4%) were positive (primarily rhinovirus). Respiratory viruses were significantly more common in young children and in children with respiratory tract symptoms and fever. CONCLUSION: The prevalence of SARS‐CoV‐2 among children admitted to emergency departments was low. In contrast, and despite social distancing and other protective measures, the prevalence of other respiratory viruses detection was high.

Children have been considered as possible vectors for the dissemination of the new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), 1 as for other viral respiratory diseases. These assumptions prompted most governments to close schools during periods of lockdown in 2020. 2

Children with suggestive symptoms were less likely to be infected by the SARS-CoV-2 than adults during the first epidemic waves in China, Europe and the United States. 3-6 However, the estimated proportion of asymptomatic cases of COVID-19 among children in initial reports ranged from 9% to 16%. 7, 8 Children with mild or asymptomatic disease were suspected to be vectors for SARS-CoV-2.

Data on paediatric SARS-CoV-2 infection and transmission rates are often pooled and thus do not take account of the children's specific features and differences between age groups. The true prevalence of SARS-CoV-2 infection among children is therefore still subject to debate. 9 We assessed this prevalence among children admitted to paediatric emergency departments (PEDs). The prevalence of infections with other respiratory viruses was assessed for comparative data.

We conducted a prospective, multicentre cohort study in the PEDs at eight university hospitals in France: Lille, Nancy, Nantes, Nice, Paris-Colombes, Saint-Etienne, Toulouse and Tours. The study ran from April 15th to July 13th, 2020. The study was approved by an independent ethics committee (RCB-2020-A00811-38) and registered by the French National Data Protection Commission (DEC20-092). The primary objective was to determine the prevalence of SARS-CoV-2 detection in children. Secondary objectives were to determine the prevalence of SARS-CoV-2 and other viruses in children depending on the presence or not of suggestive symptoms of a SARS-CoV-2 infection, including respiratory tract symptoms.

The main inclusion criteria were age under 18, admission to one of the eight PEDs during office hours (regardless of the reason) and the provision of written informed consent for children over the age of 6 and from at least one parent. The main exclusion criteria were admission outside office hours, clotting disorders, absence of social security coverage or inability to communicate easily. The primary endpoint was a positive reverse transcriptase polymerase chain reaction (RT-PCR) test for SARS-CoV-2 in the child's nasopharyngeal swab. Secondary endpoints were a positive RT-PCR test for SARS-CoV-2 or other respiratory viruses among children without or with symptoms suggestive of SARS-CoV-2 infection.

A standardised questionnaire was filled out. Nasopharyngeal samples were collected using flocked swabs in 3 ml of viral transport medium (Yocon) and sent to the laboratory. The sample was either tested immediately, in cases of urgent result needed, or stored at −80°C. A follow-up phone call was made on days 7, 14 and 28 post-admission.

Immediately before RT-PCR, the specimens were thawed and heat inactivated for 30 min at 60°C. The Institut Pasteur Paris protocol of coronavirus disease 2019. Of the 836 samples (90%) tested for other viruses, 129 (15.4%) were positive (primarily rhinovirus). Respiratory viruses were significantly more common in young children and in children with respiratory tract symptoms and fever.

The prevalence of SARS-CoV-2 among children admitted to emergency departments was low. In contrast, and despite social distancing and other protective measures, the prevalence of other respiratory viruses detection was high. (https://www.who.int/docs/defau lt-sourc e/coron aviru se/real-timert-pcr-assay s-for-the-detec tion-of-sars-cov-2-insti tut-paste ur-paris.

pdf?sfvrs n=3662f cb6_2) was used with various commercial RT-PCR assays to detect SARS-CoV-2 ribonucleic acid (RNA) ( 

Our sample size calculation was based on the precision of the estimated prevalence and its 95% confidence interval (CI), using the (Table S4 ). 15 The prevalence of infection with other respiratory viruses appears to be lower in adults. One study reported a prevalence of 10.3% for other respiratory pathogens in a population of symptomatic patients with a suspected SARS-CoV-2 infection. 16 As in our study, the rhinovirus was predominant (31%). SARS-CoV-2 co-infections with other respiratory viruses were rare, in less than 3% of patients. 16, 17 The strength of our study was its prospective, multicentre design; this enabled us to screen children for both SARS-CoV-2 and other respiratory viruses, which has rarely been done before. The study was performed during and just after France's first period of lockdown in 2020, which can explain the low prevalence of the SARS-CoV-2 detection in our population. 18 At the time of the study, the prevalence rate was between 5% and 10% in the general population and then declined to a prevalence still over 1%. 19 Missing data was low for the required primary and secondary endpoints.

The low surface level of Angiotensin Conversion Enzyme-2 receptors for SARS-CoV-2 on the child's respiratory mucosa is probably one explication for the low infection and dissemination rates. 20 But this low prevalence may vary with a poor level of protective measures and the emergence of more contagious variants. In contrast, other respiratory viruses can easily colonise the respiratory tract in children. However, the transmission of all these viruses was reduced by social distancing measures. 21 Although the presence of influenza and coronavirus in respiratory droplets was dramatically reduced by the use of a surgical mask, rhinovirus could still be detected. 22 The social distancing measures might explain why the influenza epidemic was reduced in the northern hemisphere and did not occur in the southern hemispheres in 2020, 23 whereas epidemics of rhinovirus infections and RSV bronchiolitis did occur. 24 The absence of effective protective measures in young children is likely to result in the persistent circulation of seasonal respiratory viruses in this population. We expect the prevalence of these infections to vary with the extent and intensity of the protective measures that adults and older children will continue to apply.

Our study showed a low detection of SARS-CoV-2 in children admitted to the PEDs during and after the first lockdown in France.

However, despite distancing measures applied during this period, the detection of other respiratory viruses remained high, especially in young children with fever and respiratory tract symptoms. Similar studies will be required to follow the detection of SARS-CoV-2 in children with the emergence of new variants. TA B L E 1 Viruses identified in the 129 children with a positive multiplex reversetranscriptase polymerase chain reaction

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