This study compares the diagnostic performance of a nasopharyngeal swab antigenic test versus the RT-PCR Covid-19 reference test performed with the AllplexTM 2019-nCoV kit (Seegene, South Korea) in symptomatic children presenting at the hospital.

Since March 2020, France, like the rest of the world, has been suffering from the pandemic caused by SARS CoV-2, which has led to a considerable health crisis. Moreover, the scale of this epidemic was unexpected for the scientific community and the public authorities, who in fact had to find diagnostic and management solutions for COVID-19 most often in the short term. The reference diagnosis of COVID-19 is based on the RT-PCR technique, which allows diagnosis in the early stages of infectious manifestations.

However, since the French recommendations allow widely and without prescription the access the screening of individuals in biology laboratories, regardless of age, symptoms and history of COVID-19 contage, the delays in both the completion of these RT-PCR tests and the return of their results have increased and have become incompatible with relevant decision-making by the clinician and control of the epidemic.

Indeed, since the end of August 2020, it takes about ten days to get the result of an outpatient PCR test. With the increase in the circulation of the SARS-CoV2 virus and the number of positive cases in several regions of France, the use of rapid testing for SARS CoV-2 now seems essential.

Another diagnostic method of COVID-19 is the detection of specific SARS CoV-2 antigens in rhino-pharyngeal secretions and also allows early diagnosis. The qualitative detection of specific SARS CoV-2 antigens by immunochromatography, from rhino-pharynges samples, has the advantage of offering a result in about ten minutes. These tests use specific antibodies from SARS CoV-2 to selectively detect the S protein. Initially these tests like the one developed by the Belgian firm Coris Bioconcept were developed to identify positive COVID-19 patients. Thus, they could be used as rapid screening for screening and would be an alternative to RT-PCR. Their sensitivity varies according to manufacturers and especially according to the viral load between 60% and 90% with a specificity of more than 99%. The sensitivity of this test increases in patients with a high viral load, corresponding to a Ct 25.

In this context of active circulation of the virus and with a Positivity rate in RT-PCR of about 5% in children, it was important for us to evaluate the performance of a rapid diagnostic test by antigenic detection to optimize their management

Inclusion Criteria:

*Children under 18 years old requiring an RT-PCR Covid-19 defined according to the algorithm in force at CHI Créteil and which follows the recommendations of the GPIP and the SFP only for symptomatic children :

• Symptomatic children more then 6 years old: cough, and/or fever, and/or digestive disorders unless a diagnosis of another infectious disease is made with certainty (ex Scarlet fever, angina with AMS, enterovirus, urinary tract infections, chickenpox)
• Symptomatic children under 6 years old:

In case of hospitalization or symptoms severe enough to warrant further exploration.

Or who has had a proven contact with a COVID case. Or in contact at home with people considered at risk for SARS-CoV2 infection. Or whose symptoms do not improve after 3 days.

--Febrile children under 3 months old

• Express agreement of one of the parents present, the presence of only one of the two parents being recommanded in the current context
• Affiliated with the Social Security plan

Exclusion Criteria:

Refusal of one of the parents or child to participate in the protocol