ABSTRACT Importance . Antigen-based rapid diagnostic tests (RDTs) have shown good sensitivity for SARS-CoV-2 detection in adults and are used in children despite the lack data from children . Objective . We evaluated the diagnostic performance of the PanbioTM-COVID-19 Ag Rapid Test Device (P-RDT) in symptomatic and asymptomatic children against reverse-transcription polymerase chain reaction (RT-PCR) on nasopharyngeal swabs (NPS). Design . Prospective diagnostic study from 11.2020 to 03.2021 Setting . Single-center Participants . Consecutive symptomatic and asymptomatic participants 0-16yo Intervention . Two NPS for both RT-PCR and P-RDT Main outcome . P-RDT sensitivity and specificity Results . Eight-hundred and twenty-two participants completed the study, of which 533 (64.9 %) were symptomatic . Among the 119 (14.5 %) RT-PCR positive patients, the overall P-RDT sensitivity was 0.66 (95% CI 0.57-0.74). Mean viral load (VL) was higher among P-RDT positive than negative ones (p <0.001). Sensitivity was 0.87 in specimens with VL> 1.0E6 copies/mL (95% CI 0.87-1.00), which is the accepted cut-off for the presence of infectious virus, and decreased to 0.67 (95% CI 0.59-0.76) for specimens> 1.0E3 copies/mL . Among symptomatic participants, the P-RDT displayed a sensitivity of 0.73 (95% CI 0.64-0.82), which peaked at 1.00 at 2 days post onset of symptoms (DPOS; 95% CI 1.00-1.00), then decreased to 0.56 (95% CI 0.23-0.88) at 5 DPOS . There was a trend towards lower P-RDT sensitivity in symptomatic children <12 years (0.62 [95% CI 0.45-0.78] ) versus> 12 years (0.80 [95% CI 0.69-0.91]; p=0.09). VL which was significantly lower in asymptomatic participants than in symptomatic ones (p <0.001). The P-RDT displayed a sensitivity of 0.43 (95% CI 0.26-0.61). Specificity was 1.00 in symptomatic and asymptomatic children (95% CI 0.99-1.00). Conclusion and relevance . The overall respective 73% and 43% sensitivities of P-RDT in symptomatic and asymptomatic children was below the 80% cut-off recommended by the World Health Organization . These findings are likely explained by lower VLs in children at the time of diagnosis . As expected, we observed a direct correlation between VL and P-RDT sensitivity as well as variation of sensitivity according to DPOS, a major determinant of VL . These data highlight the limitations of RDTs both in symptomatic and asymptomatic children, with the potential exception in early symptomatic children> 12yrs where sensitivity reached 80 %.