CD40LG and COVID-19: The contribution to the assumption of protective mechanisms in children is the case of one 2 months old child, the subject of this study who was considered positive according to the epidemiological history due to a COVID-19 RT-PCR positive mother at birth, but found negative for both COVID - 19 (RT-PCR) as well as anti-SARS-CoV-2 antibodies (IgM, IgG).