Virological and Immunological Features of SARS-CoV-2 Infected Children Developing Specific and Neutralizing Antibodies

As the global COVID-19 pandemic progresses and with the school reopening, it is paramount to gain knowledge on adaptive immunity to SARS-CoV-2 in children in order to define possible immunization strategies and reconsider pandemic control measures. We analyzed anti-SARS-CoV-2 antibodies (Ab) and their neutralizing activity (PRNT) in 42 COVID-19-infected children 7 days after symptoms onset. Individuals with specific humoral responses presented faster virus clearance, and lower viral load associated to a reduced in vitro infectivity. We demonstrated that the frequencies of SARS-CoV-2 specific CD4-CD40L+ T-cells and Spike specific B-cells were associated with the anti-SARS-CoV-2 Ab and the magnitude of neutralizing activity. The plasma proteome confirmed the association between cellular and humoral SARS-CoV-2 immunity, with PRNT+ patients showing higher viral signal transduction molecules (SLAMF1, CD244, CLEC4G). This work shed lights on cellular and humoral anti-SARS-CoV-2 responses in children which may drive future vaccination trials endpoints and quarantine measures policies. Funding: This work was made possible by support from Bambino Gesu Children’s Hospital ricerca corrente 2020 to NC and ricerca corrente 2019 to PP, by PENTA and by Fondazione Cassa di Risparmio di Padova e Rovigo, Progetti di Ricerca Covid-19 (ADR participant). Conflict of Interest: The authors declare no competing interests. Ethical Approval: Local ethical committee approved the study and written informed consent was obtained from all participants or legal guardians.