As the global COVID-19 pandemic progresses, it is paramount to gain knowledge on adaptive immunity to SARS-CoV-2 in children to define immune correlates of protection upon immunization or infection. We analyzed anti-SARS-CoV-2 antibodies and their neutralizing activity (PRNT) in 66 COVID-19-infected children at 7 (±2) days after symptom onset. Individuals with specific humoral responses presented faster virus clearance and lower viral load associated with 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 antibodies and the magnitude of neutralizing activity. The plasma proteome confirmed the association between cellular and humoral SARS-CoV-2 immunity, and PRNT + patients show higher viral signal transduction molecules (SLAMF1, CD244, CLEC4G). This work sheds lights on cellular and humoral anti-SARS-CoV-2 responses in children, which may drive future vaccination trial endpoints and quarantine measures policies.

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About one-third of vertically HIV-1 infected infants develop AIDS within the first months of life; the remainder show slower disease progression. We investigated the relationship between the pattern of HIV-1 replication early in life and disease outcome in eleven infected infants sequentially studied from birth. Viral load in cells and plasma was measured by highly sensitive competitive PCR-based methods.Although all infants showed an increase in the indices of viral replication within their first weeks of life, three distinct patterns emerged: ( a ) a rapid increase in plasma viral RNA and cell-associated proviral DNA during the first 4-6 wk, reaching high steady state levels ( Ͼ 1,000 HIV-1 copies/10 5 PBMC and Ͼ 1,000,000 RNA copies/ml plasma) within 2-3 mo of age; ( b ) a similar initial rapid increase in viral load, followed by a 2.5-50-fold decline in viral levels; ( c ) a significantly lower ( Ͼ 10-fold) viral increase during the first 4-6 wk of age. All infants displaying the first pattern developed early AIDS, while infants with slower clinical progression exhibited the second or third pattern.These findings demonstrate that the pattern of viral replication and clearance in the first 2-3 mo of life is strictly correlated with, and predictive of disease evolution in vertically infected infants. ( J. Clin. Invest. 1996. 97:323-330.)

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