Summary Severe COVID-19 appears rare in children. This is unexpected, especially in young infants, who are vulnerable to severe disease caused by other respiratory viruses. We evaluate convalescent immune responses in 4 infants under 3 months old with confirmed COVID-19 who presented with mild febrile illness, alongside their parents, and adult controls recovered from confirmed COVID-19. Although not statistically significant, compared to seropositive adults, infants have high serum levels of IgG and IgA to SARS-CoV-2 spike protein, with a corresponding functional ability to block SARS-CoV-2 cellular entry. Infants also exhibit robust saliva anti-spike IgG and IgA responses. Spike-specific IFN-γ production by infant peripheral blood mononuclear cells appears restrained, but the frequency of spike-specific IFN-γ- and/or TNF-α-producing T cells is comparable between infants and adults. On principal-component analysis, infant immune responses appear distinct from their parents. Robust functional antibody responses alongside restrained IFN-γ production may help protect infants from severe COVID-19. Graphical abstract Highlights Distinct SARS-CoV-2 immune response of young infants compared with their parents High anti-spike IgG levels in sera and saliva of young infants Robust SARS-CoV-2 neutralization by sera of young infants Restrained spike-specific IFN-γ production by PBMCs of young infants Goenka et al. demonstrate that the SARS-CoV-2 immune response of young infants appears distinct compared with their parents. They show that infants exhibit relatively high serum (and saliva) levels of anti-spike IgG associated with robust SARS-CoV-2 neutralization but restrained cellular spike-specific IFN-γ production.
【저자키워드】 COVID-19, Immunity, antibody, Infant, T cell, 【초록키워드】 SARS-CoV-2, IgG, Saliva, immune response, severe COVID-19, children, Peripheral blood, serum, Infants, Adults, anti-Spike IgG, IgA, sera, SARS-CoV-2 spike protein, Control, Mild, PBMC, functional antibody response, cellular entry, convalescent, seropositive, SARS-CoV-2 neutralization, IFN-γ, cellular, Frequency, Analysis, severe disease, mononuclear cell, parents, Abstract, Serum level, help, parent, IgA responses, febrile illness, robust, PROTECT, evaluate, caused, functional, appear, comparable, statistically significant, anti-spike IgG level, the SARS-CoV-2, 【제목키워드】 SARS-CoV-2, functional antibody response, IFN-γ, robust,