Young infants exhibit robust functional antibody responses and restrained IFN-γ production to SARS-CoV-2
Anu Goenka, Alice Halliday, Michaela Gregorová, Emily Milodowski, Amy Thomas, Maia Kavanagh Williamson, Holly E. Baum, Elizabeth Oliver, Anna E. Long, Lea Knežević, Alistair J.K. Williams, Vito Lampasona, Lorenzo Piemonti, Kapil Gupta, Natalie Di Bartolo, Imre Berger, Ashley M. Toye, Barry Vipond, Peter Muir, Jolanta Bernatoniene, Mick Bailey, Kathleen M. Gillespie, Andrew D. Davidson, Linda Wooldridge, Laura Rivino, Adam Finn
Abstract
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.