Differences in humoral responses between children and adults
Multiplex systems analysis of antibody responses in saliva found
distinct SARS-CoV-2 specific antibody responses in infected children
compared to adults during the acute phase of infection (Figure 3A).
Three SARS-CoV-2 antibody features (IgA1 to Spike 1, IgA1 to
nucleocapsid protein (NP), IgA2 to NP, Figure 3B) were identified by
dimensionality reducing analysis (least absolute shrinkage and selection
operator (LASSO)) as significantly elevated responses in adult saliva
compared to children (Supplementary Figure 3, p =0.0023, p
<0.001, p <0.001 respectively), thus suggesting that
adults and children generate distinct mucosal antibody responses during
the acute phase of infection.
Given we observed different antibody profiles in the saliva between
adults and children, multiplex systems analysis was also conducted on
acute children and adult plasma samples. This analysis identified three
elevated antibody features that were unique to adult plasma (C1q Trimer
S C1q (Marker of antibody-mediated complement activation) to Trimer S,
IgG4 to RBD, IgA2 to NP, Supplementary Figure 4).
Secondary attack rate when including comprehensive virological and
antibody assessment Evidence of
SARS-CoV-2 exposure was observed in saliva and plasma antibody responses
in 62% of household contacts who tested negative by NPS (26/42: 7/42
serology, 24/42 saliva antibodies, Supplementary Figure 1). Therefore,
the secondary attack rate when respiratory (NPS) and non-respiratory
measures were included (saliva PCR, stool PCR, plasma antibodies, saliva
antibodies) was 76% (50/66). There was no onward transmission from
participants who tested negative by NPS, even if they were PCR positive
in other biological samples.