Higher transmission vs lower transmission families
In 27% (7/26) of households, all family members tested positive by NPS
for SARS-CoV-2, which we have termed high transmission families
(families 3, 4, 6, 11, 12, 13, 20). High transmission families were
positive for most respiratory and non-respiratory samples (Supplementary
Figure 1). High transmission families were also largely characterised by
lower respiratory Ct-values than low transmission families
(Supplementary Figure 2A; High vs low transmission families; Median
22.62 vs 32.91; IQR 17.06 to 28.67 vs 30.37 to 34.24; p = 0.007).
Feature selection analysis identified antibody signatures associated
with lower Ct-values (Figure 1A-B). A heatmap including only these
selected antibody features illustrates that individuals from high
transmission households (green) generally had higher plasma antibody
responses to SARS-CoV-2 antigens (indicated by red heat signatures) and
clustered separately from the low transmission households which had
largely lower SARS-CoV-2 plasma antibody levels (indicated by blue
signatures). As before, this pattern of clustering between high and low
transmission families largely coincided with their differences in
measured Ct-values (low to high; white to purple) (Figure 1C).
Interestingly, all family members from 6/7 high transmission families
demonstrated evidence of neutralising antibodies as determined by
microneutralization assay (denoted by the asterisk on Supplementary
Figure 1). Furthermore, neutralising antibodies were only detected in
participants from high transmission families.