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.