A SARS-CoV-2 variant B1.1.7 containing a mutation Δ69/70 has spread rapidly in the UK and shows an identifiable profile in ThermoFisher TaqPath RTqPCR (S-gene target failure; SGTF). We analysed recent test data for trends and significance . Linked Ct values for respiratory samples showed that a low Ct for ORF1ab and N were clearly associated with SGTF . Significantly more SGTF samples had higher inferred viral loads between 1x10 7 and 1x10 8 . Our conclusion is that patients whose samples exhibit the SGTF profile are more likely to have high viral loads, which may explain higher infectivity and rapidity of spread.