S-variant SARS-CoV-2 lineage B1.1.7 is associated with significantly higher viral loads in samples tested by ThermoFisher TaqPath RT-qPCR

Research output: Contribution to journalArticlepeer-review


  • M Kidd
  • A Best
  • N Cumley
  • B Percival
  • M Mayhew
  • O Megram
  • T White
  • E Moles-Garcia
  • L Crawford
  • A Bosworth
  • SF Atabani
  • Tim Plant


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.


Original languageEnglish
JournalThe Journal of Infectious Diseases
Publication statusE-pub ahead of print - 13 Feb 2021


  • SARS-CoV-2, COVID-19, RT-PCR, TaqPath, viral load, Ct values, Δ69/70, S-variant, B.1.1.7, VUI-202012/01, SGTF, S-gene dropout