Trends in SARS-CoV-2 cycle threshold values in the Czech Republic from April 2020 to April 2022.
Dita Musalkova, Lenka Piherova, Ondrej Kwasny, Zuzana Dindova, Lubor Stancik, Hana Hartmannova, Otomar Slama, Petra Peckova, Josef Pargac, Gabriel Minarik, Tomas Zima, Anthony J Bleyer, Martin Radina, Michal Pohludka, Stanislav Kmoch
Author Information
Dita Musalkova: Research Unit of Rare Diseases, Department of Paediatric and Adolescent Medicine, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic.
Lenka Piherova: Research Unit of Rare Diseases, Department of Paediatric and Adolescent Medicine, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic.
Ondrej Kwasny: SPADIA LAB, Ostrava, Czech Republic.
Hana Hartmannova: Research Unit of Rare Diseases, Department of Paediatric and Adolescent Medicine, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic.
Otomar Slama: Faculty of Safety Engineering, Technical University of Ostrava, Ostrava, Czech Republic.
Petra Peckova: Regional Authority of the Central Bohemia Region, Prague, Czech Republic.
Josef Pargac: SPADIA LAB, Ostrava, Czech Republic.
Gabriel Minarik: Medirex Group Academy, Trnava, Slovakia.
Tomas Zima: Institute of Medical Biochemistry and Laboratory Diagnostics, General University Hospital and the First Faculty of Medicine of Charles University, Prague, Czech Republic.
Anthony J Bleyer: Research Unit of Rare Diseases, Department of Paediatric and Adolescent Medicine, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic.
Martin Radina: SPADIA LAB, Ostrava, Czech Republic.
Michal Pohludka: GeneSpector, Prague, Czech Republic.
Stanislav Kmoch: Research Unit of Rare Diseases, Department of Paediatric and Adolescent Medicine, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic. skmoch@lf1.cuni.cz.
The inability to predict the evolution of the COVID-19 epidemic hampered abilities to respond to the crisis effectively. The cycle threshold (Ct) from the standard SARS-CoV-2 quantitative reverse transcription-PCR (RT-qPCR) clinical assay is inversely proportional to the amount of SARS-CoV-2 RNA in the sample. We were interested to see if population Ct values could predict future increases in COVID-19 cases as well as subgroups that would be more likely to be affected. This information would have been extremely helpful early in the COVID-19 epidemic. We therefore conducted a retrospective analysis of demographic data and Ct values from 2,076,887 nasopharyngeal swab RT-qPCR tests that were performed at a single diagnostic laboratory in the Czech Republic from April 2020 to April 2022 and from 221,671 tests that were performed as a part of a mandatory school surveillance testing program from March 2021 to March 2022. We found that Ct values could be helpful predictive tools in the real-time management of viral epidemics. First, early measurement of Ct values would have indicated the low viral load in children, equivalent viral load in males and females, and higher viral load in older individuals. Second, rising or falling median Ct values and differences in Ct distribution indicated changes in the transmission in the population. Third, monitoring Ct values and positivity rates would have provided early evidence as to whether prevention measures are effective. Health system authorities should thus consider collecting weekly median Ct values of positively tested samples from major diagnostic laboratories for regional epidemic surveillance.
References
N Engl J Med. 2020 Jun 11;382(24):2302-2315
[PMID: 32289214]
N Engl J Med. 2020 Mar 26;382(13):1194-1196
[PMID: 32074416]
