Peripheral blood microRNAs and the COVID-19 patient: methodological considerations, technical challenges and practice points

RNA Biol. 2021 May;18(5):688-695. doi: 10.1080/15476286.2021.1885188. Epub 2021 Feb 15.


The COVID-19 emergency pandemic resulting from infection with SARS-CoV-2 represents a major threat to public health worldwide. There is an urgent clinical demand for easily accessible tools to address weaknesses and gaps in the management of COVID-19 patients. In this context, transcriptomic profiling of liquid biopsies, especially microRNAs (miRNAs), has recently emerged as a robust source of potential clinical indicators for medical decision-making. Nevertheless, the analysis of the circulating miRNA signature and its translation to clinical practice requires strict control of a wide array of methodological details. In this review, we indicate the main methodological aspects that should be addressed when evaluating the circulating miRNA profiles in COVID-19 patients, from preanalytical and analytical variables to the experimental design, impact of confounding, analysis of the data and interpretation of the findings, among others. Additionally, we provide practice points to ensure the rigour and reproducibility of miRNA-based biomarker investigations of this condition.Abbreviations: ACE: angiotensin-converting enzyme; ARDS: acute respiratory distress syndrome; COVID-19: coronavirus disease 2019; ERDN: early Detection Research Network; LMWH: low molecular weight heparin; miRNA: microRNA; ncRNA: noncoding RNA; SARS-CoV-2: severe acute respiratory syndrome coronavirus-2; SOP: standard operating procedure.

Keywords: Blood; COVID-19; RT-qPCR; SARS-CoV-2; biomarker; liquid biopsy; methods; microRNA; noncoding RNA.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • COVID-19 / blood*
  • COVID-19 / genetics*
  • COVID-19 / virology
  • Gene Expression Profiling / methods*
  • Gene Expression Profiling / standards
  • Genetic Markers
  • Humans
  • Liquid Biopsy / methods
  • Liquid Biopsy / standards
  • MicroRNAs / blood*
  • MicroRNAs / genetics*
  • MicroRNAs / isolation & purification
  • Pandemics
  • SARS-CoV-2*
  • Virus Inactivation


  • Genetic Markers
  • MicroRNAs

Grants and funding

This work was supported by the Instituto de Salud Carlos III [CIBERESUCICOVID, COV20/00110] cofunded by ERDF, “Una manera de hacer Europa.