Acta Biomedica Scientifica (Apr 2021)

Viral Load in COVID-19: Underestimated Clinical and Epidemiological Marker

  • E. A. Orlova,
  • O. B. Ogarkov,
  • S. N. Zhdanova,
  • P. A. Khromova,
  • V. V. Sinkov,
  • M. A. Khasnatinov,
  • L. A. Rychkova,
  • L. I. Kolesnikova

DOI
https://doi.org/10.29413/ABS.2021-6.1.5
Journal volume & issue
Vol. 6, no. 1
pp. 33 – 39

Abstract

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Background. The viral load of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the new coronavirus infection, is becoming increasingly important in clinical and epidemiological contexts. Despite this, there are significant complexities in the implementation of viral load quantitative measurement into clinical practice due to the limited approaches to its assessment.The aim of this work was to develop an approach for SARS-CoV-2 viral load analysis by the value of sample threshold cycles (Ct) relative to the Ct of the internal control sample obtained in routine PCR diagnostics of the COVID-19, and to use this approach for quantitative monitoring of viral load in patients with first positive SARS-CoV-2 test from the Irkutsk region.Materials and methods. Using regression models based on the least squares method, an approach to determine the number of copies of SARS-CoV-2 RNA in 1 ml of nasopharyngeal secretion was developed. The viral load of SARS-CoV-2 was assessed in nasopharyngeal and pharyngeal samples obtained from 1370 patients from Irkutsk and Angarsk with primary diagnosed positive PCR result in the period from July 1 to November 10, 2020.Results. A tenfold increase in the average monthly viral load among patients in September-October 2020 was revealed. We assume that the change in the epidemiological pattern of the spread of the new coronavirus infection during this period is associated with an increase in the number of contacts in the population due to the school year beginning. Higher viral loads are observed in populations at risk for COVID-19 – among healthcare workers and adults/elderly patients. Conclusion. The development of a standardized quantification of SARS-CoV-2 viral load in the nasopharyngeal samples can be a predictive clinical marker and a reliable tool for improving COVID-19 surveillance using the proposed approach to assess average viral load in a local population.

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