SARS-CoV-2 Viral Load and Cytokine Dynamics Profile as Early Signatures of Long COVID Condition in Hospitalized Individuals.

Background: The global pandemic caused by SARS-CoV-2 has resulted in millions of people experiencing long COVID condition, a range of persistent symptoms following the acute phase, with an estimated prevalence of 27%-64%.

Materials And Methods: To understand its pathophysiology, we conducted a longitudinal study on viral load and cytokine dynamics in individuals with confirmed SARS-CoV-2 infection. We used reverse transcriptase droplet digital PCR to quantify viral RNA from nasopharyngeal swabs and employed multiplex technology to measure plasma cytokine levels in a cohort of people with SARS-CoV-2 infection. Our study included individuals with long COVID condition and those without, all of whom had at least three nasopharyngeal and plasma samples collected within 55 days after diagnosis of SARS-CoV-2 infection.

Results: Individuals affected with long COVID symptoms had delayed viral clearance and lower viral loads at diagnosis compared to those without symptoms. Additionally, cytokine analysis revealed variations in IL-18, MIG, and IP-10 levels, with delayed normalization in individuals affected by long COVID syndrome. Correlation analysis indicated associations between viral load and IP-10 and interrelations among cytokines IL-1β, IL-18, MIG, and IP-10.

Conclusion: Our study provides insights into the association between nasopharyngeal viral load, cytokine dynamics, and the development of long COVID syndrome, providing an early signature of this condition.