Impact of baseline SARS-CoV-2 load in plasma and upper airways on the incidence of acute extrapulmonary complications of COVID-19: a multicentric, prospective, cohort study

Background Extrapulmonary complications (EPCs) are common in patients hospitalized for COVID-19, but data on their clinical consequences and association with viral replication and systemic viral dissemination is lacking. Methods Patients hospitalized for COVID-19 and enrolled in the TICO (Therapeutics for Inpatients with COVID-19) platform trial at 114 international sites between August 2020 and November 2021 were included in a prospective cohort study. We categorized EPCs into 39 event types within 9 categories and estimated their frequency through day 28 and their association with clinical outcomes through day 90. We analyzed the association between baseline viral burden (plasma nucleocapsid antigen [N-Ag] and upper airway viral load [VL]) and EPCs, adjusting for other baseline factors. Results 2,625 trial participants were included in the study. The median age was 57 years (IQR 46-68), 57.7% were male, and 537 (20.5%) had at least one EPC. EPCs were associated with higher day-90 all-cause mortality (HR 9.6, 95% CI 7.3, 12.7) after adjustment for other risk factors. The risk of EPCs increased with increasing baseline plasma N-Ag (HR 1.21 per log10 ng/L increase, 95% CI 1.09, 1.34), and upper airway VL (HR 1.12 per log10 copies/mL increase, 95% CI 1.04, 1.19), after adjusting for comorbidities, disease severity, inflammatory markers, and other baseline factors. Trial treatment allocation had no effect on EPC risk. Conclusions Systemic viral dissemination as evidenced by high plasma N-Ag and high respiratory viral burden are associated with development of EPCs in COVID-19, which in turn are associated with higher 90-day mortality.