Levels of SARS-CoV-2 RNA in the plasma and respiratory tract may explain why some patients with acute Covid-19 quickly recover, while others take longer, suggests a recent study published in Clinical Infectious Diseases.¹

Researchers from the United States set out to examine the correlation between the plasma and nasal SARS-CoV-2 RNA concentrations and symptom duration in 559 untreated, non-hospitalized adult patients with confirmed Covid-19 with onset of symptoms since ≤10 days and ongoing symptoms 48 hours before enrolment. The symptom score (median) at baseline was 10. They included the placebo recipients in the phase II/III multicenter Accelerating COVID-19 Therapeutic Interventions and Vaccines (ACTIV)-2/A5401 platform trial between August 2020 and July 2021 when the ancestral strain, alpha, and delta variants were the predominant circulating strains. The trial was conducted in the outpatient setting. Majority of the study subjects were unvaccinated and just 7% of them had taken the vaccine; 86% patients aged ≥55 years and those with comorbid conditions such as chronic lung disease, moderate to severe asthma, BMI >35 kg/m2, diabetes, hypertension, heart disease or chronic kidney/liver disease were at higher risk of progressing to severe infection.

SARS-CoV-2 was detected in plasma in 467 subjects at baseline, while 523 had anterior nasal SARS-CoV-2 RNA. Eighty-nine of the 467 patients in whom plasma RNA was detected presented with more severe symptoms when the study began. Participants with baseline anterior nasal RNA of ≥6 log10 copies/mL took 16 days for symptom improvement vs patients with ≤2 log10 copies/mL, whose symptoms improved in 9 days. Their symptoms also took longer time to resolve (25 vs 15 days). When the association of anterior nasal RNA and symptoms of acute Covid-19 was examined, resolution of cough and shortness of breath were delayed in patients with anterior nasal RNA of ≥6 log10 copies/mL with aHR of 0.63. However, fatigue or body ache resolved without delay. Among patients with detectable plasma SARS-CoV-2 RNA, resolution of cough (aHR 0.67), shortness of breath (aHR 0.67) and body pain (aHR 0.74) was delayed. No such association was observed for fatigue.

This analysis shows that resolution of acute Covid-19 symptoms is delayed in patients with SARS-CoV-2 viremia and high anterior nasal RNA levels. According to the authors, these findings suggest the potential use of nasal and plasma SARS-CoV-2 RNA levels as prognostic markers to assess duration of symptoms and predict recovery in acute Covid-19 patients being managed as outpatients.

Reference

1. Li Y, et al. Nasal and plasma SARS-CoV-2 RNA levels are associated with timing of symptom resolution in the ACTIV-2 trial of non-hospitalized adults with COVID-19. Clin Infect Dis. 2022 Oct 10;ciac818. doi: 10.1093/cid/ciac818.