Viral RNA Load in Symptomatic and Asymptomatic COVID-19 Omicron Variant-Positive Patients.

Objectives: Viral load is important when evaluating viral transmission potential, involving the use of a polymerase chain reaction (PCR) cycle threshold (Ct) value. We aimed to analyze the PCR Ct values of respiratory tract samples taken from patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant strains to evaluate these strains' viral dynamics. Methods: This study comprised 361 patients. The Ct values of SARS-CoV-2-related respiratory samples were compared between symptomatic and asymptomatic patients. Results: The median (25th percentile and 75th percentile) nasopharynx and oropharynx SARS-CoV-2 Ct values were 30.5 (24.5-35.0) and 34.5 (30.0-37.0) in the symptomatic group, respectively, and 27.8 (23.4-34.5) and 33.5 (26.0-35.0) in the asymptomatic group, respectively, without significance. In the symptomatic group, subgroup analyses according to age showed the mean nasal Ct value for patients aged >18 years was 29.0 (23.5-34.5), which was significantly lower than that of patients aged 0-4 years and 5-13 years (36.0 (30.5-38.0) and 34.5 (31.0-39.0), respectively). The nasal Ct value for asymptomatic patients aged >18 years was 25.5 (20.9-28.4), which was significantly lower than of patients aged 5-13 years (34.5 (25.6-36.4)). Conclusion: Our findings suggest that the viral loads of asymptomatic and symptomatic patients did not differ significantly. However, adults infected with SARS-CoV-2 had higher nasal viral loads that those of young children.

Course and clinical severity of the SARS-CoV-2 Omicron variant infection in Tianjin, China (preprint)

There is limited information describing the course and severity of illness in subjects infected by the SARS-CoV-2 Omicron variant, especially in children. In this population-based cohort study, subjects with Omicron variant infection during the outbreak between January 8 and February 12, 2022 in Tianjin, China were included. The main outcomes were the distribution of illness severity and clinical courses. Of the 429 subjects (113 [26.3%] children; 239 [55.7%] female; median age, 36 years [IQR 15.0 to 55.0 years]), the proportion (95% CI) of symptomatic subjects on admission was 95.6% (93.2%, 97.2%), including 60.4% (55.7%, 64.9%) mild, 35.0% (30.6%, 39.6%) moderate, and 0.2% (0.0%, 1.3%) severe. Compared with adults, children had lower proportion of moderate Covid-19 (8.8% vs 44.3%). The median (IQR) length of hospital stay was 14.0 (12.0, 15.0) days. Symptomatic and moderate Covid-19 in Omicron infections was common in adults and children.