ABSTRACT
IntroductionAdaptive immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) dynamics remain largely unknown. The neutralizing antibody (NAb) levels in patients with coronavirus disease 2019 (COVID-19) are helpful for understanding the pathology. Patients and MethodsUsing SARS-CoV-2 pseudotyped virus, serum sample neutralization values in symptomatic COVID-19 patients were measured using the chemiluminescence reduction neutralization test (CRNT). At least two sequential serum samples collected during hospitalization were analyzed to assess NAbs neutralizing activity dynamics at different time points. ResultsOf the 11 patients, four (36.4%), six (54.5%), and one (9.1%) had moderate, severe, and critical disease, respectively. Fifty percent neutralization (N50%-CRNT) was observed upon admission in 90.9% (10/11); all patients acquired neutralizing activity 2-12 days after onset. In patients with moderate disease, neutralization was observed at earliest within two days after symptom onset. In patients with severe-to-critical disease, neutralization activity increased, plateauing 9-16 days after onset. Neutralization activity on admission was significantly higher in patients with moderate disease than in patients with severe-to-critical disease (relative % of infectivity, 6.4% vs. 41.1%; P=.0011). ConclusionsNeutralization activity on admission inversely correlated with disease severity. The rapid NAb response may play a crucial role in preventing the progression of COVID-19.
ABSTRACT
ObjectiveThis study aimed to determine the frequency of SARS-CoV-2 RNA in serum and its association with the clinical severity of COVID-19. MethodsAn analytical cross-sectional study was performed in a single tertiary care hospital and included consecutive patients with confirmed COVID-19. The prevalence of SARS-CoV-2 RNAemia and the strength of its association with clinical severity variables, including required oxygen supplementation, ICU admission, invasive mechanical ventilation, and in-hospital mortality, were examined. ResultsFifty-six patients were included in the study. The median age was 54.5 years, and individuals with RNAemia were older than those without detectable SARS-CoV-2 RNA in serum (78 vs. 50 years; P = .0013). RNAemia was detected in 19.6% of patients (11/56) and in 1.0% (1/25), 50.0% (6/12), and 100.0% (4/4) of moderate, severe, and critically ill cases, respectively. Patients with RNAemia required more frequent oxygen supplementation (90.0% vs. 13.3%; P < .0001) and ICU admission (81.8% vs. 6.7%; P < .0001) and required invasive mechanical ventilation (27.3% vs. 0.0%; P < .0001). Among patients with RNAemia, the median viral loads of NP swabs that were collected around the same time as the serum were significantly higher in critically ill cases (5.4 Log10 copies/L [IQR: 4.2-6.3]) than in moderate-severe cases (2.6 Log10 copies/L [1.1-4.5]; P =.030) and were significantly higher in nonsurvivor cases (6.2 Log10 copies/L [IQR: 6.0-6.5]) than in survivor cases (3.9 Log10 copies/L [1.6-4.6]; P =.045). ConclusionsThis study demonstrated a relatively high proportion of SARS-CoV-2 RNAemia and an association between RNAemia and clinical severity. Moreover, among the patients with RNAemia, the viral loads of NP swabs were correlated with severity and mortality, thus suggesting the potential utility of combining serum testing with NP tests as a prognostic indicator for COVID-19 with a higher quality than each separate test.
ABSTRACT
To investigate the relationship between viral load and secondary transmission in novel coronavirus disease 2019 (COVID-19), we reviewed epidemiological and clinical data obtained from immunocompetent laboratory-confirmed patients with COVID-19 at Toyama University Hospital. In total, 28 patients were included in the analysis. Median viral load at the initial sample collection was significantly higher in adults than in children and in symptomatic than in asymptomatic patients. Among symptomatic patients, non-linear regression models showed that the estimated viral load at onset was higher in the index (patients who transmitted the disease to at least one other patient) than in the non-index patients (patients who were not the cause of secondary transmission; median [95% confidence interval]: 6.6 [5.2-8.2] vs. 3.1 [1.5-4.8] log copies/L, respectively). High nasopharyngeal viral loads around onset may contribute to secondary transmission of COVID-19. Article Summary LineHigh nasopharyngeal viral load around the onset may contributes to secondary transmission of COVID-19.
