SARS-CoV-2 RT-PCR cycle threshold value and its association with disease severity and mortality among hospitalized pediatric COVID-19 patients

Objective@#This study determined the association of SARS-CoV-2 RT-PCR cycle threshold (Ct) value with disease severity and mortality among hospitalized pediatric COVID-19 patients.@*Methodology@#This is a retrospective cohort study of patients aged 0-18 years with SARS-CoV-2 RT-PCR-confirmed COVID-19 from 1-September-2020 to 31-August-2022. The cohort was divided into those with high (>30), medium (> 20) and low (</= 20) Ct values. Association between Ct values and disease severity was determined using Chi-square test and association between Ct values and mortality was determined using logistic regression.@*Results@#There were 236 patients included with male predominance. Median age was 7 years. Most belonged to the 0-5 years age group. Most were severe to critical COVID-19 cases. Median day of illness on swab collection was 4 days. Majority presented with symptoms such as fever (54%), cough (22%) and dyspnea (22%). Eighty-four percent had co-morbidities, of which majority were cancer and neurologic diseases. Median Ct value was 30.81. Fifty-four percent had high Ct values. The median age of patients with a high Ct value was significantly lower than other cohorts. The median day of illness of patients with low Ct value was significantly shorter than other cohorts. There was no significant difference across the terciles in terms of presence of co-morbidities. Majority of patients for each cohort had high Ct values. There was no significant association between Ct value and COVID-19 disease severity on admission. Nearly fifty percent had critical disease and the all-cause mortality rate was 21.61%. There was no significant association between Ct value and mortality.@*Conclusions@#Ct value was not associated with disease severity and all-cause mortality after controlling for confounders. A look into medical interventions, emergence of variants, and other factors that may affect the clinical presentation, disease course, severity and outcome are recommended in future studies.

Trajectory and impact factors of cycle threshold values of virus load in respiratory tract in children infected with severe acute respiratory syndrome coronavirus 2 Omicron variants / 中华传染病杂志

Objective:To investigate the clinical characteristics of children infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variants, and the impact factors of duration of cycle threshold (Ct) values turning to ≥35 detected by nucleotide test.Methods:Children aged 0 to 14 years with clinical symptoms of Omicron variants infection who admitted to designated hospital in Shanghai City (Renji Hospital, South Branch, Shanghai Jiao Tong University School of Medicine) from April 7 to June 2, 2022 were enrolled. The daily nasopharyngeal swab specimens were used for SARS-CoV-2 nucleic acid detecting by polymerase chain reaction and the results were expressed as Ct values. The T Ct≥ x was defined as from the symptom onset or first positive nucleic acid test results (the earlier data) to Ct≥ x of the open reading frame 1ab ( ORF1 ab) gene, which was the time duration from the initial to a specific Ct value.Clinical data were collected, including age, sex, vaccination and comorbidities.Cox model was performed to analyzed the impact factors of T Ct≥35. Results:A total of 871 pediatric cases with a median age of two years (ranging from one month to 14 years old) were included. Among them, 474 cases (54.4%) were male, and 89 cases (10.2%) had underlying diseases including congenital heart disease, solid tumors and epilepsy. There were 572(65.7%) mild cases, 298(34.2%) common cases, one (0.1%) severe case and no critical cases or deaths. The T Ct≥35 was 12(10, 14) days. Cox model indicated that compared to children aged one to 12 months, children aged 37 to 84 months and 85 to 168 months had shorter T Ct≥35 (hazard ratio ( HR)=1.55 and 1.84, respectively, both P<0.001). After adjusted with age, comparing to unvaccinated patients, patients with one or two shots vaccine had shorter T Ct≥35 (adjected hazard ratio (a HR)=1.49, P=0.011), and common patients had longer T Ct≥35 than mild patients (a HR=0.78, P=0.002), and patients with comorbidities had longer T Ct≥35than patients without comorbidities (a HR=0.38, P<0.001).The duration of T Ct≥28, T Ct≥30, T Ct≥33 and T Ct≥35 in children without underlying diseases were 7(6, 9) d, 9(7, 10) d, 10(8, 11) d and 12(10, 14) d, respectively. Conclusions:Age, vaccination, disease severity and underlying diseases could affect the duration of SARS-CoV-2 nucleotide turning to negative (Ct value≥35) in children infected with Omicron variants.

SARS CoV2 RT-PCR cycle threshold (Ct) values and the risk of developing acute respiratory distress syndrome in patients with Covid19

Background. SARS-CoV-2 viral loads may aid in the risk stratification of patients with COVID-19. Methods. 486 patients tested positive for SARS Cov2 by real time RT-PCR were included in this study. All the tests were performed on nasopharyngeal swabs during the first week after symptom onset using Sansure Biotech™ SARS Cov2 real time RT-PCR kits. Patient's condition was monitored over a period of one month after the onset of symptoms. Results. The mean Ct value in the group of patients who developed acute respiratory distress syndrome (ARDS +) was 18.27 (95% CI: 17.43-19.10) while for the ARDS group it was 33.06 (95% CI: 32.77-33.34). Discussion. The Ct values in the group of patients who developed ARDS (ARDS +) were significantly lower than those observed in the ARDS- group. By setting a cut-off value, the determination Ct values (on a qualitative technique) from nasopharyngeal swabs performed during the first week after symptom onset will assist clinicians in risk-stratifying patients. Conclusion. Our data show that the determination of SARS CoV2 RTPCR cycle threshold values from nasopharyngeal swabs performed during the first week after symptom onset may aid in the risk stratification of patients with COVID-19

Study on the effects of hemolysis, fatty blood and various storage conditions on HBV DNA,HIV RNA nucleic acid screening / 天津医药

Objective To study the influences of hemolysis, fatty blood, storage temperature and storage time on blood HIV RNA and HBV DNA. Methods The HBV DNA and HIV RNA samples (the concentration was 12-30 times of limit of detection of reagent), which were stored for 4 h, 1 d, 3 d,1 w and 4 w under the conditions of 4℃, 25℃, 37℃and-30℃, were detected using Roche MPX V2.0 kit. The HBV DNA and HIV RNA samples (the concentration was 2-5 times of limit of detection of reagent) were detected by the 6 groups of hemolytic samples (the concentrations of hemoglobin were 97 g/L, 34 g/L,17 g/L, 8 g/L, 5 g/L and 3 g/L, respectively). NAT test was performed at 5-group lipid samples (the concentrations of triglyceride were 7.93 mmol/L, 3.80 mmol/L, 2.63 mmol/L, 1.83 mmol/L and 1.49 mmol/L, respectively) and the control group samples (the concentrations of hemoglobin and triglyceride were 0 g/L and 0.95 mmol/L respectively). Results There were no significant differences in Ct values of HIV RNA or HBV DNA between 4 h to 4 w at 25℃(P>0.05). There were significant differences in Ct values of HBV DNA after preservation for 3 d and 1 w under 37 ℃ compared with those of preservation for 4 h,1 d and 2 d (P<0.005). When Hb concentration was reached to 97 g/L, the results of HBV DNA and HIV RNA were negative. When the concentration of Hb was less than 34 g/L, compared with the control group, there were no significant differences in Ct values of HIV RNA and HBV DNA (P>0.05). When the TG concentration was≤7.93 mmol/L, there were no significant differences in Ct values between the control group and the TG group (P>0.05). Conclusion The samples of HIV RNA and HBV DNA detected by Roche MPX V2.0 kit can be stored at room temperature (25℃) for four weeks. When the concentrations of TG and Hb are less than 7.93 mmol/L and 34 g/L respectively, there are no effects on HIV RNA or HBV DNA samples detected by Roche MPX V2.0 kit.

Study on the effects of hemolysis, fatty blood and various storage conditions on HBV DNA,HIV RNA nucleic acid screening / 天津医药

Objective To study the influences of hemolysis, fatty blood, storage temperature and storage time on blood HIV RNA and HBV DNA. Methods The HBV DNA and HIV RNA samples (the concentration was 12-30 times of limit of detection of reagent), which were stored for 4 h, 1 d, 3 d,1 w and 4 w under the conditions of 4℃, 25℃, 37℃and-30℃, were detected using Roche MPX V2.0 kit. The HBV DNA and HIV RNA samples (the concentration was 2-5 times of limit of detection of reagent) were detected by the 6 groups of hemolytic samples (the concentrations of hemoglobin were 97 g/L, 34 g/L,17 g/L, 8 g/L, 5 g/L and 3 g/L, respectively). NAT test was performed at 5-group lipid samples (the concentrations of triglyceride were 7.93 mmol/L, 3.80 mmol/L, 2.63 mmol/L, 1.83 mmol/L and 1.49 mmol/L, respectively) and the control group samples (the concentrations of hemoglobin and triglyceride were 0 g/L and 0.95 mmol/L respectively). Results There were no significant differences in Ct values of HIV RNA or HBV DNA between 4 h to 4 w at 25℃(P>0.05). There were significant differences in Ct values of HBV DNA after preservation for 3 d and 1 w under 37 ℃ compared with those of preservation for 4 h,1 d and 2 d (P<0.005). When Hb concentration was reached to 97 g/L, the results of HBV DNA and HIV RNA were negative. When the concentration of Hb was less than 34 g/L, compared with the control group, there were no significant differences in Ct values of HIV RNA and HBV DNA (P>0.05). When the TG concentration was≤7.93 mmol/L, there were no significant differences in Ct values between the control group and the TG group (P>0.05). Conclusion The samples of HIV RNA and HBV DNA detected by Roche MPX V2.0 kit can be stored at room temperature (25℃) for four weeks. When the concentrations of TG and Hb are less than 7.93 mmol/L and 34 g/L respectively, there are no effects on HIV RNA or HBV DNA samples detected by Roche MPX V2.0 kit.