Population-level median cycle threshold (Ct) values for asymptomatic COVID-19 cases can predict the trajectory of future cases.

BACKGROUND: Recent studies indicate that the population-level SARS-CoV-2 cycle threshold (Ct) values can inform the trajectory of the pandemic. The presented study investigates the potential of Ct values in predicting the future of COVID-19 cases. We also determined whether the presence of symptoms could change the correlation between Ct values and future cases. METHODS: We examined the individuals (n = 8660) that consulted different sample collection points of a private diagnostic center in Pakistan for COVID-19 testing between June 2020 and December 2021. The medical assistant collected clinical and demographic information. The nasopharyngeal swab specimens were taken from the study participants and real-time reverse transcriptase polymerase chain reaction (RT-PCR) was used to detect SARS-CoV-2 in these samples. RESULTS: We observed that median Ct values display significant temporal variations, which show an inverse relationship with future cases. The monthly overall median Ct values negatively correlated with the number of cases occurring one month after specimen collection (r = -0.588, p <0.05). When separately analyzed, Ct values for symptomatic cases displayed a weak negative correlation (r = -0.167, p<0.05), while Ct values from asymptomatic cases displayed a stronger negative correlation (r = -0.598, p<0.05) with the number of cases in the subsequent months. Predictive modeling using these Ct values closely forecasted the increase or decrease in the number of cases of the subsequent month. CONCLUSIONS: Decreasing population-level median Ct values for asymptomatic COVID-19 cases appear to be a leading indicator for predicting future COVID-19 cases.

Factors associated with cycle threshold values (Ct-values) of SARS-CoV2-rRT-PCR.

BACKGROUND: Presented work studies the association of COVID-19 severity, patient demographics, and clinical history with cycle threshold (Ct) values of SARS CoV2-rRT-PCR. We studied the Ct values for Orf1ab, N, and RdRp genes in association with all the factors mentioned above. METHODS AND RESULTS: We examined the individuals (n = 6331) that consulted two private diagnostic centers for COVID-19 testing. SARS-CoV-2 was detected by RT-PCR assays using different commercial kits. Clinical and demographic information was collected by the attending health care professional. Ct values were not associated with the age, sex, or clinical history of the patient. Orf1ab and N genes Ct values were only weakly associated with symptoms at the time of the SARS-CoV-2 RT-PCR test. Also, the distributions of Ct values in SARS-CoV-2 positive patients are very similar irrespective of symptomatology. CONCLUSION: We conclude that the Ct values may have limitations in reliably predicting COVID-19 severity and should be used or reported with caution.

COVID-19 severity: Studying the clinical and demographic risk factors for adverse outcomes.

BACKGROUND: The primary goal of the presented cross-sectional observational study was to determine the clinical and demographic risk factors for adverse coronavirus disease 2019 (COVID-19) outcomes in the Pakistani population. METHODS: We examined the individuals (n = 6331) that consulted two private diagnostic centers in Lahore, Pakistan, for COVID-19 testing between May 1, 2020, and November 30, 2020. The attending nurse collected clinical and demographic information. A confirmed case of COVID-19 was defined as having a positive result through real-time reverse transcriptase polymerase chain reaction (RT-PCR) assay of nasopharyngeal swab specimens. RESULTS: RT-PCR testing was positive in 1094 cases. Out of which, 5.2% had severe, and 20.8% had mild symptoms. We observed a strong association of COVID-19 severity with the number and type of comorbidities. The severity of the disease intensified as the number of comorbidities increased. The most vulnerable groups for the poor outcome are patients with diabetes and hypertension. Increasing age was also associated with PCR positivity and the severity of the disease. CONCLUSIONS: Most cases of COVID-19 included in this study developed mild symptoms or were asymptomatic. Risk factors for adverse outcomes included older age and the simultaneous presence of comorbidities.