Dynamics of disease characteristics and viral RNA decay in patients with asymptomatic and mild infections during the Omicron wave in Shanghai, China: A retrospective cohort study.

OBJECTIVES: Asymptomatic infections and mild diseases were more common during the Omicron outbreak in Shanghai, China in 2022. This study aimed to assess the characteristics and viral RNA decay between patients with asymptomatic and mild infections. METHODS: A total of 55,111 patients infected with SARS-CoV-2 who were quarantined in the National Exhibition & Convention Center (Shanghai) Fangcang shelter hospital within 3 days after diagnosis from April 9 to May 23, 2022 were enrolled. The kinetics of cycle threshold (Ct) values of reverse transcription-polymerase chain reaction were assessed. The influencing factors for disease progression and the risk factors for the viral RNA shedding time (VST) were investigated. RESULTS: On admission, 79.6% (43,852/55,111) of the cases were diagnosed with asymptomatic infections, and 20.4% were mild diseases. However, 78.0% of initially asymptomatic subjects developed mild diseases at the follow-up. The final proportion of asymptomatic infections was 17.5%. The median time of symptom onset, the duration of symptoms, and the VST were 2 days, 5 days, and 7 days, respectively. Female, age 19-40 years, underlying comorbidities with hypertension and diabetes, and vaccination were associated with higher risks of progressing to mildly symptomatic infections. In addition, mildly symptomatic infections were found to be associated with prolonged VST compared with asymptomatic infections. However, the kinetics of viral RNA decay and dynamics of Ct values were similar among asymptomatic subjects, patients with asymptomatic-to-mild infection, and patients with mild infection. CONCLUSION: A large proportion of initially diagnosed asymptomatic Omicron infections is in the presymptomatic stage. The Omicron infection has a much shorter incubation period and VST than previous variants. The infectivity of asymptomatic infections and mildly symptomatic infections with Omicron is similar.

SARS-CoV-2 Virus Dynamics in Recently Infected People-Data From a Household Transmission Study.

We used daily real-time reverse-transcription polymerase chain reaction (RT-PCR) results from 67 cases of SARS-CoV-2 infection in a household transmission study, conducted April 2020-May 2021, to examine the trajectory of cycle threshold (Ct) values, an inverse correlate of viral RNA concentration. Ct values varied across RT-PCR platforms and by participant age. Specimens collected from children and adolescents had higher Ct values and adults aged ≥50 years showed lower Ct values than adults aged 18-49 years. Ct values were lower on days when participants reported experiencing symptoms, with the lowest Ct value occurring 2-6 days after symptom onset.

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.

Lack of Prognostic Value of SARS-CoV2 RT-PCR Cycle Threshold in the Community.

The immense impact of the COVID-19 pandemic on health systems has motivated the scientific community to search for clinical prognostic factors for SARS-CoV-2 infection. Low cycle threshold values (Ct) of diagnostic real-time RT-PCR assays in hospitalized patients have been associated with a poor prognosis in several studies, whereas other studies did not find this association. We explored whether SARS-CoV-2 Ct values at diagnosis were associated with a poor outcome (admission to hospital and death) in 604 community patients diagnosed at primary health centers. Although lower Ct values were found in patients who died of COVID-19, the Ct value was not significantly associated with a worse outcome in a multivariate analysis, while age remained an independent prognostic factor. We did not find evidence to support the role of Ct values as a prognostic factor of COVID-19 in community cases.

Age and clinical signs as predictors of COVID-19 symptoms and cycle threshold value.

Many COVID-19 infected people remain asymptomatic, and hence the diagnosis at first presentation remains a challenge. Assessment at a presentation in primary care settings is usually done by visual triaging and basic clinical examination. This retrospective study involved investigating the medical e-records of COVID-19 positive patients who presented to a COVID-19 centre in Qatar for July 2020. The presence (symptomatic group) or the absence (asymptomatic group) of symptoms along with objective vital examination (ie; heart-rate (HR), temperature, haemoglobin saturation (SpO2)) were analysed and linked to the viral load (ie; cycle threshold (Ct)) of COVID-19 positive patients. Four hundred eighty-one symptomatic (230 males) and 216 asymptomatic (101 males) patients were included. Compared to the asymptomatic male group, the symptomatic male group was older, had lower Ct value and SpO2, and higher temperature and HR. Compared to the females asymptomatic group, the symptomatic females group had lower Ct value, and higher temperature. Compared to the asymptomatic group, the symptomatic group had lower Ct value and SpO2, and higher temperature and HR. Compared to the asymptomatic group, the symptomatic group had lower Ct values (age groups [21-30], [31-40], [41-50] and [51-60]), higher temperature (age groups [21-30] and [31-40], Ct ranges [20.01-25.00] and [25.01-30.00]), higher HR (age groups [21-30] and [31-40], Ct range [15.01-20.00]); and lower SpO2 (age groups [41-50] and [51-60], Ct ranges [15.01-20.00] and [35.01-40.00]). Compared with asymptomatic patients, symptomatic patients with COVID-19 are most likely to be febrile, tachycardic, hypoxic and having higher viral load. Higher viral load was associated with higher HR, higher temperature, lower SpO2, but there was no relation between viral load and age.

Asymptomatic transmission in the COVID-19 pandemic: A systematic review and meta-analysis

Objective To determine the differences in the epidemiological characteristics of asymptomatic patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and coronavirus disease 2019 (COVID-19) patients. Methods The relevant data of asymptomatic SARS-CoV-2 transmission literature in PubMed, Web of Science, CNKI, VIP medicine and Wanfang medical database were extracted as of August 1, 2020. Epidemiological information was screened and extracted according to pre-established inclusion and exclusion criteria. Age, gender, virus shedding duration and virual load of asymptomatic carriers were summarized and analyzed. Results A total of 38 articles met the criteria, 17 of which were asymptomatic case reports related to the virus shedding duration. Compared with symptomatic infected persons, asymptomatic individuals were younger [Weighted Mean Difference (WMD), WMD=-5.27, 95% CI: -9.78--0.76, P < 0.001] and the viral load was lower (WMD=2.36, 95% CI: 0.65-4.07, P=0.007). The virus shedding duration of asymptomatic individuals (median=11 days) was shorter than symptomatic patients (median=16 days). Conclusion Asymptomatic individuals with SARS-CoV-2 were younger, had a lower viral load and a shorter virus shedding duration than COVID-19 patients. © 2021, Publication Centre of Anhui Medical University. All rights reserved.

Correlation of hematological parameters and cycle threshold in ambulatory patients with SARS-CoV-2 infection.

INTRODUCTION: Former studies have shown that hematologic parameters are affected by the SARS-CoV-2 infection which has caused a global health problem. Therefore, this research aims to identify the most frequent symptoms and comorbidities in SARS-CoV-2 infected outpatients; besides, to analyze hematological parameters and their correlation with cycle threshold (Ct) values. METHODS: We analyzed a total of sixty outpatients with SARS-CoV-2 infection. They were divided according to sex. Afterward, a questionnaire was carried out to find out their symptoms and comorbidities. Additionally, blood biometry data were correlated with the Ct value, respectively. RESULTS: Sixty patients were analyzed; the mean age was 43 years. All patients were from Nayarit, Mexico. The frequency index showed that the main symptoms were headache and anosmia, and the comorbidities were obesity and smoking. The analysis of blood biometry showed a clear increase in red blood cells (RBC) related parameters in women. In both sexes an increase in the number of white blood cells (WBC) was observed. Also, all the hematological alterations correlated with the grade of infection. CONCLUSION: Headache and anosmia are the most common symptoms according to the frequency index, the main comorbidities were obesity and smoking. Also, there is a Ct value correlation with hematological parameters (WBC, mean corpuscular volume, mean corpuscular hemoglobin, hemoglobin); they can be used as a prognostic marker of infection.

Pretest Symptom Duration and Cycle Threshold Values for Severe Acute Respiratory Syndrome Coronavirus 2 Reverse-Transcription Polymerase Chain Reaction Predict Coronavirus Disease 2019 Mortality.

BACKGROUND: The relationship between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral load and patient symptom duration in both in- and outpatients, and the impact of these factors on patient outcomes, are currently unknown. Understanding these associations is important to clinicians caring for patients with coronavirus disease 2019 (COVID-19). METHODS: We conducted an observational study between March 10 and May 30, 2020 at a large quaternary academic medical center in New York City. Patient characteristics, laboratory values, and clinical outcomes were abstracted from the electronic medical records. Of all patients tested for SARS-CoV-2 during this time (N = 16 384), there were 5467 patients with positive tests, 4254 of which had available cycle threshold (Ct) values and were included in further analysis. Univariable and multivariable logistic regression models were used to test associations between Ct values, duration of symptoms before testing, patient characteristics, and mortality. The primary outcome is defined as death or discharge to hospice. RESULTS: Lower Ct values at diagnosis (ie, higher viral load) were associated with significantly higher mortality among both in- and outpatients. It is interesting to note that patients with a shorter time since the onset of symptoms to testing had a worse prognosis, with those presenting less than 3 days from symptom onset having 2-fold increased odds of death. After adjusting for time since symptom onset and other clinical covariates, Ct values remained a strong predictor of mortality. CONCLUSIONS: Severe acute respiratory syndrome coronavirus 2 reverse-transcription polymerase chain reaction Ct value and duration of symptoms are strongly associated with mortality. These 2 factors add useful information for clinicians to risk stratify patients presenting with COVID-19.

Is there a correlation between viral load and olfactory & taste dysfunction in COVID-19 patients?

OBJECTIVES: To evaluate the correlation between cycle threshold (Ct) value and occurrence of olfactory and taste dysfunction in COVID-19 patients. METHODS: This comparative study included COVID-19 patients diagnosed by reverse transcription- polymerase chain reaction (RT-PCR) based test at our hospital with mild to moderate disease. The demographic details and detailed clinical history of the patient, including history of loss of smell and taste was taken at the time of presentation. The patients were divided into 2 groups, group A: COVID-19 patients with OTD; group B: COVID-19 patients without OTD. 100 contiguous patients were recruited in each group. The COVID-19 test by RT-PCR was done and Ct value of the 3 genes: E (Envelope encoding) gene, N (Nucleocapsid encoding) gene, and RdRp (RNA-dependent RNA polymerase) gene, was used for data analysis. The Ct values of each of the three genes were compared between groups A and B. RESULTS: Group A and B did not differ significantly in terms of basic demographics. The differences in the Ct values of the 3 genes E gene, N gene and RdRp gene, of group A and B were found to be statistically significant (p = 0.005, p = 0.001 and p = 0.002, respectively). CONCLUSION: The patients with OTD had a lower Ct value at diagnosis, and hence, a higher viral load than those without OTD. The evaluation of Ct value and viral load in COVID-19 patients may help in further reducing the transmission of the virus in the community.

Time Length of Negativization and Cycle Threshold Values in 182 Healthcare Workers with Covid-19 in Milan, Italy: An Observational Cohort Study.

Background: Coronavirus Disease 2019 (COVID-19) has rapidly spread worldwide, becoming an unprecedented public health emergency. Rapid detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) suspected cases is crucial to control the spread of infection. We aimed to evaluate the time length of negativization from the onset of symptoms in healthcare workers (HCWs) with COVID-19, and to evaluate significant variations in cycle threshold (CT) values and gene positivity (E, RdRP, and N genes) among positive individuals who returned to work. Methods: We retrospectively analyzed a consecutive cohort of 182 SARS-CoV-2-positive HCWs in Milan, from 16 March to 30 April 2020. Nasopharyngeal swabs were tested by RT-PCR. Results: Asymptomatic HCWs were 17.6% (32/182), and 58 healed at 30 April 2020. The median time length of negativization was 4 weeks (35% of symptomatic versus 40% of asymptomatic HCWs). Four HCWs, healed at 30 April, turned positive within three weeks during controls set up in the work unit. Three-gene positivity had the greatest variability, and increasing CT values from single- to three-gene positivity among all age groups were observed. Conclusions: Self-isolation longer than two weeks and prolonged follow-up periods for the staff returning to work after COVID-19 could be the most suitable choices to counter the SARS-CoV-2 spread. Further studies are needed to investigate infectiousness profiles among positive individuals.