Association of epidemiological and clinical features with PCR cycle threshold values of SARS-CoV-2 infection: a cross-sectional study.

The cycle threshold (Ct) in quantitative real-time reverse-transcriptase polymerase chain reaction (qRT-PCR) is inversely correlated to the amount of viral nucleic acid or viral load and can be regarded as an indicator of infectivity. We examined the association of socio-demographic and clinical characteristics of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) polymerase chain reaction (PCR) positive cases with PCR cycle threshold (Ct) values at the time of diagnosis. SARS-CoV-2 cases reported between 12 October 2020 and 24 January 2021 in Regensburg were analyzed employing bivariate and multivariable methods. We included 3,029 SARS-CoV-2 cases (31% asymptomatic at diagnosis) and analyzed the association of case characteristics with Ct values in 2,606 cases. Among symptomatic patients, cough (38.0%), rhinitis (32.4%), headache (32.0), and fever/chills (29.9%) were the most frequent complaints. Ct values ≤20 were more frequent in symptomatic cases (20.9% vs. 11.3%), whereas Ct values >30 were more common in asymptomatic cases (32.6% vs. 18.0%). Ct values >20 and ≤30 were most common in symptomatic and asymptomatic cases (48.0% vs 40.7%). We observed lower median Ct values of E and N gene in symptomatic cases. In a random forest model, the total number of symptoms, respiratory symptoms, and age were most strongly associated with low Ct values. In conclusion, certain symptoms and age were associated with lower Ct values. Ct values can be used as a pragmatic approach in estimating infectivity at the first notification of a case and, thus, in guiding containment measures.

Clinical and epidemiological data of COVID-19 from Regensburg, Germany: a retrospective analysis of 1084 consecutive cases.

BACKGROUND: COVID-19 is a syndrome caused by the recently emerged SARS-CoV-2. We collected clinical and epidemiologic data in an almost complete cohort of SARS-CoV-2 positive individuals from Regensburg, Germany, from March 2020 to May 2020. METHODS: Analysis of a retrospectively documented cohort of consecutive COVID-19 cases recorded between March 7, 2020 and May 24, 2020 as part of an infection control investigation program, with prospective follow-up interviews gathering information on type and duration of symptoms and COVID-19 risk factors until June 26, 2020. RESULTS: Of 1089 total cases, 1084 (99.5%) cases were included. The incidence during the time period was 315.4/100,000, lower than in the superordinate government district Oberpfalz (468.5/100,000) and the overall state of Bavaria (359.7/100,000). The case fatality ratio (CFR) was 2.1%. Among fatal cases, the mean age was 74.4 years and 87% presented with known risk factors, most commonly chronic heart disease, chronic lung disease, kidney disease, and diabetes mellitus. 897 cases (82.7%) showed at least one symptom, most frequently cough (45%) and fever (41%). Further, 18% of cases suffered from odour/taste disorder. 17% of total cases reported no symptoms. The median duration of general illness was 10 days. During follow-up, 8.9% of 419 interviewed cases reported at least one symptom lasting at least 6 weeks, and fatigue was the most frequent persistent symptom. DISCUSSION: We report data on type and duration of symptoms, and clinical severity of nearly all (99.5%) patients with SARS-CoV-2 recorded from March 2020 to May 2020 in Regensburg. A broad range of symptoms and symptom duration was seen, some of them lasting several weeks in a considerable number of cases. The case-fatality ratio was 2.1%. Asymptomatic cases may be underrepresented due to the nature of the study.