A novel coronavirus disease, designated as COVID-19, has become a pandemic worldwide. This study aims to estimate the incubation period and serial interval of COVID-19. We collected contact tracing data in a municipality in Hubei province during a full outbreak period. The date of infection and infector–infectee pairs were inferred from the history of travel in Wuhan or exposed to confirmed cases. The incubation periods and serial intervals were estimated using parametric accelerated failure time models, accounting for interval censoring of the exposures. Our estimated median incubation period of COVID-19 is 5.4 days (bootstrapped 95% confidence interval (CI) 4.8–6.0), and the 2.5th and 97.5th percentiles are 1 and 15 days, respectively; while the estimated serial interval of COVID-19 falls within the range of −4 to 13 days with 95% confidence and has a median of 4.6 days (95% CI 3.7–5.5). Ninety-five per cent of symptomatic cases showed symptoms by 13.7 days (95% CI 12.5–14.9). The incubation periods and serial intervals were not significantly different between male and female, and among age groups. Our results suggest a considerable proportion of secondary transmission occurred prior to symptom onset. And the current practice of 14-day quarantine period in many regions is reasonable.

This study aimed to investigate the expression and diagnostic value of miR-106b-5p in asymptomatic carotid artery stenosis (CAS) patients, and further explore its predictive value for the occurrence of cerebral ischemic events (CIE). A total of 58 asymptomatic CAS cases and 61 healthy controls were recruited. Quantitative RT-PCR was applied for the measurement of the miR-106b-5p level. The receiver operating characteristic (ROC) curve was plotted to assess the diagnostic value of miR-106b-5p for CAS. Kaplan–Meier methods and Cox regression analysis were performed to assess the predictive value of miR-106b-5p for the occurrence of CIE. In patients with asymptomatic CAS, miR-106b-5p was highly expressed. The miR-106b-5p level showed a significant association with dyslipidemia, hypertension, and the degree of carotid stenosis. miR-106b-5p had a relative accuracy in differentiating patients with asymptomatic CAS from healthy individuals, with a sensitivity of 89.7% and specificity of 83.6% at the cutoff value of 0.198. Patients with high miR-106b-5p expression experienced more CIE. miR-106b-5p was highly expressed in patients with asymptomatic CAS. Our present results provide evidence for miR-106b-5p as a promising biomarker for CAS diagnosis, and for predicting the risk of future CIE in patients with asymptomatic CAS.

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