Course of disease and related epidemiological parameters of COVID-19: a prospective study based on contact tracing cohort / 中华预防医学杂志

Objective: To analyze the course of disease and epidemiological parameters of COVID-19 and provide evidence for making prevention and control strategies. Methods: To display the distribution of course of disease of the infectors who had close contacts with COVID-19 cases from January 1 to March 15, 2020 in Guangdong Provincial, the models of Lognormal, Weibull and gamma distribution were applied. A descriptive analysis was conducted on the basic characteristics and epidemiological parameters of course of disease. Results: In total, 515 of 11 580 close contacts were infected, with an attack rate about 4.4%, including 449 confirmed cases and 66 asymptomatic cases. Lognormal distribution was fitting best for latent period, incubation period, pre-symptomatic infection period of confirmed cases and infection period of asymptomatic cases; Gamma distribution was fitting best for infectious period and clinical symptom period of confirmed cases; Weibull distribution was fitting best for latent period of asymptomatic cases. The latent period, incubation period, pre-symptomatic infection period, infectious period and clinical symptoms period of confirmed cases were 4.50 (95%CI:3.86-5.13) days, 5.12 (95%CI:4.63-5.62) days, 0.87 (95%CI:0.67-1.07) days, 11.89 (95%CI:9.81-13.98) days and 22.00 (95%CI:21.24-22.77) days, respectively. The latent period and infectious period of asymptomatic cases were 8.88 (95%CI:6.89-10.86) days and 6.18 (95%CI:1.89-10.47) days, respectively. Conclusion: The estimated course of COVID-19 and related epidemiological parameters are similar to the existing data.

Determination of zizybeoside II of Ziziphus jujuba by HPLC / 中国中药杂志

<p><b>OBJECTIVE</b>To develop a quantitative method for determination of zizybeoside II in Ziziphus jujuba.</p><p><b>METHOD</b>The samples were separated at 30 degrees C on a Zorbax SB-C18 column eluted with methanol-water (20 : 80) as the mobile phase. Flow rate was set at 1.0 mL x min(-1) and the detection wavelength was set at 210 nm.</p><p><b>RESULT</b>The calibration curve was linear within the range from 0.046 to 0.582 microg (r = 0.999 9) and the average recovery was 97.2%. 12 batches of the crude drugs purchased from different areas were determined and the contents of zizybeoside II in Fructus Jujubae were fluctuated from 0.013% to 0.041%.</p><p><b>CONCLUSION</b>The method is simple, repeatable and could be used for the quality control of Z. jujuba.</p>