Sociodemographic and Policy Factors Associated with the Transmission of COVID-19: Analyzing Longitudinal Contact Tracing Data from a Northern Chinese City.

To examine how sociodemographic characteristics and non-pharmaceutical interventions affect the transmission of COVID-19, we analyze patient profiles and contact tracing data from almost all cases in an outbreak in Shijiazhuang, China, from January to February 2021. Because of universal testing and digital tracing, the data are of high quality. Results from negative binomial models indicate that the counts of close contacts and secondary infections vary with the cases' age and occupation.

Prevalence and risk factors for pterygium: a cross-sectional study in Han and Manchu ethnic populations in Hebei, China.

Aims: To investigate the prevalence, ethnic differences and associated risk factors for pterygium in Han and Manchu populations aged 40-79 years in Hebei province, China.

Design: Cross-sectional study, as a part of the China National Health Survey.

Setting: Hebei province, China.

Mercury content in marketed cosmetics: analytical survey in Shijiazhuang, China.

Context: Mercury is one of the skin-lightening ingredients in cosmetics as mercury ions are thought to inhibit the synthesis of the skin pigment melanin in melanocyte cells.

Objective: The objective of this study was to evaluate the mercury levels of cosmetics currently marketed in Shijiazhuang, a northern city in China.

Methods: We collected 146 random cosmetic samples and analyzed for mercury concentrations or levels by cold vapor atomic absorption spectrometry.