ABSTRACT
BackgroundRapid spread of SARS-CoV-2 in Wuhan prompted heightened surveillance in Guangzhou and elsewhere in China. Modes of contact and risk of transmission among close contacts have not been well estimated. MethodsWe included 4950 closes contacts from Guangzhou, and extracted data including modes of contact, laboratory testing, clinical characteristics of confirmed cases and source cases. We used logistic regression analysis to explore the risk factors associated with infection of close contacts. ResultsAmong 4950 closes contacts, the median age was 38.0 years, and males accounted for 50.2% (2484). During quarantine period, 129 cases (2.6%) were diagnosed, with 8 asymptomatic (6.2%), 49 mild (38.0%), and 5 (3.9%) severe to critical cases. The sensitivity of throat swab was 71.32% and 92.19% at first to second PCR test. Among different modes of contact, household contacts were the most dangerous in catching with infection of COVID-19, with an incidence of 10.2%. As the increase of age for close contacts and severity of source cases, the incidence of COVID-19 presented an increasing trend from 1.8% (0-17 years) to 4.2% (60 or over years), and from 0.33% for asymptomatic, 3.3% for mild, to 6.2% for severe and critical source cases, respectively. Manifestation of expectoration in source cases was also highly associated with an increased risk of infection in their close contacts (13.6%). Secondary cases were in general clinically milder and were less likely to have common symptoms than those of source cases. ConclusionsIn conclusion, the proportion of asymptomatic and mild infections account for almost half of the confirmed cases among close contacts. The household contacts were the main transmission mode, and clinically more severe cases were more likely to pass the infection to their close contacts. Generally, the secondary cases were clinically milder than those of source cases.
ABSTRACT
To understand the relationship between visual impairment and risk of all-cause mortality in the elderly aged 65 years and older in 8 longevity areas in China. The data of the elderly aged 65 years and older in the project in 2012 were obtained from Healthy Aging and Biomarkers Cohort Study, a sub-cohort of the Chinese Longitudinal Healthy Longevity Survey, including physical measurement and survival status, and a follow-up for survival outcomes were conducted in 2014 and 2017 respectively. Cox proportional hazard regression model was used to analyze the influence of visual impairment on mortality. Gender and age specific analysis was conducted. A total of 1 736 elderly adults were included. A total of 943 deaths occurred during the 5-year follow-up period with a 5-year mortality rate of 54.3. The 5-year mortality rate was 76.7 in the group with visual impairment, and 47.6 in the group without visual impairment (<0.001). After adjusting for demographic information, life style and some disease factors, the risk of 5-year mortality in the group with visual impairment group was 1.30 times higher than that in the group without visual impairment (=1.30, 95: 1.09-1.55). In the females, the risk for mortality in the group with visual impairment was 1.48 times higher than that in the group without visual impairment (=1.48, 95:1.20-1.84). However, vision status was not associated with the risk for mortality in males (=1.02, 95: 0.72-1.43). The risk for mortality in the group with visual impairment was 1.39 times higher than that in the group without visual impairment in the elderly aged over 90 years (=1.39, 95: 1.13-1.70). Vision status was not associated with mortality risk in the elderly aged 65-79 years and 80-89 years (=1.37, 95: 0.61-3.07; =0.95, 95: 0.61-1.48). In the elderly people in China, visual impairment is a risk factor for mortality.
