Risk for transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to close contacts of infected persons has not been well estimated. To evaluate the risk for transmission of SARS-CoV-2 to close contacts in different settings. Prospective cohort study. Close contacts of persons infected with SARS-CoV-2 in Guangzhou, China. 3410 close contacts of 391 index cases were traced between 13 January and 6 March 2020. Data on the setting of the exposure, reverse transcriptase polymerase chain reaction testing, and clinical characteristics of index and secondary cases were collected. Measurement: Coronavirus disease 2019 (COVID-19) cases were confirmed by guidelines issued by China. Secondary attack rates in different settings were calculated. Among 3410 close contacts, 127 (3.7% [95% CI, 3.1% to 4.4%]) were secondarily infected. Of these 127 persons, 8 (6.3% [CI, 2.1% to 10.5%]) were asymptomatic. Of the 119 symptomatic cases, 20 (16.8%) were defined as mild, 87 (73.1%) as moderate, and 12 (10.1%) as severe or critical. Compared with the household setting (10.3%), the secondary attack rate was lower for exposures in healthcare settings (1.0%; odds ratio [OR], 0.09 [CI, 0.04 to 0.20]) and on public transportation (0.1%; OR, 0.01 [CI, 0.00 to 0.08]). The secondary attack rate increased with the severity of index cases, from 0.3% (CI, 0.0 to 1.0%) for asymptomatic to 3.3% (CI, 1.8% to 4.8%) for mild, 5.6% (CI, 4.4% to 6.8%) for moderate, and 6.2% (CI, 3.2% to 9.1%) for severe or critical cases. Index cases with expectoration were associated with higher risk for secondary infection (13.6% vs. 3.0% for index cases without expectoration; OR, 4.81 [CI, 3.35 to 6.93]). There was potential recall bias regarding symptom onset among patients with COVID-19, and the symptoms and severity of index cases were not assessed at the time of exposure to contacts. Household contact was the main setting for transmission of SARS-CoV-2, and the risk for transmission of SARS-CoV-2 among close contacts increased with the severity of index cases. Guangdong Province Higher Vocational Colleges and Schools Pearl River Scholar Funded Scheme.

Background: Rapid 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. Methods: We 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. Results: Among 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. Conclusions: In 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.

High‐sensitivity C‐reactive protein (hs‐CRP) and lipoprotein‐associated phospholipase A2 (Lp‐PLA2) have been reported to be independent predictors of atherosclerosis. However, whether the combination of these two markers can improve the prediction of atherosclerosis is unknown. This study aimed to evaluate the association between combining hs‐CRP and Lp‐PLA2 and predicting carotid atherosclerosis. A total of 1982 participants aged ≥40 years were included in this study. Hs‐CRP and Lp‐PLA2 were measured by a high‐sensitivity nephelometry assay and quantitative sandwich enzyme‐linked immunosorbent assay, respectively. Ultrasonography was performed on the bilateral carotid arteries to evaluate stenosis and plaques. Multivariable logistic regression models were used to analyse the association between the combination of the hs‐CRP and Lp‐PLA2 levels and carotid plaques and stenosis. A total of 1579 (79.7%) and 181 (9.1%) subjects had carotid plaques and carotid stenosis, respectively. The group with high hs‐CRP and Lp‐PLA2 levels had the highest prevalence of carotid plaques (90.6%) and stenosis (20.8%). A significant association was found between high hs‐CRP and Lp‐PLA2 levels and carotid stenosis (adjusted odds ratio [OR]: 2.39; 95% confidence interval [CI]: 1.13‐5.09), but this combination was not associated with carotid plaques (OR: 2.62, 95% CI: 0.93‐7.38). The results suggested that the combination of hs‐CRP and Lp‐PLA2 were better predictors than either protein alone with regard to carotid atherosclerosis.

Given the high level of exposure to SARS-CoV-2, cold-chain workers are considered priority vaccination groups. To date, many studies have reported on the willingness within distinct populations to be vaccinated against COVID-19, whereas it has not been reported among cold-chain workers worldwide. To address this void, we conducted a cross-sectional survey to gather general information, COVID-19-related knowledge, attitudes, and practices (KAP), and willingness to receive a COVID-19 vaccine among cold-chain workers in Shenzhen, China. Binary logistic analyses were conducted to explore the associations between COVID-19-related KAP factors and the willingness for COVID-19 vaccination. Among 244 cold-chain workers, 76% indicated that they were willing to be vaccinated. Knowledge about SARS-CoV-2, comprehending the most effective prevention, understanding the transmission routes, and recognizing the priority vaccination groups were positively associated with willingness to be vaccinated against COVID-19. Regarding attitude factors, perceiving the social harmfulness and severity of COVID-19 were related to a higher willingness to vaccination. Participants considering themselves a priority group for COVID-19 vaccination were more likely to get vaccinated. For practice factors, attaining more knowledge and higher self-reported compliance with maintaining adequate ventilation were also positively associated with the dependent variable. Agreement on the importance of COVID-19 vaccination was the most frequent reason for accepting the COVID-19 vaccine; additionally, concerns about side effects and insufficient understanding of efficacy were the main factors contributing to vaccine refusal. Enhancing KAP levels related to COVID-19 helps promote vaccine acceptance. Health authorities should promptly implement educational activities following the updated vaccine status among cold-chain workers.