Application of artificial intelligence to the public health education.

With the global outbreak of coronavirus disease 2019 (COVID-19), public health has received unprecedented attention. The cultivation of emergency and compound professionals is the general trend through public health education. However, current public health education is limited to traditional teaching models that struggle to balance theory and practice. Fortunately, the development of artificial intelligence (AI) has entered the stage of intelligent cognition. The introduction of AI in education has opened a new era of computer-assisted education, which brought new possibilities for teaching and learning in public health education. AI-based on big data not only provides abundant resources for public health research and management but also brings convenience for students to obtain public health data and information, which is conducive to the construction of introductory professional courses for students. In this review, we elaborated on the current status and limitations of public health education, summarized the application of AI in public health practice, and further proposed a framework for how to integrate AI into public health education curriculum. With the rapid technological advancements, we believe that AI will revolutionize the education paradigm of public health and help respond to public health emergencies.

Application of artificial intelligence to the public health education

With the global outbreak of coronavirus disease 2019 (COVID-19), public health has received unprecedented attention. The cultivation of emergency and compound professionals is the general trend through public health education. However, current public health education is limited to traditional teaching models that struggle to balance theory and practice. Fortunately, the development of artificial intelligence (AI) has entered the stage of intelligent cognition. The introduction of AI in education has opened a new era of computer-assisted education, which brought new possibilities for teaching and learning in public health education. AI-based on big data not only provides abundant resources for public health research and management but also brings convenience for students to obtain public health data and information, which is conducive to the construction of introductory professional courses for students. In this review, we elaborated on the current status and limitations of public health education, summarized the application of AI in public health practice, and further proposed a framework for how to integrate AI into public health education curriculum. With the rapid technological advancements, we believe that AI will revolutionize the education paradigm of public health and help respond to public health emergencies.

Bibliometric analysis of traditional Chinese medicine for smoking cessation.

INTRODUCTION: Smoking cessation is an efficient approach to reducing disease burden. Traditional Chinese Medicine (TCM) therapies such as acupuncture, acupressure, and herbal drugs are often used to help quit smoking. However, there is a lack of overarching bibliometric analysis of the clinical research on smoking cessation focusing on TCM. The aim of our study is to explore the current patterns and trends of TCM therapy for smoking cessation through bibliometric methods with visual presentation. METHODS: This study is an assessment of academic publications retrieved from the Scopus database on smoking cessation using TCM therapy published in the period 2005-2021. Sankey diagram, word-cloud, network analysis, thematic maps, tree-maps, and the collaborative work of authors, institutions and countries, were used to identify research trends on TCM therapy for smoking cessation. The total cited index and H-index (for journals, authors, countries, organizations) were used to identify the trends of worldwide development by R Package and Excel 2016. RESULTS: There was an upward trend, with some fluctuations, of 1908 articles from 2005 to 2021. The most productive country was China. The top institution in this field was Beijing University. The dominant author that contributed to TCM therapy for smoking cessation was Wang Y, who has the highest H-Index. The most productive cited journals were Evidence-Based Complementary and Alternative Medicines and the Chinese Journal of Clinical Rehabilitation. Liu L, (2011, STROKE) had the highest centrality. The keywords 'acupuncture', 'traditional Chinese medicine', 'colitis', 'hypertension', 'chronic obstructive pulmonary disease', 'risk factors' and 'alternative medicine' ranked highest in frequency. The diseases of healthy people concerned mainly cardiovascular, cancer, diabetes, hypertension and pregnancy. The diseases of the patients concerned mainly cancer, diabetes, hematopathy, stroke, cardiovascular, diabetes, lung disease, and hypertension. Treatment methods were mainly traditional Chinese medicine and acupuncture. The research methods mainly included randomized controlled trials that were multi-center and double-blind. CONCLUSIONS: A substantial number of articles on TCM therapy for smoking cessation, mainly focusing on TCM and acupuncture were identified. It is worth noting that research that focused on TCM therapy for smoking cessation also was related to COVID-19.

Neutralization of five SARS-CoV-2 variants of concern by convalescent and BBIBP-CorV vaccinee serum.

The prevalence of SARS-CoV-2 variants of concern (VOCs) is still escalating throughout the world. However, the level of neutralization of the inactivated viral vaccine recipients' sera and convalescent sera against all VOCs, including B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma), B.1.617.2 (Delta), and B.1.1.529 (Omicron) remains to be lack of comparative analysis. Therefore, we constructed pseudoviruses of five VOCs using a lentiviral-based system and analyzed their viral infectivity and neutralization resistance to convalescent and BBIBP-CorV vaccinee serum at different times. Our results show that, compared with the wild-type strain (WT), five VOC pseudoviruses showed higher infection, of which B.1.617.2 and B.1.1.529 variant pseudoviruses exhibited higher infection rates than wild-type or other VOC strains, respectively. Sera from 10 vaccinated individuals at the 1, 3 and 5-month post second dose or from 10 convalescent at 14 and 200 days after discharge retained neutralizing activity against all strains but exhibited decreased neutralization activity significantly against the five VOC variant pseudoviruses over time compared to WT. Notably, 100% (30/30) of the vaccinee serum samples showed more than a 2.5-fold reduction in neutralizing activity against B.1.1.529, and 90% (18/20) of the convalescent serum samples showed more than 2.5-fold reduction in neutralization against B.1.1.529. These findings demonstrate the reduced protection against the VOCs in vaccinated and convalescent individuals over time, indicating that it is necessary to have a booster shot and develop new vaccines capable of eliciting broad neutralization antibodies.

The neutralization of B.1.617.1 and B.1.1.529 sera from convalescent patients and BBIBP-CorV vaccines.

The SARS-CoV-2 variants B.1.617.1 (Kappa) contain multiple mutations in the spike protein. However, the effect of B.1.617.1 lineage-related mutants on viral infectivity and inactivated-virus vaccine efficacy remains to be defined. We therefore constructed 12 B.1.617.1-related pseudoviruses and systematically studied the effects of mutations on virus infectivity and neutralization resistance to convalescent and inactivated virus vaccine sera. Our results show that the B.1.617.1 variant exhibited both higher infectivity and neutralization resistance in sera at 1 or 3 months after vaccination of 28 individuals and at 14 and 200 days after discharge of 15 convalescents. Notably, 89% of vaccines and 100% of the convalescent serum samples showed more than 2.5-fold reduction in neutralization against one single mutation: E484Q. Besides, we found a significant decrease in neutralizing activity in convalescent patients and BBIBP-CorV vaccines for B.1.1.529. These findings demonstrate that inactivated-virus vaccination or convalescent sera showed reduced, but still significant, neutralization against the B.1.617.1 variant.

The SARS-CoV-2 receptor ACE2 is expressed in mouse pericytes but not endothelial cells: Implications for COVID-19 vascular research.

Humanized mouse models and mouse-adapted SARS-CoV-2 virus are increasingly used to study COVID-19 pathogenesis, so it is important to learn where the SARS-CoV-2 receptor ACE2 is expressed. Here we mapped ACE2 expression during mouse postnatal development and in adulthood. Pericytes in the CNS, heart, and pancreas express ACE2 strongly, as do perineurial and adrenal fibroblasts, whereas endothelial cells do not at any location analyzed. In a number of other organs, pericytes do not express ACE2, including in the lung where ACE2 instead is expressed in bronchial epithelium and alveolar type II cells. The onset of ACE2 expression is organ specific: in bronchial epithelium already at birth, in brain pericytes before, and in heart pericytes after postnatal day 10.5. Establishing the vascular localization of ACE2 expression is central to correctly interpret data from modeling COVID-19 in the mouse and may shed light on the cause of vascular COVID-19 complications.

State-of-the-art evidence of traditional Chinese medicine for treating coronavirus disease 2019

Traditional Chinese medicine has widely been used internationally in the treatment of coronavirus disease 2019 (COVID-19) since January 2020. There has been great interest in initiating clinical studies testing different Chinese medicine therapies for COVID-19, but the majority of registered studies have yet to move forward due to a lack of COVID-19 patients in mainland China. The aim of this article was to systematically review the current clinical research evidence on Chinese medicine for treating COVID-19 from international and domestic bibliographic databases to reflect on the advances in this field.

Traditional Chinese medicine for COVID-19 pandemic and emerging challenges: An online cross-sectional survey in China.

BACKGROUND: We aimed to investigate use of infection control behaviours, preventative and therapeutic interventions, and outcomes among respondents to an online survey during the COVID-19 pandemic in China. METHODS: The survey was designed by an international team, translated and adapted to simplified Chinese, including 132 kinds of traditional Chinese medicine (TCM) preparation recommended by guidelines. It was distributed and collected from February to May 2021, with data analysed by WPS spreadsheet and wjx.cn. Descriptive statistics were used to describe demographics and clinical characteristics, diagnosis, treatments, preventative behaviours and interventions, and their associated outcomes. RESULTS: The survey was accessed 503 times with 341 (67.8%) completions covering 23 provinces and four municipalities in China. Most (282/341, 82.7%) respondents reported no symptoms during the pandemic and the majority (290/341, 85.0%) reported having a SARS-CoV-2 PCR test at some point. Forty-five (13.2%) reported having a respiratory infection, among which 19 (42.2%) took one or more categories of modern medicine, e.g. painkillers, antibiotics; 16 (35.6%) used TCM interventions(s); while seven respondents combined TCM with modern medicine. All respondents reported using at least one behavioural or medical approach to prevention, with 22.3% taking TCM and 5.3% taking modern medicines. No respondents reported having a critical condition related to COVID-19. CONCLUSION: We found evidence of widespread use of infection control behaviours, modern medicines and TCM for treatment and prevention of COVID-19 and other respiratory symptoms. Larger scale studies are warranted, including a more representative sample exploring TCM preparations recommended in clinical guidelines.

Integrating Chinese and western medicine for COVID-19: A living evidence-based guideline (version 1).

BACKGROUND: The coronavirus disease 2019 (COVID-19) has turned into a pandemic and resulted in huge death tolls and burdens. Integrating Chinese and western medicine has played an important role in the fight against the COVID-19 pandemic. PURPOSE: We aimed to develop a living evidence-based guideline of integrating Chinese and western medicine for COVID-19. STUDY DESIGN: Living evidence-based guideline. METHODS: This living guideline was developed using internationally recognized and accepted guideline standards, dynamically monitoring the release of new clinical evidence, and quickly updating the linked living systematic review, evidence summary tables, and recommendations. Modified Delphi method was used to reach consensus for all recommendations. The certainty of the evidence, resources, and other factors were fully considered, and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used to rate the certainty of evidence and the strength of recommendations. RESULTS: The first version of this living guidance focuses on patients who are mild or moderate COVID-19. A multidisciplinary guideline development panel was established. Ten clinical questions were identified based on the status of evidence and a face-to-face experts' consensus. Finally, nine recommendations were reached consensus, and were formulated from systematic reviews of the benefits and harms, certainty of evidence, public accessibility, policy supports, feedback on proposed recommendations from multidisciplinary experts, and consensus meetings. CONCLUSION: This guideline panel made nine recommendations, which covered five traditional Chinese medicine (TCM) prescription granules/decoction (MXXFJD, QFPD, XFBD, TJQW, and JWDY), three Chinese patent medicines (LHQW granules/capsule, JHQG granules, and LHQK granules), and one Chinese herbal injection (XBJ injection). Of them, two were strongly recommended (LHQW granules/capsule and QFPD decoction), and five were weakly recommended (MXXFJD decoction, XFBD decoction, JHQG granules, TJQW granules, and JWDY decoction) for the treatment of mild and moderate COVID-19; two were weakly recommended against (XBJ injection and LHQK granules) the treatment of mild and moderate COVID-19. The users of this living guideline are most likely to be clinicians, patients, governments, ministries, and health administrators.

Chinese medicine participates in clinical research on the treatment of new coronavirus pneumonia: strategy and method thinking

This article discusses the interplay of TCM and medical treatment for COVID-19. The generalisation of the treatment of pneumonia caused by the type of coronavirus. Temporarily Yuan is referred to as Ye Xingyi, Yuanyao, Ye Xingyi requires the establishment of a combination of Chinese and Western medicine.

Methodological key points and reporting suggestions for retrospective case series study on using traditional Chinese medicine for treatment of COVID-19

Recently a series of case-analysis articles have been published in Chinese Journals for traditional Chinese medicine treatment of coronavirus disease-2019 (COVID-19). Most of them were retrospective case series study. Considering the characteristics and methodological limitations of such kinds of research, authors aimed to introduce reasonable methodological key points and reporting suggestions for uncontrolled retrospective case series study from the perspective of clinical research, thus to ensure credibility and avoid bias of the results.

Immediate Psychosocial Impact on Healthcare Workers During COVID-19 Pandemic in China: A Systematic Review and Meta-Analysis.

Objectives: The corona virus disease-2019 (COVID-19) pandemic spread globally, and we aimed to investigate the psychosocial impact on healthcare workers (HWs) in China during the pandemic. Methods: In this systematic review and meta-analysis, we searched seven electronic databases for cross-sectional studies on psychosocial impact on HWs in relation to COVID-19 from January 1, 2020 to October 7, 2020. We included primary studies involving Chinese HWs during the pandemic, and data were extracted from the published articles. Our primary outcome was prevalence of anxiety, depression, and stress disorders. We pooled prevalence value with their 95% confidence interval using random effect models and assessed study quality on the basis of an 11-item checklist recommended by the Agency for Healthcare Research and Quality. The study protocol was registered in PROSPERO (CRD42020195843). Results: We identified 25 articles comprising a total of 30,841 completed questionnaires and 22 studies for meta-analysis. The prevalence of anxiety, depression, and stress disorders was 34.4% (29.5-39.4%), 31.1% (24.5-37.7%), and 29.1% (24.3-33.8%) for HWs. The pooled prevalence of anxiety disorders for HWs from late January to early February was 46.4% (42.9-49.9%), significantly higher than those in mid-term February (28.0%, 23.9-32.1%) and after late February (27.6%, 16.0-39.2%). The pooled prevalence of depression disorders for HWs from late January to early February was 46.5% (38.8-54.2%), significantly higher than those in mid-term February (27.1%, 19.8-34.5%) and after late February (32.9%, 16.2-49.5%). HWs working in Hubei Province had a higher prevalence of anxiety (37.9 vs. 30.8%) and a lower prevalence of depression (27.5 vs. 34.7%) than those working in other regions. Nurses had a higher prevalence of anxiety (44.1 vs. 29.0%) and depression (34.1 vs. 29.2%) than other HWs. Conclusions: About one-third of HWs in China suffered anxiety, depression, and stress at the early epidemic of COVID-19. HWs in Hubei Province, especially nurses, had a higher prevalence of psychological disorders. During the pandemic, a negative psychological state may persist in a proportion of Chinese HWs, fluctuating with the control of the pandemic. The long-term impact should continue to be observed. Attention should be paid to HWs for their psychological impact due to the pandemic. Systematic Review Registration: The study protocol was registered with PROSPERO (CRD42020195843).

Therapeutic effects and safety of oral Chinese patent medicine for COVID-19: A rapid systematic review and meta-analysis of randomized controlled trials.

INTRODUCTION: Chinese patent medicine (CPM) is an indispensable part of traditional Chinese medicine. Coronavirus Disease 2019 (COVID-19) manifests is an acute respiratory infectious disease. This systematic review aimed to evaluate the therapeutic effects and safety of oral CPM for COVID-19. METHODS: We included randomized controlled trials (RCTs) that tested oral CPM for the treatment of COVID-19 identified from publications in CNKI, Wanfang, VIP, Web of Science, SinoMed, PubMed, Embase, BioRxiv, MedRxiv and arXiv before November 2nd, 2020. The risk of bias for each trial was assessed using the Cochrane Risk of Bias Tool 2.0. RevMan 5.4 software was used for data analyses. The certainty of the evidence was assessed using the online GRADEpro tool. RESULTS: Seven RCTs including 1079 participants were identified. The overall bias was assessed as "-high risk of bias" for all included trials. Oral CPM investigated were: Lianhua Qingwen capsule/granules (LHQW), Jinhua Qinggan granules (JHQG), Huoxiang Zhengqi dripping pills (HXZQ), Toujie Quwen granules (TJQW) and Lianhua Qingke granules (LHQK). Compared with conventional western therapy alone for people with COVID-19: regarding the main outcomes, the results showed that oral CPM combined with conventional western therapy improved cure rate (RR = 1.20, 95 % CI 1.04-1.38, involving LHQW and TJQW), reduced aggravation rate (RR = 0.50, 95 % CI 0.29 - 0.85, involving LHQW, JHQG, LHQK and TJQW); with regard to additional outcomes, the results showed that add-on oral CPM shortened the duration of fever, cough and fatigue, improved the recovery rate of cough and fatigue, and increased the improvement and recovery rate of chest CT manifestations. There were some differences in therapeutic effects among various CPMs for the same COVID-19 outcome. The use of TJQW and LHQG appeared not to increase the risk of adverse events, but JHQG may cause mild diarrhea. CONCLUSION: Low-certainty or very low-certainty evidence demonstrated that oral CPM may have add-on potential therapeutic effects for patients with non-serious COVID-19. These findings need to be further confirmed by well-designed clinical trials with adequate sample sizes.

A living systematic review of the psychological problems in people suffering from COVID-19.

OBJECTIVES: We aimed to investigate the psychological problems on people infected with SARS-CoV-2 during the pandemic. METHODS: In this living systematic review and meta-analyses, we searched seven electronic databases for cross-sectional studies and longitudinal studies on psychological problems on COVID-19 patients from Jan 1, 2020 to Oct 7, 2020. The primary outcome was prevalence of various psychological problems such as anxiety, depression, stress, insomnia, somatization, and fear. We pooled data for prevalence with their 95% confidence interval (CI) using random effect models and assessed the study quality based on the 11-item checklist recommended by the Agency for Healthcare Research and Quality. RESULTS: Fourty-four studies, including studies from China(35), Italy(2), Iran(2), India(1), Korea(1), Ecuador(1), Switzerland(1), Germany(1), were identified by comprising a total of 8587 completed questionnaires and 38 studies for meta-analyses. The prevalence of anxiety, depression, post-traumatic stress disorder(PTSD), insomnia, somatization, and fear in patients with COVID-19 was 16.6% (10.1%-23.1%), 37.7% (29.3%-46.2%), 41.5% (9.3%-73.7%), 68.3% (48.6%-88.0%), 36.5% (20.2%-52.8%), 47.6% (9.4%-85.7%), respectively. The prevalence of anxiety, depression, and insomnia in severe COVID-19 patients (intensive care unit inpatients) was higher than mild or clinically stable COVID-19 patients. LIMITATIONS: A significant degree of heterogeneity in terms of populations, sampling methods, scales was noted across studies. CONCLUSIONS: There existed high proportions of COVID-19 patients with psychological problem. The prevalence of psychological problems was closely related to the patients themselves, their surroundings and social support. It is imperative to provide ontime psychological care service for COVID-19 patients and to follow-up them for a longer period.

Development of potent and selective inhibitors targeting the papain-like protease of SARS-CoV-2.

The COVID-19 pandemic has been disastrous to society and effective drugs are urgently needed. The papain-like protease domain (PLpro) of SARS-CoV-2 (SCoV2) is indispensable for viral replication and represents a putative target for pharmacological intervention. In this work, we describe the development of a potent and selective SCoV2 PLpro inhibitor, 19. The inhibitor not only effectively blocks substrate cleavage and immunosuppressive function imparted by PLpro, but also markedly mitigates SCoV2 replication in human cells, with a submicromolar IC50. We further present a convenient and sensitive activity probe, 7, and complementary assays to readily evaluate SCoV2 PLpro inhibitors in vitro or in cells. In addition, we disclose the co-crystal structure of SCoV2 PLpro in complex with a prototype inhibitor, which illuminates their detailed binding mode. Overall, these findings provide promising leads and important tools for drug discovery aiming to target SCoV2 PLpro.

Chinese Herbal Medicine Used With or Without Conventional Western Therapy for COVID-19: An Evidence Review of Clinical Studies.

Objective: To present the evidence of the therapeutic effects and safety of Chinese herbal medicine (CHM) used with or without conventional western therapy for COVID-19. Methods: Clinical studies on the therapeutic effects and safety of CHM for COVID-19 were included. We summarized the general characteristics of included studies, evaluated methodological quality of randomized controlled trials (RCTs) using the Cochrane risk of bias tool, analyzed the use of CHM, used Revman 5.4 software to present the risk ratio (RR) or mean difference (MD) and their 95% confidence interval (CI) to estimate the therapeutic effects and safety of CHM. Results: A total of 58 clinical studies were identified including RCTs (17.24%, 10), non-randomized controlled trials (1.72%, 1), retrospective studies with a control group (18.97%, 11), case-series (20.69%, 12) and case-reports (41.38%, 24). No RCTs of high methodological quality were identified. The most frequently tested oral Chinese patent medicine, Chinese herbal medicine injection or prescribed herbal decoction were: Lianhua Qingwen granule/capsule, Xuebijing injection and Maxing Shigan Tang. In terms of aggravation rate, pooled analyses showed that there were statistical differences between the intervention group and the comparator group (RR 0.42, 95% CI 0.21 to 0.82, six RCTs; RR 0.38, 95% CI 0.23 to 0.64, five retrospective studies with a control group), that is, CHM plus conventional western therapy appeared better than conventional western therapy alone in reducing aggravation rate. In addition, compared with conventional western therapy, CHM plus conventional western therapy had potential advantages in increasing the recovery rate and shortening the duration of fever, cough and fatigue, improving the negative conversion rate of nucleic acid test, and increasing the improvement rate of chest CT manifestations and shortening the time from receiving the treatment to the beginning of chest CT manifestations improvement. For adverse events, pooled data showed that there were no statistical differences between the CHM and the control groups. Conclusion: Current low certainty evidence suggests that there maybe a tendency that CHM plus conventional western therapy is superior to conventional western therapy alone. The use of CHM did not increase the risk of adverse events.

Face masks matter: Eurasian tree sparrows show reduced fear responses to people wearing face masks during the COVID-19 pandemic.

Continuous exposure to human activity has led to considerable behavioural changes in some wildlife populations. Animals are more likely to survive in a changing environment by adjusting their behaviour to repeatedly occurring but harmless stimulations. During the COVID-19 pandemic, starting in late 2019, face masks were recommended to the public to prevent the spread of pathogens. In this context, we compared the flight initiation distance (FID) of the Eurasian tree sparrow (Passer montanus), a commonly seen bird across China, in Yibin and Dazhou, Sichuan, in response to people with or without face masks. After continuous exposure to people wearing face masks for nearly six months, sparrows evidently became adapted to people wearing face masks, and correspondingly showed shorter FIDs in response to people wearing masks. To our knowledge, this is the first study showing that birds show reduced fear responses to people wearing face masks during the COVID-19 pandemic. Our results suggest a novel aspect of short-term adaptation of wildlife to human behaviour, and that the learning ability of sparrows allows them to adjust their behaviours to adapt to such subtle changes in the environment.

Characteristics of registered clinical trials on traditional Chinese medicine for coronavirus disease 2019 (COVID-19): A scoping review.

INTRODUCTION: Traditional Chinese medicine (TCM) has been fully committed to the treatment of coronavirus disease 2019 (COVID-19) in China. An increasing number of clinical trials have been registered to evaluate the effects of TCM for COVID-19. The aim of this study was to review the existing TCM clinical trial registrations and identify potentially promising and available TCM therapies, in order to provide a reference for the global management of COVID-19. METHODS: All clinical trials on TCM for COVID-19 registered in registry platforms worldwide were searched. The data of registration temporal trend, design, objective, interventions, and relevant information were reviewed and summarized. RESULTS: 161 TCM trials were identified from three registries (January 26 to May 14 2020,). Of these, 94 (58.4%) were randomized controlled trials and 114 trials (70.8%) assessed therapeutic effects; while the remainder focused on prevention, rehabilitation, and the epidemiology of TCM syndromes. Eight trials (5.0%) had completed their recruitment. TCM interventions with potential for further evaluation in terms of prevention were moxibustion, Huoxiang Zhengqi pill and Jinye Baidu granules. For treatment of COVID-19, Qingfei Paidu decoction, Huashi Baidu decoction, Lianhua Qingwen capsules, Toujie Quwen granules and Xiyanping injection, and Xuebijing injection were to be tested for their therapeutic effects and symptoms relief. For rehabilitation, Tai Chi and Liuzijue were to be tested for improving patients' lung function. CONCLUSION: Some potentially promising TCM interventions have been identified and deserve further evaluation to establish their evidence base, particularly on populations outside of China.

Contact Settings and Risk for Transmission in 3410 Close Contacts of Patients With COVID-19 in Guangzhou, China : A Prospective Cohort Study.

BACKGROUND: Risk for transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to close contacts of infected persons has not been well estimated. OBJECTIVE: To evaluate the risk for transmission of SARS-CoV-2 to close contacts in different settings. DESIGN: Prospective cohort study. SETTING: Close contacts of persons infected with SARS-CoV-2 in Guangzhou, China. PARTICIPANTS: 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. RESULTS: 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 health care 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]). LIMITATION: 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. CONCLUSION: 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. PRIMARY FUNDING SOURCE: Guangdong Province Higher Vocational Colleges and Schools Pearl River Scholar Funded Scheme.