About the Authors

William Chi Wai Wong

‡ These authors contributed equally to this work and are co-first authors.

Affiliation Department of Family Medicine and Primary Care, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong S.A.R., China

Yanping Zhao

zhaohelen@hku.hk

‡ These authors contributed equally to this work and are co-first authors.

Affiliation Department of Family Medicine and Primary Care, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong S.A.R., China

Ngai Sze Wong

Affiliations University of North Carolina Project-China, Guangzhou, Guangdong Province, China, Institute for Global Health & Infectious Diseases, University of North Carolina at Chapel Hill, Chapel Hill, United States of America

William L. Parish

Affiliation Sociology Department, University of Chicago, Chicago, Illinois, United States of America

Heidi Yin Hai Miu

Affiliation Department of Family Medicine and Primary Care, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong S.A.R., China

Li-Gang Yang

Affiliation Guangdong Provincial Centers for Skin Diseases and STI Control, Guangzhou, Guangdong Province, China

Michael Emch

Affiliation Department of Geography, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina, United States of America

King Man Ho

Affiliation Social Hygiene Service, Department of Health, Hong Kong Government, Hong Kong S.A.R., China

Francois Yeung Fong

Affiliation Hong Kong Sexual Health Centre, Hong Kong S.A.R., China

Joseph D. Tucker

Affiliations University of North Carolina Project-China, Guangzhou, Guangdong Province, China, London School of Hygiene and Tropical Medicine, London, United Kingdom

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceptualization: WCWW. Data curation: YZ HYHM WLP. Formal analysis: YZ WLP NSW. Funding acquisition: WCWW JT ME KMH LGY YZ. Investigation: YZ HYHM. Methodology: WCWW YZ JT. Project administration: YZ HYHM. Supervision: WCWW. Validation: YZ HYHM WCWW. Visualization: NSW. Writing – original draft: YZ. Writing – review & editing: YZ WCWW WLP HYHM NSW JT LGY ME KMH FYF.