- Correspondence to Professor Ping Zhong, Department of AIDS and STD, Shanghai Municipal Center for Disease Control and Prevention, Shanghai Municipal Institutes for Preventive Medicine, 1380 Zhongshan Road (W), Shanghai 200336, China; and Pingmin Wei, Teaching and Research Office of Epidemiology and Health Statistics, School of Public Health, Southeast University, 87 Dingjiaqiao Road (W), Nanjing 210009, China;
- Received 26 December 2016
- Revised 10 May 2017
- Accepted 10 June 2017
- Published online 7 August 2017.
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