In the article, the authors have missed to include “Funding” section, on p. 589, before “Conflicts of interest” statement. Funding statement is provided below:
FundingThis work was supported by grants from: (1) the Excellent Academic Leaders of Shanghai Public Health Field (No. GWDTR201225); and (2) the Shanghai Municipal Health & Family Planning Commission (No. 20114067).
The authors would like to apologise for any inconvenience caused.