About the Authors

Zhifang Wang

Affiliation Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, Zhejiang Province, P. R. China

Rui Yan

Affiliation Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, Zhejiang Province, P. R. China

Hanqing He

Affiliation Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, Zhejiang Province, P. R. China

Qian Li

Affiliation Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, Zhejiang Province, P. R. China

Guohua Chen

Affiliation Cixi City Center for Disease Control and Prevention, Cixi, Ningbo, P. R. China

Shengxu Yang

Affiliation Sanmen County Center for Disease Control and Prevention, Sanmen, Taizhou, P. R. China

Enfu Chen

enfchen@cdc.zj.cn

Affiliation Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, Zhejiang Province, P. R. China

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: EC. Performed the experiments: HH QL GC SY. Analyzed the data: ZW RY. Contributed reagents/materials/analysis tools: EC. Wrote the paper: ZW.