Conflict of interest statement
The authors declare that there is no conflict of interest.
Funding
The study received no extramural funding.
Authors’ contributions
Hop Vu Dinh, Huong Nguyen Thi Lien, Hanh Nguyen Van, and Hoang Le conceived, designed, interpreted the data, and coordinated the work. Hop Vu Dinh wrote the manuscript. Cuong An Manh and Anh Phi Thi Tu collected, double checked the data, and participated in interpreting the data. Huong Nguyen Thi Lien, Hanh Nguyen Van, and Hoang Le reviewed the manuscript. All authors jointly contributed to the final version of the manuscript.
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