Vietnam, which is testing a dengue fever vaccine produced by Swiss company Sanofi, is expected to approve it soon since it has successfully undergone the second phase of testing on humans.
Dr. Tran Ngoc Huu, director of the Ho Chi Minh based Pasteur Institute, said the third phase of testing involved Long Xuyen and My Tho cities.
These two Mekong Delta cities were selected because they had reported a largest number of dengue fever infections last year, he said.
Twelve other Asian countries have independently engaged in testing the vaccine, with Thailand expected to announce the preliminary results by 2012.
By the end of September Vietnam had 45,142 cases of infections with 39 deaths confirmed.