Poliomyelitis (Live) Vaccine Type I Type III (Human Diploid Cell), Oral( Institute of Medical Biology Chinese Academy of Medical Sciences)

Trail To Evaluate the Immunity Duration of healthy children who already took part in " The safety and immunogenicity by different sequential schedules of bOPV and bOPV in dragee candy with sIPV, a randomized, double blind, single center and parallel phase Ⅲ clinic trial was performed in Infants of two-month old in Guangxi Province, China" and continue to search for the effects of booster immunization.