Trail To Evaluate the Immunity Duration of Different Sequential Immunization Schedules and Effectiveness for Bivalent Oral Poliomyelitis Vaccine Co-administered With IPV Booster Immunization for Poliovirus Vaccine

According to the requirement of the Strategy of Polio Eradication & Endgame Strategic Plan 2013-2018, bivalent oral attenuated live poliomyelitis vaccine against type 1 and 3 (bOPV) and inactivated poliomyelitis vaccine made by Sabin strain (sIPV) need to be used to eradiation both the wild poliovirus and vaccine-derived poliovirus. To evaluate the safety and immunogenicity by different sequential immunization 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 Guangxi Province in China. A total of 1200 infants at 2 months old were selected, and randomlydivided into 12 different groups (100 individuals were included in each group) administrated the vaccines at 0, 28, 56 days schedule.The detail of each group as following:1)1-dose cIPV + 2-dose bOPV (Candy); 2)1-dose sIPV + 2-dose bOPV (Candy); 3)2-dose cIPV + 1-dose bOPV (Candy); 4)2-dose sIPV + 1-dose bOPV (Candy); 5)2-dose cIPV + 1-dose tOPV (Candy); 6)2-dose sIPV + 1-dose tOPV (Candy); 7)1-dose cIPV + 2-dose bOPV (Liquid); 8)1-dose sIPV + 2-dose bOPV (Liquid); 9)2-dose cIPV + 1-dose bOPV (Liquid); 10)2-dose sIPV + 1-dose bOPV (Liquid); 11)2-dose cIPV + 1-dose tOPV (Liquid); 12)2-dose sIPV + 1-dose tOPV (Liquid).Blood Sample was collected before vaccination and one month after the third dose of vaccination. Neutralization antibody against type I, Type I and Type III poliomyelitis virus were detected to evaluate the seroprotection rates and antibody geometric mean concentrations. The fecal samples were collected to test viral shedding.The safety by different sequential schedule of the vaccines was also evaluated.This part of study have already been done in 2016.

To further evaluate the immunity duration of different sequential immunization schedules for bOPV and IPV ,more importantly,trying to research the effectiveness of bOPV booster immunization,the previous study will continue.

The detail of the research as following:

The subject, who have already receipted 3-dose polio vaccine for primary immunization in phase III clinical trail in Guangxi and with the result of the paired-serum, are recruited again.In order to research the immunity durability of primary immunizations of primary immunization(3 doses of immunization),blood samples are collected from the subject aged 24 months,36 months and 48 months separately.Neutralization antibody titers for against type I, Type I and Type III poliomyelitis virus are detected,moreover,the positive rate and antibody geometric mean titers are analyzed.

A single dose of bOPV（liquid/candy) will be given orally to subjects at the age of 48 months which can in support of the effectiveness research of booster immunization with bOPV. To protect the rights and interests of subjects,the investigator can use other poliovirus vaccine such as IPV instead when bOPV（liquid/candy）is not available.