This study is a supplementary study of an already finished randomised, double-blinded, and placebo controlled phase 2 clinical trial of an Sabin strain inactivated poliovirus vaccine (sIPV) manufactured by Sinovac Biotech Ltd., Beijing China. The purpose of this study is to evaluate the cross-neutralization capacity of the serum immuned by the investigational sIPV against 10 individual virus strains.
This study is a open-labelled study conducted based on an already finished phase 2 study of the investigational sIPV in 600 healthy infants aged 2-months old. The purpose of this study is to evaluate the cross-neutralization capacity of the serum immuned by the investigational sIPV against 10 individual virus strains. Paired pre-immune and post-immune serum from 250 participants of the phase 2 trial, with 50 in each group including the low-, medium- and high- dosage group, control wild poliovirus vaccine (wIPV) group and control sIPV group, was selected and sent to China Center for Disease Control and Prevention (CDC) for the cross-neutralization assay to determine the neutralizing antibody titer against 10 individual virus strains including Sabin strains (type 1, 2, and 3), Salk strains (Mahoney, MEF-1, and Saukett), cVDPV (type 1, 2, and 3) and Xinjiang wild strain of type 1(Xinjiang wIPV1). All the subjects in this study had been vaccinated at the schedule of month 0,1, and 2 in the phase 2 clinical trial.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
NONE
Enrollment
250
Antigen content: 7.5, 22.5, and 22.5 D-antigen unite for type 1, 2, and 3 in 0.5 ml diluent per dose
Antigen content: 15, 45, and 45 D-antigen unite for type 1, 2, and 3 in 0.5 ml diluent per dose
Pizhou Center for Disease Control and Prevention
Pizhou, Jiangsu, China
Immunity index of seroconversion rate
The seroconversion rates of neutralizing antibody against 10 individual virus strains (Sabin 1, Sabin2, Sabin 3, Mahoney 1, MEF-1, Saukett, cVDPV1, cVDPV2, cVDPV3, and Xinjiang wIPV1)
Time frame: One month after three doses of vaccination
Immunity index of geometric mean titer (GMT)
The GMT of neutralizing antibody against 10 individual virus strains (Sabin 1, Sabin2, Sabin 3, Mahoney 1, MEF-1, Saukett, cVDPV1, cVDPV2, cVDPV3, and Xinjiang wIPV1)
Time frame: One month after three doses of vaccination
Immunity index of geometric mean ratio (GMR)
The GMR of neutralizing antibody against 10 individual virus strains (Sabin 1, Sabin2, Sabin 3, Mahoney 1, MEF-1, Saukett, cVDPV1, cVDPV2, cVDPV3, and Xinjiang wIPV1)
Time frame: One month after three doses of vaccination
Immunity index of seropositivity rate
The seropositivity rate of neutralizing antibody against 10 individual virus strains (Sabin 1, Sabin2, Sabin 3, Mahoney 1, MEF-1, Saukett, cVDPV1, cVDPV2, cVDPV3, and Xinjiang wIPV1)
Time frame: One month after three doses of vaccination
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Antigen content: 22.5, 67.5, and 67.5 D-antigen unite for type 1, 2, and 3 in 0.5 ml diluent per dose
Antigen content: 40, 8, and 32 D-antigen unite for type 1, 2, and 3 in 0.5 ml diluent per dose
Antigen content: 30, 32, and 45 D-antigen unite for type 1, 2, and 3 in 0.5 ml diluent per dose