Abstract
Background: The Sabin-strain-based inactivated poliovirus vaccine (sIPV) plays an important role in poliomyelitis eradication in developing countries. As part of the phase III clinical development program, this study aimed to evaluate the safety, immunogenicity and lot-to-lot consistency of the sIPV in 2-month-old infants. Method: We conducted a phase III, randomized, double-blind, positive-controlled trial in which 1300 healthy infants were randomly assigned to four groups in a 1:1:1:1 ratio to receive one of the three lots of the sIPV or the control IPV at 2, 3 and 4 months of age. Serum samples were collected before the first dose and 30 days after the third dose of vaccination to assess the immunogenicity. Solicited local and systemic reactions were recorded within 7 days and unsolicited adverse events within 30 days after each vaccination. Results: Of the 1300 randomized infants, 1190 infants completed the study and were included in the per-protocol population. The seroconversion rates in the three lots of the sIPV were 95.67%, 97.03% and 95.59%, respectively, for type 1; 94.33%, 93.73% and 92.88%, respectively, for type 2; and 98.67%, 99.67% and 99.32%, respectively, for type 3. The ratios of GMTs for poliovirus types 1, 2 and 3 of each pair of lots were all between 0.67 and 1.50, therefore meeting the predefined immunological equivalence criteria. For the seroconversion rate of poliovirus types 1, 2 and 3, the pooled sIPV group was non-inferior to the IPV group. The incidence of solicited and unsolicited adverse reactions (ARs) was similar in the pooled sIPV lots and the IPV group, and most of them were mild to moderate in severity. Non-vaccine-related serious adverse events (SAEs) were reported. Conclusions: Three consecutive lots of sIPV demonstrated robust and consistent immunogenicity. The safety and tolerability of the sIPV was acceptable and similar to that of the IPV.
Highlights
Poliomyelitis is a serious infectious disease caused by the poliovirus, which mainly affects children under 5 years old [1]
1190 (91.54%, 1190/1300) infants who completed the whole process of vaccination and blood sample collection before and after immunization within the time window were included in the per-protocol population for immunogenicity analysis
The 95% confidence interval of the geometric mean titer (GMT) ratio between each pair of strain-based inactivated poliovirus vaccine (sIPV) lots all fell into the equivalence range, which proved that the three lots of sIPV reached the lot consistency criteria
Summary
Poliomyelitis (polio) is a serious infectious disease caused by the poliovirus, which mainly affects children under 5 years old [1]. The largest developing country in the world, has incorporated polio vaccines into its national routine program since 1982 and was declared polio-free in 2000 [4]. The oral poliovirus vaccine (OPV) and inactivated poliovirus vaccine (IPV) are two types of polio vaccines that have been widely implemented worldwide to eradicate poliovirus [6]. To end polio, including VAPP, cVDPV and iVDPV, as encouraged by the Polio Eradication and Endgame Strategic Plan 2013–2018 of GPEI [9], many high- and middle-income countries have switched their routine vaccination schedules from OPV-only to a sequential IPV-OPV or IPV-only for polio prevention [10]. The Sabin-strain-based inactivated poliovirus vaccine (sIPV) plays an important role in poliomyelitis eradication in developing countries. As part of the phase III clinical development program, this study aimed to evaluate the safety, immunogenicity and lot-to-lot consistency of the sIPV in 2-month-old infants. The ratios of GMTs for poliovirus types 1, 2 and 3 of each pair of lots were all between 0.67 and
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