Key result
Monovalent type 2 oral poliovirus vaccine (mOPV2) challenge in IPV-vaccinated children resulted in 50% viral shedding after one dose and 24% after a second dose, indicating intestinal immunity.
Why the study?
Understanding immunogenicity and safety of mOPV2 in IPV-immunized children is important to inform global policy for controlling circulating vaccine-derived poliovirus outbreaks.
Does mOPV2 challenge induce intestinal immunity and reduce viral shedding in IPV-vaccinated children?
RCT (n=100)
Open-label
Randomized
Does mOPV2 challenge induce intestinal immunity and reduce viral shedding in IPV-vaccinated children?
In IPV-vaccinated children, an initial mOPV2 dose induces intestinal immunity, substantially reducing viral shedding upon subsequent exposure.
Answers are grounded in this paper and cite their sources.
mOPV2 induces intestinal immunity and halves shedding on re-exposure in IPV-vaccinated children; confirms sequential OPV boosts mucosal protection for eradication.
BACKGROUND: Understanding immunogenicity and safety of monovalent type 2 oral poliovirus vaccine (mOPV2) in inactivated poliovirus vaccine (IPV)-immunized children is of major importance in informing global policy to control circulating vaccine-derived poliovirus outbreaks. METHODS: In this open-label, phase 4 study (NCT02582255) in 100 IPV-vaccinated Lithuanian 1-5-year-olds, we measured humoral and intestinal type 2 polio neutralizing antibodies before and 28 days after 1 or 2 mOPV2 doses given 28 days apart and measured stool viral shedding after each dose. Parents recorded solicited adverse events (AEs) for 7 days after each dose and unsolicited AEs for 6 weeks after vaccination. RESULTS: After 1 mOPV2 challenge, the type 2 seroprotection rate increased from 98% to 100%. Approximately 28 days after mOPV2 challenge 34 of 68 children (50%; 95% confidence interval, 38%-62%) were shedding virus; 9 of 37 (24%; 12%-41%) were shedding 28 days after a second challenge. Before challenge, type 2 intestinal immunity was undetectable in IPV-primed children, but 28 of 87 (32%) had intestinal neutralizing titers ≥32 after 1 mOPV2 dose. No vaccine-related serious or severe AEs were reported. CONCLUSIONS: High viral excretion after mOPV2 among exclusively IPV-vaccinated children was substantially lower after a subsequent dose, indicating induction of intestinal immunity against type 2 poliovirus.
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Bandyopadhyay et al. (2020) conducted an RCT in Poliovirus immunity in IPV-vaccinated children (n=100). Monovalent type 2 oral poliovirus vaccine (mOPV2) was evaluated on Stool viral shedding 28 days after first mOPV2 challenge (95% CI 38-62). Monovalent type 2 oral poliovirus vaccine (mOPV2) challenge in IPV-vaccinated children resulted in 50% viral shedding after one dose and 24% after a second dose, indicating intestinal immunity.
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