Key result
An oral poliovirus vaccine challenge dose resulted in PV1 excretion in 14% (81/589) of children at 7 days, with 86% of excretors being seropositive at baseline, indicating waned mucosal immunity.
Why the study?
The study was conducted to assess poliovirus type 1 immunity in children to inform the contribution of mucosal immunity in and prevention of poliovirus circulation.
What is the rate of poliovirus type 1 excretion following OPV challenge in children in Karachi, Pakistan?
Cross-Sectional (n=610)
What is the rate of poliovirus type 1 excretion following OPV challenge in children in Karachi, Pakistan?
Despite humoral immunity, a significant proportion of children in Karachi lack mucosal immunity to poliovirus, allowing for asymptomatic shedding and potential transmission.
Answers are grounded in this paper and cite their sources.
Seropositive children may still shed poliovirus if mucosal immunity waned; leaves open need for targeted mucosal boosting in eradication efforts.
This study assesses poliovirus type 1 (PV1) immunity in children to inform the contribution of mucosal immunity in and prevention of poliovirus circulation. A community-based study was conducted in periurban Karachi, Pakistan. Randomly selected children (0-15 years of age) received oral poliovirus vaccine (OPV) challenge dose. Blood and stool samples were collected at several time points and evaluated for polio-neutralizing antibodies and serotype-specific poliovirus, respectively. Eighty-one of 589 (14%) children excreted PV1 7 days post-OPV challenge; 70 of 81 (86%) were seropositive at baseline. Twelve of 610 (2%) were asymptomatic wild poliovirus type 1 (WPV1) excretors. Most poliovirus excretors had humoral immunity, suggesting mucosal immunity in these children likely waned or never developed. Without mucosal immunity, they are susceptible to poliovirus infection, shedding, and transmission. Asymptomatic WPV1 excretion suggests undetected poliovirus circulation within the community.
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Saleem et al. (2024) conducted a cross-sectional in Poliovirus immunity (n=610). Oral poliovirus vaccine (OPV) challenge dose was evaluated on PV1 excretion 7 days post-OPV challenge. An oral poliovirus vaccine challenge dose resulted in PV1 excretion in 14% (81/589) of children at 7 days, with 86% of excretors being seropositive at baseline, indicating waned mucosal immunity.
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