One Full or Two Fractional Doses of Inactivated Poliovirus Vaccine for Catch-up Vaccination in Older Infants: A Randomized Clinical Trial in Bangladesh.

BACKGROUND: The polio eradication endgame called for the removal of trivalent oral poliovirus vaccine (OPV) and introduction of bivalent (types 1 and 3) OPV and inactivated poliovirus vaccine (IPV). However, supply shortages have delayed IPV administration to tens of millions of infants, and immunogenicity data are currently lacking to guide catch-up vaccination policies. METHODS: We conducted an open-label randomized clinical trial assessing 2 interventions, full or fractional-dose IPV (fIPV, one-fifth of IPV), administered at age 9-13 months with a second dose given 2 months later. Serum was collected at days 0, 60, 67, and 90 to assess seroconversion, priming, and antibody titer. None received IPV or poliovirus type 2-containing vaccines before enrolment. RESULTS: A single fIPV dose at age 9-13 months yielded 75% (95% confidence interval [CI], 6%-82%) seroconversion against type 2, whereas 2 fIPV doses resulted in 100% seroconversion compared with 94% (95% CI, 89%-97%) after a single full dose (P < .001). Two doses of IPV resulted in 100% seroconversion. CONCLUSIONS: Our study confirmed increased IPV immunogenicity when administered at an older age, likely due to reduced interference from maternally derived antibodies. Either 1 full dose of IPV or 2 doses of fIPV could be used to vaccinate missed cohorts, 2 fIPV doses being antigen sparing and more immunogenic. CLINICAL TRIAL REGISTRATION: NCT03890497.

Seroprevalence of anti-polio antibodies in children from polio high risk area of Afghanistan: A cross sectional survey 2017.

BACKGROUND: Afghanistan is one of the remaining wild-poliovirus (WPV) endemic countries. We conducted a seroprevalence survey of anti-poliovirus antibodies in Kandahar Province. METHODS: Children in two age groups (6-11 months and 36-48 months) visiting Mirwais hospital in Kandahar for minor ailments unrelated to polio were enrolled. After obtaining informed consent, we collected venous blood and conducted neutralization assay to detect poliovirus neutralizing antibodies. RESULTS: A total of 420 children were enrolled and 409/420 (97%) were analysed. Seroprevalence to poliovirus type 1 (PV1) was 97% and 100% in the younger and older age groups respectively; it was 71% and 91% for PV2; 93% and 98% for PV3. Age group (RR = 3.6, CI 95% = 2.2-5.6) and place of residence outside of Kandahar city (RR = 1.8, CI 95% = 1.2-2.6) were found to be significant risk factors for seronegativity. CONCLUSIONS: The polio eradication program in Kandahar achieved high serological protection, especially against PV1 and PV3. Lower PV2 seroprevalence in the younger age group is a result of a withdrawal of live type 2 vaccine in 2016 and is expected. Ability to reach all children with poliovirus vaccines is a pre-requisite for achieving poliovirus eradication.

Neutralization of Enterovirus D68 isolated from the 2014 US outbreak by commercial intravenous immune globulin products.

BACKGROUND: In 2014, an outbreak of Enterovirus D68 (EV-D68) was recorded as the largest in the US with cases confirmed in 49 states. Intravenous immune globulin (IVIG) has been used to treat enterovirus infections in neonates and is an accepted replacement therapy for immunodeficient patients. OBJECTIVES: This study aimed to detect the presence of neutralizing antibodies to EV-D68 viruses from the 2014 outbreak in commercially available IVIG products. STUDY DESIGN: Commercially available lots of IVIG preparations were obtained from five different manufacturers (2-10 preparations per manufacturer) and tested for neutralizing antibodies against the prototype EV-D68 virus and three EV-D68 isolates representing strains circulating during the 2014 outbreak. RESULTS: All lots of IVIG tested were positive for EV-D68 neutralizing antibodies, with high titers ranging from 9.5log2 to 17.5log2, and with comparable median titers to all four EV-D68 viruses. CONCLUSIONS AND DISCUSSION: Amino acid sequence differences in the regions of the predicted antigenic sites on the viral capsid may explain some of the differences in neutralization among the different strains. The neutralization titers suggests that the 2014 outbreak EV-D68 viruses share some antigenic sites with the prototype virus and also present some unique antigenic sites distinct from the prototype. However, the commercial IVIG lots tested all contained high levels of neutralizing antibodies against EV-D68.