Infants aged 6 weeks to 11 months, who had received <3 doses of OPV and had mild-moderate diarrhea or no diarrhea, were recruited at five health facilities in Nepal. Neutralizing antibody titers to poliovirus types 1 and 3 were measured before and 28 days after bOPV administration. The effect of diarrhea and other factors on seroconversion or boosting in antibody titers to poliovirus was assessed by multivariable analysis.
Infants with diarrhea, versus those without diarrhea, had reduced response for poliovirus types 1 (56% [87/156] vs 66% [109/164]) and 3 (34% [70/209] vs 52% [122/236]). After adjusting for other factors, infants with diarrhea had significantly reduced response for type 3 (odds ratio [OR] = 0.44, 95% CI 0.29–0.68), as did infants with >5 loose stools per day (OR = 0.36, 95% CI 0.21–0.62).
Diarrhea reduced the immune response to bOPV. Provision of additional doses of polio vaccine is necessary to maintain high population immunity in areas with high prevalence of diarrheal disease.
This study is registered at clinicaltrials.gov as NCT01559636.