Oral iodine supplementation does not reduce neutralizing antibody responses to oral poliovirus vaccine.

ABSTRACT

Iodine deficiency is a major cause of impaired mental development, goitre, and cretinism in many parts of the world. Because existing immunization programmes can be used to deliver oral iodized oil (OIO) to infants at risk, it was important to know whether OIO could adversely affect the antibody response to vaccines, such as trivalent oral poliovirus vaccine (OPV). A randomized, double-blind, placebo-controlled clinical trial was conducted in Subang, West Java, Indonesia, in which 617 eight-week-old infants received either OIO or a placebo (poppy-seed oil) during a routine visit for their first dose of OPV as part of the Expanded Programme on Immunization (EPI). The infants received two boosters of OPV at 4-week intervals after the first dose, and were followed up when 6 months old. Neutralizing antibody titres to poliovirus serotypes 1, 2, and 3 were compared in serum samples that were taken from 478 of these infants just before the first dose of OPV and at 6 months. It was found that oral iodized oil did not reduce the antibody responses to any of the three serotypes of OPV. These results indicate that oral iodine may safely be delivered to infants at the same time as oral poliovirus vaccine according to current EPI immunization schedules.

ABSTRACT

PIP This is a randomized, placebo-controlled clinical trial on the effect of oral iodized oil (OIO) on the immune response to oral poliovirus vaccine (OPV). 617 8-week old infants were enrolled in the study conducted in Subang, West Java, Indonesia. Infants received either IOI--at which time they also received OPV and diphtheria-pertussis-tetanus vaccine--or a placebo (poppy seed oil) during their first Expanded Program on Immunization (EPI) contact for their first dose of OPV. After the first dose, 2 boosters of OPV were received by the infants at 4-week intervals, and there was a final follow-up evaluation when infants reached their 6th month. Serum samples were collected from each infant at enrolment and at follow-up. A total of 478 pairs of pre-immune and postimmune sera were collected for evaluation. Neutralizing antibody titers to poliovirus serotypes 1,2, and 3 were compared in serum samples. The range of measured neutralizing antibody activity was 0.01-14 IU for type 1, 0.05-49 IU for type 2, and 0.01-11 IU for type 3 poliovirus. After the immunization, 2 (0.4%), 1 (0.2%), and 16 (3.3%), respectively, of the infants had no detectable neutralizing antibodies to all 3 poliovirus serotypes. It was found that OIO did not reduce the antibody responses to any of the 3 serotypes of OPV but did improve infant survival in the same cohort. These findings indicate that oral iodine supplementation may be safely combined with the delivery of the first dose of OPV according to EPI schedules.