HealthDay News — Intestinal immunity improved in children after a single inactivated poliovirus vaccine (IPV) who had previously been vaccinated with oral poliovirus vaccine (OPV), according to researchers.
“Inactivated poliovirus vaccine (IPV) does not induce an intestinal mucosal immune response, but could boost protection in children who are mucosally primed through previous exposure to OPV,” explained Jacob John, MD, of the Christian Medical College in Vellore, India, and colleagues in The Lancet.
Patients aged 1 to 4 years (n=450) who had not received IPV before had their last dose of OPV at least six months prior to enrollment were involved in an open-label, randomized controlled trial. The patients were randomly assigned to either receive 0.5 ml IPV intramuscularly or no vaccine. The proportion of children shedding poliovirus seven days after a challenge dose of serotype 1 and 3 bivalent OPV was measured as the primary outcome.
Patients in the IPV group shed serotype 1 poliovirus and serotype 3 poliovirus 12% and 8%, respectively, compared with 19% and 26% in the no vaccine group (risk ratios, 0.62; P=0.0375 and 0.30 P< 0.0001, respectively). There were no study intervention-related adverse events.
“The substantial boost in intestinal immunity conferred by a supplementary dose of IPV given to children younger than 5 years who had previously received OPV shows a potential role for this vaccine in immunization activities to accelerate eradication and prevent outbreaks of poliomyelitis,” concluded the researchers.