Immune response to intradermally administered inactivated poliovirus vaccine is equivalent to IM injection

In countries where control of paralytic polio (PP) due to wild poliovirus has been achieved, the interim use of inactivated poliovirus vaccine (IPV), either alone, or in combination with oral poliovirus vaccine (OPV) is one strategy to prevent vaccine associated paralytic poliomyelitis. However, the high cost of IPV has been a limitation. In order to reduce the cost of vaccination, we evaluated the imiminogenicity of a fractional dose of IPV administered intradennally (ID) to infants as primary immunization. Seventy eight healthy infants 5-8 weeks of age received ID either 2 doses of IPV 8 weeks apart (group A) or 3 doses 4 weeks apart (group B). Serum samples collected prior to the first dose of vaccination and 4 weeks after the last dose were tested for the presence and tiler of neutralizing antibody to poliovirus types 1,2 and 3. Of the 69 infants who completed the study, 30 were in group A and 39 in group B. The seroconversion rates, to poliovirus (PV) types 1,2 and 3 in infants in group A were 90%, 70% and 97%, respectively, and in group B 90%, 80% and 98%, respectively; in children without pre-existing maternal antibody, seroconversion rales, in both groups, were 100% to all 3 poliovirus serotypes. These rates are comparable to those in children receiving 5 doses of OPV (83%, 96% and 82% to PV types 1,2 and 3, respectively) or 2 doses of intramuscular IPV (95%, 79% and 96% to PV types 1,2 and 3, respectively). Intradeimal IPV may be a less costly alternative for use in poliomyelitis control programs, especially in developing countries.