Comparison of Immunogenicity of Inactivated Poliovirus Vaccine (IPV) Administered Intramuscularly or Intradermally

Polio is an acute transmissible disease caused by any of the three polio virus serotypes (types 1, 2 or 3). In Mozambique, polio vaccination is part of the immunization schedule of the expanded vaccination program. The oral vaccine (OPV) is administered at months 0,2,3, and 4 and a single dose of the inactivated poliovirus vaccine (IPV) is given intramuscularly at month 4. In 2016 shortage of IPV supply caused stock-outs and put strain on IPV use for routine immunizations as well as for poliovirus outbreak response. Therefore, assessment of new vaccine regimens using smaller doses of IPV are needed. Administration of fractionated IPV (fIPV), i.e., 1/5 (0.1mL) of the standard dose, intradermally has shown to be safe and to provide an immune response similar to the standard dose of IPV that is currently given intramuscularly. However, intradermal administration of fIPV is technically difficult and many countries are hesitant to adopt fIPV in their routine immunization schedules. Therefore, the investigators need data confirming that the use of the fIPV vaccine intramuscularly is safe and the immune response is not inferior to the use of fIPV intradermally. Study Objective: to compare the immunogenicity of fIPV administered intramuscularly or intradermally in infants at 2 and 4 months of age. Study Hypotheses: the seroconversion rate after administration of one or two doses of fIPV intramuscularly is not inferior to the fIPV intradermally. The priming effect after fIPV administered intramuscularly is not inferior to the fIPV intradermally. Study Methods: This will be a phase II non-inferiority clinical trial. 360 children will be enrolled in two study groups, with prior consent of the parents / guardians. In group I, 180 children will receive 0.1 ml of IPV intramuscularly and in group II 180 children will receive the same dose intradermally. There will not be a group control. The children will be selected at birth at pre-defined health units in Maputo city. The fractio