Immunogenicity study for tetra and penta component vaccines in infants

ABSTRACT

A randomized controlled trial to evaluate the immunogenicity of combined Hemophilus Influenzae type b with DTP +/- injectable polio vaccine and the immunogenicity of giving one injectable polio vaccine combined with the first of 3 doses of oral polio vaccine. After parental consent, infants were randomized into 4 groups to receive the following vaccines; First group Single Hemophilus Influenzae type b vaccine [PRP-T, Act-HIB[registered] in addition to DPT and oral polio vaccine. Second group Combined [PRP-T+DTP] TETRAct-HIB[registered] and oral polio vaccine. Third group First dose is combined [PRP-T+DPT+injectable polio vaccine] PENTAct-HIB[registered] and oral polio vaccine. Then, the 2nd and 3rd dose is TETRAct-HIB[registered] and oral polio vaccine. Fourth group DPT and oral polio vaccine only [Control group]. Vaccines were given at 6 weeks, 3 months and 5 months. Blood samples were collected from all children, one month after the 3rd dose at the age of 6 months. Samples were sent for laboratory assay for anti-PRP, Diphtheria anti-toxin, Tetanus anti-toxin, polio antibody type 1, 2 and 3 and pertussis Agglutinins. Single Hemophilus Influenzae type b vaccine produced a higher anti-PRP level [15 ug ml[-1]] compared to combined Hemophilus Influenzae type b vaccine, [9.5 ug ml[-1]] in the second group and [11 ug ml[-1]] in the 3rd group but without significant level. It was found that 90% of non-vaccinated children in our sample are lacking the protective level against Hemophilus Influenzae type b diseases. Giving injectable polio vaccine with oral polio vaccine in the first of 3 doses did not affect the level of polio antibody for the 3 poliovirus types but positivity after the 3 polio doses increased compared to previous studies. In the 4 groups, 100% of the children achieved the protective level against Pertussis, Tetanus and 95% for Diphtheria. No significant negative interaction was found between vaccine antigens used in the study. Combined vaccines are effective methods to include Hemophilus Influenzae type b and injectable polio vaccine in the Extended Program of Immunization without unacceptable decrease in immunogenicity of each component