RESUMO
It is well agreed that vaccination is the only effective method of preventing, and possibly eradicating poliomyelitis. Although poliomyelitis only rarely occurs in the first six months of life, some countries including Egypt started administering of a so called "zero " dose of poliomyelitis vaccine in the first 1-7 days from birth. In this study, we tried to evaluate the efficacy and beneficially of this "zero" dose of Oral Polio vaccine [OPV] in a cohort of 51 healthy full-term normal newborn Egyptian babies, 30 took the zero dose ,the zero dose "group, and 21 did not, the control group. Serum samples were collected from all babies as follows: [a] from the cord blood, the" zero sample", [b] at the age of 30 days "to test the efficacy of the zero dose", and [c] a third blood sample, 30 days after the first dose of regular OPV; at the age of three months. Antipoliomyelitis antibody titers were estimated by the micro neutralization system against the three serotypes of poliovirus [PI, PII, and PIII]. Statistical analysis of the results revealed that he mean cord blood antipoliomyelitis antibody titer for both groups taken together was highest for PI [210.85], appreciably high for PII [164.88] and comparatively low for Plll [30.05], the levels were generally lower in the "zero dose" group for the three polioviruses than in the control group, possibly due to locality differences. At the age of one month, there was an antibody rise in the "zero dose group, and a drop in the "control group". However, in spite of the drop in the control group antibody titer, it was still well above the reported protective level. We did not compare the absolute values of antibody titers in both groups at the 2nd and 3rd blood samples because of the difference in the start cord blood antibody levels, therefore, we compared the increment/decrement values, particularly the increment in the 3rd month samples in the control group with the increment in the first month in the zero dose group as these represent the primary response to the "first" dose of OPV. The increments for the primary response of the OPV were higher in the control group than in the zero dose group for PI, PII, and PIII
Conclusions: the fact that all antibody titers in the control group in all samples were above the protective level, and the findings that the increment of antibody titer for the primary OPV in the control group was higher than that of the zero dose group raises a question mark at the beneficially of the zero dose of OPV in Egyptian infants, particularly from the cost-effect point of view