Our group has discovered that routine vaccinations in childhood may have non-specific and sex-differential effects on overall mortality. The effects are so large that they may have marked effects on overall mortality and seriously distort female-to-male mortality rates in high-mortality settings. We recently experienced periods during which oral polio vaccine (OPV) was lacking. Hence, some children did not get the recommended OPV at birth. We were following all infants as a part of a vitamin A supplementation trial. Surprisingly, we discovered that not receiving OPV was associated with significantly lower mortality in boys, but not in girls. We bled a subgroup of the children. Receiving OPV at birth significantly dampened the immunological response to BCG given at birth in both sexes. Based on these observations, receiving OPV at birth may have two negative effects, first, it may increase male mortality, and second, it may interfere with immunity against tuberculosis. OPV at birth is given for logistic reasons, to boost polio immunity. There have been no polio cases in Guinea-Bissau for the last 10 years. Hence, there is every reason to test in a randomised trial whether not receiving OPV at birth is associated with 1) mortality, morbidity and growth and 2) immunological response to BCG.

Inclusion Criteria:Normal birth weight, no overt illness or gross malformations -

Exclusion Criteria:

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