Contrary to measles vaccination, diphtheria-tetanus-pertussis (DTP) vaccination has been associated with a negative effect on child mortality. Current studies indicate that the negative effect of DTP may be neutralized by a subsequent measles vaccination. The design of the proposed trial will allow us to test whether the negative effect of the DTP vaccine, which is administered by the EPI-programme at 6, 10 and 14 weeks of age, can be reverted by administration of a measles vaccine 4 weeks after the last DTP vaccination at around 4½ months of age.