Recent studies have found administration of high-titre measles vaccine before 9 months of age to be associated with reduced survival. Since this suggests that early immunization could be unsafe, we examined the results of immunization campaigns with Schwarz standard measles vaccine carried out in 1980-1983 in three areas of Guinea-Bissau. Children were followed to death, migration or the age of five years. Children immunized at 4-8 months of age, of whom many were later re-immunized, had lower mortality between nine months and five years of age compared with children vaccinated at 9-11 months of age. The improved survival was unrelated to better protection against measles. There was no sign of socio-cultural differences between children immunized at different ages. Vaccination before 9 months of age is apparently safe and it may reduce childhood mortality compared with the currently recommended strategy of immunizing from nine months of age. Randomized trials are needed to confirm these observations which may have implications for the measles immunization strategy for developing countries.
Ugeskrift for Laeger, 1994, Vol 156, Issue 40, p. 5857-61