Background. Measles is the major killer among vaccine preventable diseases with an estimated one million deaths/year in developing countries. Though a good vaccine exists, the current immunization strategy of one dose at 9 months is far from optimal; too many children get measles before the age of immunization, coverage is too low when immunization has to wait until 9 months of age, and the protective efficacy is insufficient with the current vaccine given at 9 months of age. There is therefore a need for alternative immunization strategies or new vaccines.