Field trial of combined yellow fever and measles vaccines among children in Nigeria.

The compared tolerance and immunogenecity of yellow fever and measles vaccines administered separately or combined were evaluated in Nigerian children aged between six to eight and nine to twelve months. The vaccines were well tolerated by both age groups of children, however pyrexia which responded to analgesic was the commonest post vaccination reaction in all the groups of the vaccinated children. Immune response to the vaccines either when given separately or combined was excellent in all the vaccinated groups. Antibody titre and seroconversion rate were always higher in the group that received the combined vaccines together. Our results confirmed that combined yellow fever and measles vaccines are safe for children aged between six to twelve months and we therefore recommend that yellow fever be incorporated into the EPI programme and be given together with measles at the age of nine months.