Measles antibody titer in Egyptian school age children: vaccine failure and the need for a booster dose

ABSTRACT

Measles antibody titer was determined by ELISA in 136 school children selected to be in two age groups 4-6 and 10-12 years taking into consideration previous contraction of measles disease and measles vaccination. A titer >/0.20 O.D. Was considered indicative of immunity. The diseased subjects showed significantly higher antibody titers [P <0.05] in comparison with nondiseased subjects in both age groups regardless of the state of vaccination. The antibody titer did not differ significantly between diseased children aged 4-6 or 10-12 years [P >0.05], while in the nondiseased children, the antibody titer was significantly higher in the younger age group [P <0.05]. Vaccine failure was noticed more frequently in children vaccinated approximately 10 years ago [47.37%] than in children vaccinated approximately 5 years ago [21.67%]. Measles antibody titer was shown to decrease gradually as time passes after vaccination but was still protective at age 10-12 years [O.D. 0.58 +/- 0.21]. Accordingly, primary rather than secondary vaccine failure appears to be responsible for the high failure rate in the subjects. The results would strongly encourage a booster dose of measles vaccine, the optimum timing, mode of implementation and possibility of combining with a mumps and rubella vaccine should be a subject of further research