Measles vaccination: influence of age on its efficacy

Abstract

The authors compare the serologic efficacy and the clinical protection afforded by three different measles vaccination schemes in adequately nourished children in São Paulo city, Brazil. Two hundred forty two children were divided into three groups. Group A, comprising 117 children who had received the vaccine before 12 months of age and a second dose at 12 months of age or more. Group B, comprising 46 children who had received only one dose, before 12 months of age. Group C, comprising 79 children who had received only one dose, at 12 months of age or more. The geometric mean titer of antibodies in Group A was 790.1; in Group B, 251.1; and in Group C, 550.3. There was no statistically significant difference between Groups A and C. The exposure to the measles virus was probably similar in all groups, and the children in Groups A and C had similar chances of acquiring the disease after vaccination whereas in Group B the chances were higher when compared to the other two groups. The results obtained in this study favor the use, in developing countries, of a vaccination program against measles that includes an early first dose at eight months of age and revaccination after 12 months of age.

Effect of age at vaccination on the measles vaccine effectiveness and immunogenicity: systematic review and meta-analysis

“…Only 10 (24%) had an overall low risk of bias while 14 (34%) and 17 (41%) presented a moderate or high risk, respectively (Additional file 3). The main biases identified were: selection bias due to potential measles history among non-cases [39,45,54]; misclassification due to parents' definition of measles case [3,5,32,33,40,48,49,55] and differential verification of vaccination status for cases and non-cases [54]; and confounding bias due to lack of adjustment for time since vaccination [34,38,47,51,64]. Among studies included in the meta-analysis, 7 (27%) were at low, 12 (46%) at moderate, and 7 (27%) at high risk of bias.…”