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Younger age at measles vaccination linked to increased risk for disease
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SAN FRANCISCO — Children who received the two-dose measles vaccination at an earlier age had a significantly elevated risk for measles infection during adolescence. Therefore, researchers from Canada concluded that the optimal two-dose schedule needed for measles elimination may require further evaluation, according to study data presented here at the 52nd Interscience Conference on Antimicrobial Agents and Chemotherapy.
Gaston De Serres
An earlier outbreak investigation revealed that adolescents who received two doses of measles vaccine beginning at 12 to 14 months of age were at nearly threefold higher risk for measles infection compared with patients whose two-dose series began at 15 months of age or older, according to Gaston De Serres, MD, PhD, from The Quebec National Institute of Public Health and Laval University in Quebec, who presented the data.
Based on those study results, De Serres and colleagues conducted a matched case-control study that included 61 patients and 305 controls. In their study, the risk for measles was at least sixfold higher when the first dose was administered at 12 to 13 months of age (OR=6.24, 95% CI, 1.3-29.3) compared with 15 months of age or older; at 14 months, the OR was 1.88 (95% CI, 0.24-14.9). Results were similar when adjusted for age at second dose or interval between doses.
The current study included only patients who received two doses of measles vaccine, and all confirmed measles cases occurred among patients aged 8 to 17 years reported in the province from outside the original high school study. Mothers of cases included in this study were most likely previous ly infected by measles and have transferred higher level of antibodies to their child during pregnancy. These antibodies protect the child in the first months of life but, if they are still present at time of vaccination, they can kill the vaccine virus and prevent the child to develop a vaccine-induced protection. As most women currently giving birth are vaccinated and transfer less measles antibody to their child reducing the possibility of interference, the study results may not apply to their infants
For more information:
De Serres G. #G-876b. Presented at: 52nd ICAAC; Sept. 9-12, 2012; San Francisco.
Disclosure: De Serres reports receiving research funds from GlaxoSmithKline and Sanofi-Pasteur.