Sero-surveillance of Measles in Iranian Army Students after Nationwide Revaccination in 2004

Background: Decay of vaccine–induced antibody titres without boosting of the wild measles virus has been well documented. Revaccination against measles has reduced the prevalence of the disease worldwide. Revaccination may cause IgE induced anaphylaxis. Objective: To study measles IgG antibody in revaccinated populations and its relation to IgE induced hypersensitivity. Methods: Blood samples were taken from 800 volunteer army students aging from 18-22 years after one month of nationwide revaccination in Tehran in the year 2004. Sera were collected and kept frozen until used. Anti-measles IgG antibody and total IgE antibody were measured by ELISA assay. Results: Data indicated that only 2.37% of subjects were negative for measles antibody (titre less than 500) after a single dose of booster vaccination. From those individuals with positive IgG, 200 cases (25%) had antibody titres over 5000 IU/ml. The results showed a maximum IgE antibody titre of 1000 IU/ml (p<0.02) in which thirty cases (3.75%) had IgE titres over 1000 IU/ml (p<0.02). Conclusion: Single vaccination against measles during childhood is not sufficient for protecting against measles virus and revaccination is needed to recall specific immunity, although like other viral infections it may trigger IgE antibody responses in a small percentage of the population