Post-Vaccination Immunity Against Measles in Under Twenty-Five-Year-Old Population of Ahvaz, Southwest of Iran

Abstract

Background: Measles is a severe contagious disease, preventable by vaccination. The Ministry of Health and Medical Sciences of Islamic Republic of Iran, has launched a mass Measles vaccination campaign throughout the country from 2003. More than 32 million inhabitants between 5 and 25 years old received the measles vaccine. Objectives: The purpose of this study was to determine the prevalence of positive measles antibody titers in target groups (subjects under 25 year olds) who had received mass vaccination. Patients and Methods: We conducted this cross-sectional study on 900 subjects (363 males and 537 females), referred to health care and medical center of Ahvaz during 2011. Measles IgG antibody of serum was measured using the ELISA method. Results: Overall, 821 (91.2%) of the studied population under 25 years, had immunity to measles. Among girls and boys, 92.2% and 89.8% were seropositive, respectively. These differences were not statistically significant between the two sexes (P = 0.133). Anti-measles antibody titer increased with the increase of age from ≤ 5 to 21 - 25 years (87.3% in ≤ 5-year-old group vs. 96.5 in 21 to 25-year-old group). These differences were statistically significant between the age groups (P = 0.021). Conclusions: Results indicated that the present vaccination program is insufficient for immunity against measles in this area. The general population immunity was lower than the necessary level for the elimination of measles. Therefore, sero-epidemiological studies are necessary to organize national programs for control and elimination of measles.