Background Despite high rate of vaccination coverage with 2-doses of measles containing vaccine among Iranian children, outbreaks of measles occurred among different age groups and fully vaccinated subjects. Although the main reason for these outbreaks is unknown, however, vaccine failure was supposed to be an important cause. This study was designed to determine the seroconversion rates to measles- mumps- rubella (MMR) vaccine currently in use among Iranian children. Methods This prospective study was conducted among healthy children older than 12 months who were candidates of scheduled MMR vaccination. Blood samples were obtained from each mother- infant pair just before vaccination, and from infants 4–6 weeks after MMR1 and MMR2 immunization. Collected sera were tested for specific lgG antibodies against MMR agents using ELISA method. The proportion of seroprotected subjects among mother- infant pairs before vaccination as well as the prevalence rates of seroconversion after MMR1 and MMR2 vaccination were calculated. Collected data were analyzed using descriptive statistical methods. Results During 22-months study period, 92 mother- infant pairs were participated. Seroimmunity rates against MMR viruses were 85.8%, 84.7% and 86.9% for mothers, and 3.2%, 2.1% and 1.0% for children, respectively. After MMR1 vaccination from 52 seronegative children, 80.7%, 78.8% and 75% were seroconverted. These rates increased to 94.8%, 89.7% and 94.8% after the MMR2 vaccination. Also, the specific immunity was enhanced among seropositive children. Conclusion Majority of the mothers and few infants were immune to MMR viruses prior to MMR1 vaccination. Immune responses detected after MMR1 injection, and overall seroconversion rates achieved after 2-doses of MMR vaccination were less than expected and inadequate to preserve long-term protection against MMR agents.

Background. Healthcare sciences students(HSS)are at the higher risk of exposure to several infections during training. The most important are measles, mumps, varicella, pertussis and influenza, that are transmitted easily via respiratory routes. These infections are vaccine preventable, and commonly are more complicated while develop during adulthood. Confirming immunity before training are recommended, however, adherence to the policy is not satisfactory universally. To evaluate immunity status, and to determine the most appropriate approach to provide full protection against these infections, this study was designed. Methods. A cross-sectional study among newly accepted HSS was conducted. Their past vaccination status, and medical history of compatible clinical diseases were sought by personal interview and self-administered questionnaire. Sera specific IgG antibodies to these infections were measured using ELISA. The relative proportion of seroimmune students were calculated. The correlation between past clinical diseases and their immune status particularly among those who showed no history of earlier vaccination were determined. The most appropriate policy to provide full protection was determined. The collected data were analyzed using descriptive statistical methods as appropriate. Results. Overall, 242 students with mean age 23.9 years, 59% female were participated. All HSS declared that they had been vaccinated according to the national immunization program. Among them 188 students with additional dose of measles- rubella (MR), and 54 by measles- mumps- rubella (MMR) vaccines were re-vaccinated.Overall seropositivity rates were as: measles-80.1%, mumps-64%, rubella-93.4%, varicella-78.5%, pertussis-46.5%, diphtheria-87.3%, and tetanus-87.2%. There were not significant differences between two groups of HSS; MR vs MMR re-vaccinated students. The most cost-benefits strategy to provide immunity against MMR agents were universal vaccination. Conclusion. Nearly 63%of HSS were susceptible to MMR viruses, and universal MMR vaccination of the students just before training was the most appropriate policy to provide immunity. Efforts should be made to incorporate adult-type acellular pertussis vaccine to diphtheria- tetanus toxoids to and varicella vaccine provide protection against these agents.

Background. Despite high rate of vaccination coverage with 2-doses of measles vaccine among Iranian children, outbreaks of measles occurred among different age groups and fully vaccinated subjects. Although the main reason for these outbreaks is unknown, however, vaccine failure was supposed to be an important cause. This study was designed to determine the immunogenicity of measles- mumps- rubella (MMR) vaccine currently in use among Iranian children.Methods. This prospective study was conducted among ³ 12 month- old healthy children who were candidates of scheduled MMR vaccination. Blood samples were obtained from each mother- infant pair just before vaccination, and from infants 4- 6 weeks after MMR1 and MMR2 immunization. Collected sera were tested for specific lgG antibodies against MMR agents using ELISA method. The proportion of seroprotected subjects among mother- infant pairs before vaccination as well as the prevalence rates of seroconversion after MMR1 and MMR2 vaccination were calculated. Collected data were analyzed using descriptive statistical methods.Results. During 22-months study period, 92 mother- infant pairs were participated. Seroimmunity rates against MMR viruses were 85.8%, 84.7% and 86.9% for mothers, and 3.2%, 2.1% and 1.0% for children, respectively. After MMR1 vaccination of 52 seronegative children, 80.7%, 78.8% and 75% were seroconverted. These rates increased to 94.8%, 89.7% and 92.3% after the MMR2 vaccination. Also, the specific immunity was enhanced among seropositive children.Conclusion. Majority of the mothers and few infants were immune to MMR viruses, prior to MMR1 vaccination. Seroconversion rates detected after MMR1 injection, and overall seroprotection rates achieved after 2-doses of MMR vaccination were less than expected and inadequate to preserve long-term protection against MMR agents.