Abstract
BackgroundDespite 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.MethodsThis 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.ResultsDuring 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.ConclusionMajority 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.
Highlights
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
Measles, mumps, and rubella (MMR) are communicable viral illnesses that are preventable through vaccination
A mild exanthematous illness, can be a real threat when infecting pregnant women especially in the first trimester and can result in fetal loss or devastating multiple anomalies known as congenital rubella syndrome (CRS) [6, 7]
Summary
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. This study was designed to determine the seroconversion rates to measles- mumps- rubella (MMR) vaccine currently in use among Iranian children. Mumps, and rubella (MMR) are communicable viral illnesses that are preventable through vaccination. Measles is a highly contagious infection that can be transmitted to more than 90% of susceptible subjects and is still a major cause of death among children, in children less than 5 years old [1]. An acute contagious disease, most often affects susceptible children to young adults in the closed crowded community and can be associated with serious complications such as: meninigoencephalitis, orchitis, pancreatitis, myocarditis, and nephritis [4, 5]. A mild exanthematous illness, can be a real threat when infecting pregnant women especially in the first trimester and can result in fetal loss or devastating multiple anomalies known as congenital rubella syndrome (CRS) [6, 7]
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