A new study conducted by the Johns Hopkins Bloomberg School of Public Health shows that vaccinating poor children against measles significantly improves their long-term chances for survival and dramatically reduces inequities in child health and survival. The study was conducted among children living in Bangladesh and is published in the June 2001 issue of Population and Development Review.
"Unvaccinated children from poor families are three times more likely to die before age 5 compared to vaccinated children from families of higher socioeconomic status," says the study's author Michael Koenig, PhD, MA, associate professor of population and family health sciences at the Johns Hopkins Bloomberg School of Public Health.
"Our research shows that measles vaccine decreases the mortality rate for children of poor families more than 50 percent, bringing it much closer in line with the mortality rate of children of wealthier families. In contrast, there was only a small differential in survival between vaccinated and unvaccinated children of higher socioeconomic status," explains Dr. Koenig.
For the study, researchers examined longitudinal data collected from the International Centre for Diarrhoeal Disease Research (ICDDR,B) in Matlab, Bangladesh. The researchers analyzed data from 8,135 children who received the measles vaccine between March 1982 and October 1985.
The children were matched with controls to determine whether the measles vaccine improved the long-term survival of vulnerable children, which included children of low socioeconomic status, females, and children of mothers with little education.
According to the research results, measles vaccine had the greatest impact on reducing the health and survival inequities of the most vulnerable children, especially children of lower socioeconomic status.
Vaccinated children from the poorest households--those living in homes less than 200 square feet--were 50 percent less likely to die than those children of the same socioeconomic status. Differences in the mortality rate between vaccinated and unvaccinated children became less significant as socioeconomic status improved.
Female children living in Bangladesh are especially vulnerable and have a higher mortality rate than male children. The results also show that vaccinating female children for measles significantly raised their chances of survival overall, bringing them to almost the same mortality rate as unvaccinated males. However, the difference in survival rate between vaccinated and unvaccinated girls was in proportion to the increase in survival between vaccinated and unvaccinated boys, and was therefore not statistically significant.
The study by Dr. Koenig and colleagues does not address why measles vaccine provides this disproportionate benefit to more vulnerable children. They hypothesize that the vaccine may stimulate the immune system in non-specific ways. Measles has a devastating effect on children with poor nutrition and the disease can also lead to prolonged infections, both of which may be more of a factor among children of low socioeconomic status. The researchers say more research is needed to determine if the health equity effect also applies to other child survival interventions as well.
"Measles vaccine is not a new technology, but in many countries vaccine coverage is as low as 50 percent. The majority of the unvaccinated children are from the most vulnerable social and economic groups, yet these are the children who could benefit the most from measles vaccination. Our findings make a compelling case for developing targeted programs and policies to ensure that measles vaccine reaches the most disadvantaged children to further reduce inequities in child survival," adds Dr. Koenig.
David Bishai, MD, MPH, and Mehrab Ali Khan, MA, assisted in the research of the study. Funding for the study was provided by Centre for Health and Population Research and the Global Forum for Health Research.
Reporters note: the Johns Hopkins Bloomberg School of Public Health will be closed on July 4, 2001.