Charlottesville, VA (PRWEB) January 14, 2014
Researchers at the University of Virginia School of Medicine and their collaborators have identified why oral vaccinations for polio and rotavirus are far less effective in the developing world than in the West. The culprits: malnutrition, diarrhea and abbreviated breastfeeding.
Polio vaccines given orally to children in the developing world are only about half as effective as in the United States. Until now, doctors were unsure why that was the case. The new research not only sheds light on the matter but points to simple strategies that could help overcome the problem, a major roadblock in the international effort to eradicate polio around the world.
The researchers followed children in an urban slum of Dhaka, Bangladesh, from birth to one year. Those children in which the vaccine proved ineffective tended to share certain characteristics.
“Children who had two or more episodes of diarrhea were twice as likely to fail polio vaccination. Malnourished children, and children who were weaned early from exclusive breastfeeding, were also more likely to have a poor response to vaccination,” explained William Petri Jr., MD, PhD, chief of UVA’s Division of Infectious Diseases and International Health. “While our observations need to be validated and extended at other regions of the developing world, they are encouraging to me as they suggest that very simple interventions, such as promoting exclusive breastfeeding, can improve vaccination and hasten eradication of polio.”
The factors associated with oral vaccine ineffectiveness are common in developing countries, Petri noted. Up to 40 percent of children there are undernourished, diarrhea is a leading cause of death, and breastfeeding is often of shortened duration, he said. Notably, oral vaccines have a much higher failure rate than ones given by injection – suggesting another potential approach to surmounting the problem.
“It is remarkable to have the opportunity to discover the reasons why a vaccine that is one of the most commonly administered worldwide does not always work properly,” Petri said.
The findings have been published online by the journal Vaccine and will appear in a forthcoming print edition. The article was authored by Rashidul Haque, of the International Centre for Diarrhoeal Disease Research in Dhaka, Bangladesh; UVA’s Cynthia Snider, Yue Liu and Jennie Z. Ma; Lei Liu of Northwestern University; UVA’s Uma Nayak, Josyf C. Mychaleckyj and Poonum Korpe; Dinesh Mondal, Mamun Kabir and Masud Alam, of the International Centre; Mark Pallansch, M. Steven Oberste and William Weldon, of the Centers for Disease Control and Prevention; Beth D. Kirkpatrick, of the University of Vermont College of Medicine; and Petri.