"The cost of revaccinating these children is substantial and may impact parents, physicians and vaccine purchasers," say Shannon Stokley, M.P.H. of the Centers for Disease Control and Prevention and colleagues. Their findings appear in the January issue of the American Journal of Preventive Medicine.
Stokley and colleagues' sample of national immunization records reveals that 10 percent of children received at least one invalid vaccine dose in 2002. Invalid vaccines are doses administered five or more days before the minimum age for the first dose or before the minimum time between doses has elapsed.
Invalid doses need to be repeated to ensure that children are adequately protected from disease, according to the researchers.
"It is important that vaccines be administered at an age when a child can develop a proper immune response and before significant exposure to natural infection," Stokley says.
Of the 2002 incorrect doses, half were for the hepatitis B vaccine, 19 percent were for diphtheria-tetanus-pertussis, 15 percent for chicken pox, 12 percent for measles and only 4 percent for polio.
The first and final doses in a vaccine series were the ones most likely to be given too early, the researchers found. For instance, all of the incorrect hepatitis B doses were the the third and final dose. First doses made up 98 percent of all invalid polio vaccinations.
Children who received vaccinations from multiple healthcare providers and those who were born outside the United States were more likely to get an invalid dose. American Indian, Hispanic and Asian children were also significantly more likely to get an invalid vaccination.
Children with mothers who had completed at least some college were less likely to get incorrect doses than those with mothers who had not completed high school, Stokley and colleagues concluded.
The study included immunization data collected from 34,087 parents and 22,958 physicians for children ages 19 to 35 months.
By Becky Ham, Science Writer
Health Behavior News Service
FOR MORE INFORMATION
Health Behavior News Service: 202-387-2829 or www.hbns.org.
Interviews: Contact Shannon Stokley at sstokley@cdc.gov.
American Journal of Preventive Medicine: Contact the editorial office at 858-457-7292.
Journal
American Journal of Preventive Medicine