More than 8 million US children, adolescents susceptible to measles
SAN DIEGO — Analysis of measles vaccination coverage data in the United States indicated that one in eight children and adolescents are at risk for measles infection, making the entire population vulnerable to widespread outbreaks, according to a presentation at IDWeek 2015.
“I think it’s important to point out that these results are not either totally alarming nor totally reassuring,” researcher Robert Bednarczyk, PhD, of the departments of global health and epidemiology at the Rollins School of Public Health, Emory University, told Infectious Diseases in Children. “Right now, we are seeing measles immunity levels that are sufficient to prevent sustained transmission, just as we have since 2000. But, the buffer that we have before we reach insufficient immunity levels is not very large, and we need to not get complacent. All children who are medically able to receive measles vaccine should be vaccinated at the recommended schedule.”
Bednarczyk and colleagues reviewed the National Immunization Survey-Teen, a poll of provider-verified responses regarding children and adolescents. This data was used to estimate the number of children currently susceptible to measles infection, as well as gauge vaccination effectiveness, infant protection from maternal vaccination, and waning of immunity after cancer treatment.
Data showed that 12.5% of children and adolescents aged 17 years or younger, or 8.7 million individuals, were at risk for measles. Children aged 3 years or younger were at the greatest risk, with 24.7% susceptibility. The researchers also found that nearly 5% of adolescents aged 17 had not received any type of measles-containing vaccine.
The investigators emphasized that a reduction in coverage to 98% of the current levels would make an additional 1.2 million adolescents and children vulnerable to measles, due to insufficient coverage to meet herd immunity levels for any age range. According to study findings, the current measles vaccination rate is 92% to 94%, the threshold for susceptibility for widespread measles illness.
“Moving forward, we need to evaluate these immunity estimates in smaller geographic areas, and use these estimates as a baseline for program planning to ensure sustained sufficient measles vaccination,” Bednarczyk said. – by David Costill
Bednarczyk R, et al. Poster 1866. Presented at: IDWeek; Oct. 7-11, 2015; San Diego.
Disclosure: The researchers report no relevant financial disclosures.