New research suggests that gaps in measles vaccination rates place one in eight children at risk for becoming sick from the highly contagious illness, The Boston Globe reported.
Researchers found that nearly 9 million children -- infants through 17 -- are susceptible to measles primarily because they haven't received the measles, mumps and rubella (MMR) vaccine, or have received only one of the two recommended doses.
The percentage of children immune to measles is very close to the range of 92 to 94 percent. Below this threshold, measles outbreaks are possible and could lead to widespread illness.
Measles is highly contagious and can lead to pneumonia, encephalitis, hospitalization and occasionally, death.
"Although we eliminated continuous measles transmission in the United States about 15 years ago thanks to the effectiveness of the MMR vaccine and robust vaccination rates, these study results show that we can't get complacent," Robert Bednarczyk, lead author of the study, said in a statement. "While we currently have overall immunity in the population that should prevent sustained measles transmission, if the virus is introduced, there is the potential for large outbreaks. This is because there are clusters of unvaccinated children in some communities, which could allow a large outbreak to occur with spread to similar communities."
Bednarczyk said all children should receive two doses of measles containing vaccines at the recommended ages. He noted that the biggest concern is children who haven't received any doses for any of a variety of reasons, including: lack of access, being unaware of the need for vaccines and being opposed to vaccines. In addition, doctors need to ensure those who received only one dose receive a second dose at the recommended age.
The MMR vaccine is given to children in two doses, the first at 12 to 15 months and the second at four to six years old. While children are required to receive the MMR vaccine before attending school, some are exempt because they have a medical issue, such as an immune disorder or cancer.
In their analysis, researchers determined that 12.5 percent of all children -- 8.7 million -- were not fully protected by vaccination and therefore were susceptible to measles, and that 24.7 percent of children age three or younger are at risk. Among 17-year-olds, 4.6 percent had received no doses of MMR. If the percentage of vaccinated children drops to just 98 percent of current levels, researchers estimate that 14.2 percent of children -- one in seven -- would be vulnerable to measles.
"We know some parents have concerns about vaccines and may want to avoid or delay vaccination, or follow an alternative schedule than the one recommended because they're concerned about the safety of the vaccine,'" said Dr. Bednarczyk. "In fact, the vaccine is very safe, while not vaccinating is highly risky, leaving their children -- and others -- vulnerable to a serious illness that can cause a large number of complications. Currently, these children are protected because of the high vaccine coverage of the population, but that will change if we begin having more outbreaks and the percentage of children vaccinated declines."
The findings were presented at IDWeek 2015.
