Parents who fail to vaccinate their kids, or who don't give them the required follow-up injections, are putting one in eight children in the U.S. at risk of getting measles, according to a new analysis. The researchers found that nearly 9 million children are susceptible to the disease, which can lead to pneumonia, encephalitis, and even death. Exempting those who cannot be vaccinated due to medical reasons, the scientists continue to urge all parents to make sure their children are fully protected.
“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. Robert Bednarczyk, lead author of the study presented at IDWeek 2015, the annual meeting of the Infectious Diseases Society of America. “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.”
The recent analysis found that the percentage of children immune to measles is close to the minimum needed for effective herd immunity, which is the lowest number of people needed to be vaccinated to provide indirect protection from infectious disease from those who are not vaccinated. Below this threshold, outbreaks of measles will become far more likely, leading to widespread illness. This is especially a concern as unvaccinated children tend to cluster in communities, where the disease could easily spread.
Despite having stopped continuous measles transmissions in the U.S. over 15 years ago, Bednarczyk said “these study results show that we can't get complacent.” They found that 12.5% of all children aged from newborn to 17 years old were not fully protected, though this figure jumps to almost 25% for those under three years old. The vaccine for measles is usually coupled with those for mumps and rubella in what’s known as the MMR vaccine, and should be given to children in two doses – the first between 12 and 15 months of age, and the second between the ages of four and six.
While Bednarczyk says that he doesn’t find these results particularly alarming, he doesn’t find them reassuring either. This is because if the current rate of vaccination drops by just 2%, it could put another 1.2 million children at risk of catching measles. “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,” he said in the statement.