While vaccine hesitancy has been listed as a threat to world health by the World Health Organization, some are suggesting that is not the only reason why people are choosing not to vaccinate their children. While we know there are many adults who are anti-vaxx out of unfounded concerns about the safety of vaccines, some doctors are pointing out that there are socio-economic reasons that many children are missing their vaccinations, leaving them vulnerable to disease.

Dr. Melanie Seifman told NPR that she often sees children missing their scheduled vaccines, but not because their parents are anti-vaxx. The doctor works in a low-income area of Washington DC where the majority of her patients are African American and explains that there are a variety of reasons, including "transportation, couldn't get off work, didn't have insurance and didn't know that they could come in without insurance," as why many children miss their scheduled vaccines.

Dr. Seifman told NPR she's happy that Washington hasn't yet seen a measles outbreak like that in New York, and that if it did happen, the cause would be more from "just inadequate vaccination because they're just not coming in, and not because of the anti-vaccine group, just because I don't see so many of those kids."

A study published in 2015 showed that it's not only toddlers who are missing out on their vaccines, but uninsured adolescents are also missing out on needed vaccines that ensure their health and safety.

Dr. Holly Hill with the Center for Disease Control and Prevention (CDC) said that socio-economic factors are affecting children throughout the country. "We see large coverage gaps among children who are living below the poverty line compared to those at or above poverty and among children who have no insurance," says Hill. "The highest disparity is among the uninsured compared to those with private insurance."

The CDC created a federally funded vaccine program for children in 1990 to provide vaccines to children at no cost, yet Hill told NPR that the CDC needs to "find ways to make it work better for more kids." The lack of vaccinated children, especially considering the vaccination rate against measles in Washington DC is only at 81%, is a cause for concern. Officials from the department of health say they on "high alert" and doing all they can to get the word out there are ways for children to get the vaccines they need without insurance.

READ NEXT: Cases Of Measles In The U.S. Have Already Hit A Troubling High