The study, “Modeling the Economic Burden of Adult Vaccine-Preventable Diseases in the United States” estimates that the cost of treating vaccine-preventable diseases in 2015 was $9 billion, according to Health Affairs.

Unvaccinated individuals accounted for nearly 80 percent, or $7.1 billion of the $9 billion total. And the remaining $1.9 billion was attributed to those who still needed care after vaccination.

So why aren’t adults getting vaccinated?

“We’ve been really focused, especially in the vaccine world, on vaccinating children and not necessarily adults,” says Sachiko Ozawa, associate professor in the division of practice advancement and clinical education at the University of North Carolina Eshelman School of Pharmacy, Chapel Hill, and lead author of the study. This study illuminates the economic burden unvaccinated adults have on health care, she adds.

The study looked at vaccine-preventable diseases related to 10 vaccines recommended for adults 19 and older on a cost-per-case basis. Researchers looked at previous cost literature and multiple-cost data sources.

Ozawa says the challenge in increasing vaccination numbers is balancing the individual need for people to make their own choices against the need for health systems to control costs while operating rationally, effectively and efficiently.

But physicians and providers can certainly help to push vaccination numbers up.

“It’s important, that when adults come in for annual visits, to remind them that they should be getting certain vaccinations, especially the elderly, but even for adults,” says Ozawa. “[This] would ultimately reduce health care costs for the system — preventing not only diseases, but unnecessary costs.”