Getting a flu shot could help save the US $5.8 billion

If you haven't gotten your seasonal flu shot yet, here's a multi-billion-dollar reason to get it.

A $4 modeled just how much unvaccinated adults cost the US economy (either in healthcare costs or in loss of productivity).

The researchers found that the overall cost of 10 vaccine-preventable diseases was $8.95 billion in 2015. Those who weren't vaccinated accounted for 80% of that (about $7.1 billion).

The flu alone accounted for $5.8 billion of the costs. The next costliest disease was pneumonia, which cost the health system $1.86 billion in 2015.

Notably, the study was funded by Merck, a pharmaceutical company that makes flu vaccines among others.

Here's a breakdown of the costs:

Flu season, according to the Centers for Disease Control and Prevention, runs from $4. It's key to get the flu vaccine every flu season, $4, meaning last year's shot might not prevent you from getting this year's strain. (The current flu shot reduces your risk of catching the flu by about $4; its effectiveness varies from year to year.)

Most of that $5.8 billion cost came from inpatient costs of treating those who came down with the flu and had to go to the hospital, followed by the costs of treating those who came down with the virus outside the hospital.

"We hope our study will spur creative health care policies that minimize the negative spillover effects from people choosing not to be vaccinated while still respecting patients' right to make informed choices," the lead author of the study, Sachiko Ozawa, $4.