Scientists have found a way to create a polio vaccine without having to use the virus itself, a method that could reduce safety risks.

Like other vaccines, the ones for poliovirus are made using the actual virus, although it has been killed or weakened. But growing and using live virus comes with “a dangerous security risk of virus escaping into the environment,” the University of Leeds said in a statement. The new method involves using “virus-like particles” that do not contain viral genetic material. Although these particles were previously too unstable to use as a vaccine, the researchers identified genetic mutations to make the virus resistant to heat and then derived the particles from those versions to make the vaccine more stable.

Poliomyelitis, the disease humans contract when infected with poliovirus, causes fever, fatigue, nausea, headaches, stiffness in your back and neck, limb pain and in some cases paralysis, according to the U.S. National Library of Medicine. “There is no treatment to reverse the paralysis of polio.”

Read: 6 Presidents You Didn’t Know Had Chronic Medical Conditions

The disease is linked in public consciousness with images from the early half of the 20th century of children in iron lungs — precursors to modern ventilators that helped their lungs breathe — and the knowledge that President Franklin Delano Roosevelt was paralyzed in his lower half from the infection.

Although polio is nearly eradicated today, vaccines will continue even after it is completely wiped out to prevent a resurgence. The study in the Journal of Virology says the new method for producing a polio vaccine will contribute to a “polio-free world.”

“Our new method of creating the vaccine has been proven to work in lab conditions and on top of that we’ve proved it’s actually more stable than existing vaccines,” study co-leader and molecular virology professor David Rowlands said in the university statement.

Before the new vaccines can be used on humans, they will be researched using rats and mice, the university said.

“After that we need to find a way to manufacture them cost effectively on a large scale,” study co-leader Nicola Stonehouse added.

Source: Rowlands DJ, Adeyemi OO, Nicol C and Stonehouse NJ. Increasing Type 1 Poliovirus Capsid Stability by Thermal Selection. Journal of Virology. 2017.

See also:

Genital Herpes Vaccine Is on the Way

How Safe Is the Flu Vaccine?