An experimental vaccine for hepatitis C has shown promise in preliminary human safety trials, according to researchers, and may pave the way to a more affordable means of fighting the virus.

In a paper published Wednesday in the journal Science Translational Medicine, authors wrote that 15 people in Britain were given a “prime and boost” course of the experimental vaccine.

Researchers said the shots stimulated a protective response from the body’s T cells — white blood cells that are critical to battling pathogens.

Although the vaccine caused headaches, feverishness and fatigue in some subjects, researchers said those adverse effects disappeared within two days. Overall, they said the vaccine proved to be “safe and well tolerated.”

A larger Phase II trial will now be performed on more than 350 test subjects at the University of California, San Francisco, and Johns Hopkins Bloomberg School of Public Health, according to the National Institutes of Health.

“We won’t really know if it works — if it is able to prevent hepatitis C infection — until we have the results of the efficacy studies in the USA,” said Eleanor Barnes, an immunology professor at Oxford University and the paper’s senior author.

Hepatitis C is believed to affect 180 million people worldwide, and is spread through contact with infected blood. It often is associated with intravenous drug use and can lurk in the body for years before it is detected. It is a leading cause of liver cirrhosis and can lead to liver failure and liver cancer.