A phase I clinical trial for a new hepatitis C vaccine that has shown to be safe in humans shows promise in ongoing public health efforts to control the disease, especially for people who can’t afford treatment.

The first clinical trial of a hepatitis C vaccine in humans has demonstrated safety and unprecedented immune responses, according to research published this week in Science Translational Medicine.

B-cells produce antibodies that go after specific invaders. With the hepatitis C virus constantly changing (much like HIV) and having multiple genotypes, it is challenging for scientists to get B-cells to work effectively in a hepatitis C vaccine.

Using “helper” T-cells instead of B-cells that target specific intruders, the new vaccine provokes the immune system to go after the virus with its own defenses. About 15 to 25 percent of people who become infected with hepatitis C clear the virus spontaneously, according to the U.S. Centers for Disease Control and Prevention (CDC). Researchers have known that a powerful T-cell response plays a role in the body’s ability to do so.

The researchers used chimpanzee viruses as vaccine vectors in the trial. “The size and breadth of the immune responses seen in the healthy volunteers are unprecedented in magnitude for a hepatitis C vaccine,” lead researcher Ellie Barnes, of the Nuffield Department of Medicine at Oxford University, said in a press statement.

The next step in Barnes’ research is conducting larger, phase II clinical trials of the vaccine in San Francisco and Baltimore. The trials are currently underway among injection drug users.

“A range of different T-cells are produced targeting different parts of the hepatitis C virus,” Barnes said. “But we won’t know if it really works — if it is able to prevent hepatitis C infection — until we have the results of the efficacy studies in the U.S.”

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Dr. Jorge Herrera, a professor of medicine at University of South Alabama and a member of the American College of Gastroenterology, told Healthline that the T-cell approach in Barnes’ vaccine is what makes it exciting.

“B-cells have been shown not to work well with hepatitis C,” Herrera said. “But this is very preliminary with only 10 human volunteers, and it only showed that it can stimulate T-cell response, not prevent infection. And that is the next step. And is it going to work for all genotypes?“I think any positive movement toward a vaccine is very exciting,” Herrera said. “But we’re far from having a party to celebrate.”

Herrera has seen a large spike of hepatitis B cases in his practice. He believes the number of new infections is actually higher than reported. In a post-HIV scare era, groups at risk for hepatitis C, whether it be through sex or injection drug use, have thrown caution out the window, Herrera said. Although HIV is still a concern, Herrera said its widespread acceptance as a manageable disease has left a new era of Americans devoid of the fears associated with spreading infectious diseases

About 3 million people in America have hepatitis C, most of them baby boomers, according to the CDC. Many people contracted the disease long before scientists first identified it in 1989. Hepatitis C is primarily spread by blood-to-blood contact. This can occur when sharing needles during injection drug use as well as sharing straws or rolled bills when snorting drugs.

Other people contracted the disease from blood transfusions or organ transplants. Sterilization techniques in the United States pre-HIV weren’t as strong as they are now.

Hepatitis C continues to spread across the United States, primarily by the sharing of needles. Outbreaks of hepatitis C have been reported in recent years among young adults. They become addicted to painkillers as children and progress to injecting heroin, according to addiction experts.

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Hepatitis C is rarely spread sexually, except among men who have sex with men, and particularly among men who are also infected with HIV. However, it is possible for the virus to be transmitted even during heterosexual sex. Condoms are advised for protection against the disease.

Hepatitis C very slowly destroys the liver. People can be infected with hepatitis C for decades and not exhibit symptoms.

The issue of hepatitis C infection has been thrust into the national spotlight in the past couple of years. Just as drug manufacturers announced new medications that revolutionized treatment of hepatitis C with high cure rates and relatively few side effects, the CDC also called for every baby boomer to get tested for the disease.

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The treatments are expensive, costing more than $1,000 per pill for a once-daily, 12-week regimen. Given that much of the infected population relies on the public health care system for treatment, governments are scrambling for a cheaper solution to an emerging health crisis, particularly in developing countries.

According to the CDC, in 2012 only 1,778 cases of acute hepatitis C infection were reported in the United States, but the actual number is likely closer to 22,000 when adjusting for asymptomatic infections and underreporting.