First Human Tests of Hepatitis C Vaccine Begin
Researchers optimistic, but know there are many steps to go
MONDAY, Nov. 17, 2003 (HealthDayNews) -- Researchers are taking a careful first step toward a vaccine for hepatitis C, the liver-damaging virus that infects an estimated 2.7 million Americans and kills an estimated 8,000 to 10,000 of them each year.
An experimental vaccine developed by Chiron Corp. is being injected into 45 healthy volunteers, whose reactions will be monitored for a year, says Dr. Robert B. Belshe, director of the Center for Vaccine Development at Saint Louis University School of Medicine in St. Louis, where the experiment is being done.
The hope is this first trial, which focuses on the vaccine's safety and its ability to arouse the body's immune defenses, will lead to a product that can be used to protect people at high risk of being infected by the virus, which can be spread by sexual contact but mostly is transmitted by contaminated blood, Belshe says.
The road ahead is a long one, he warns, but at the same time he and other researchers are encouraged by the fact that any candidate vaccine is available.
The Saint Louis facility is one of the vaccine units funded by the National Institutes of Health, which participated in development of the vaccine. One reason why it was chosen for the trial is that "we have several people here who are experts on hepatitis viruses."
One of those experts is Dr. Adrian M. Di Bisceglie, chief of hepatology. The hepatitis C virus is a difficult target because "it mutates a lot and also because it is not a strong stimulator of the body's immune system," he says.
"Only now, 15 years after the hepatitis C virus was identified, do we have vaccines that we hope can be effective," Di Bisceglie says.
The vaccine uses bioengineered versions of proteins on the surface of the virus. It is designed to attract antibodies, defensive molecules produced by the immune system, and also to stimulate attack by immune system cells.
Blood samples will be taken periodically from the volunteers getting the vaccine to test for antibody and immune cell levels, Belshe says. If those responses are satisfactory, the next step will be a larger study, involving several hundred healthy volunteers, to get broader measures of safety and immune system response. A trial of the vaccine's effectiveness in protecting against hepatitis C infection would begin only if that study succeeds, he says.
Candidates for the effectiveness trial would be persons at high risk of hepatitis C infection, such as health-care workers and drug users who might share infected needles, Belshe says. Changes in the vaccine are expected before such a trial would begin.
"This vaccine is not expected to be the final vaccine," Belshe says. "But it is an important step along the way."
He hopes the hepatitis C vaccine program will follow the path of an earlier program that produced an effective vaccine against the hepatitis B virus. "That program also started with safety tests on healthy individuals, then moved to trials with people at high risk. "The vaccine was so effective and so safe that it now is used routinely," Belshe says.
"This is really the first candidate for a hepatitis C vaccine for humans in the United States," says Di Bisceglie. "We have many steps to go before we have a successful vaccine."