It was a disease they never saw coming. They had gone to Exeter Hospital seeking treatment for other ailments, and wound up exposed to the hepatitis virus, allegedly by a technician now under federal indictment.

On this August evening, the patients had the opportunity, promotional materials from an advocacy group promised, to learn about “new wonder drugs” with a “75 percent cure rate in clinical trials” from a Harvard Medical School instructor and liver disease researcher at Massachusetts General Hospital.

As he took the microphone, Dr. Raymond T. Chung offered an authoritative message of deliverance: “We want to get about the business of helping these folks undo what’s been done unto them.”

But the drug combination that Chung hoped would undo hepatitis C’s damage had not been approved by the Food and Drug Administration, remained in clinical trials, and would not be approved for study by the committee that oversees Mass. General research until a month after Chung’s presentation.

Ethicists said in interviews that Chung’s comments appear to have breached ethics principles by potentially leaving his audience with outsize hope for drugs undergoing testing. Doing so, they said, was particularly striking at a moment when patients felt violated and vulnerable.

“I believe Dr. Chung is very well meaning, and it is possible that his study drug may be better than what is currently available,” said Dr. Brian O’Sullivan, director of the University of Massachusetts Medical School’s Bioethics Core. “But to sell it as such to a scared, desperate audience is not appropriate. He is misconstruing a promising but as yet unproven drug as a therapeutic alternative.”

Chung and hospital officials disputed the ethicists’ conclusions. In an interview, Chung said his comments reflected the promise of the drugs and his desire to make them available to patients who could benefit most — a presentation that, he said, conformed to ethical standards for clinical trials.

“We were very clear that this was a study,” Chung said in the telephone interview, “that this is a protocol and that patients would have to go through the next steps of private discussion and informed consent with a discussion of risks and benefits.

“That’s an absolute foundation of what we do with our clinical trials.”

For Jean Burke’s husband, who is among the infected and attended an earlier presentation by Chung in the summer, the doctor proved persuasive — so much so that her husband met privately with him and plans to enroll in the study, should it go forward.

“His reputation is nationally known. He’s a really excellent doctor and has been doing research on this for years,” said Burke, who said she and her husband understood Chung was talking about a drug trial. “He’s assured us that it’s probably going to be really successful.”

* * *

Human drug trials remain among the thorniest areas in medical ethics, poised between the need for scientific advancement and the mandate to protect patients. The revelation in the 1970s of the Tuskegee syphilis experiments, in which researchers deliberately withheld treatment from African-American men, spurred Congress to pass laws governing scientific trials.

A key area of oversight is recruitment, which can pose a hurdle for researchers. While patients stricken with life-ending illnesses, desperate for anything, sometimes seek out researchers and their trials, patients suffering diseases that do not pose an imminent threat may be less willing to submit to experimental interventions.

“Most people don’t want to be in research,” said George Annas, an ethics specialist at Boston University School of Public Health. “They want to be in treatment.”

Institutional review boards, composed of at least five members designated by the research institution, are charged with ensuring that researchers do not intentionally mislead patients about side effects and risks of an experimental drug. The review boards must also be on the lookout for well-meaning scientists who possess an exaggerated belief in their research and convey that to subjects — a phenomenon known as the therapeutic misconception.

“Researchers hope their drugs do well,” said Dr. Michael Grodin, a bioethicist at BU’s public health school. “There’s a bias on the investigator’s part. And that’s exactly why we want patients to know it’s research and not therapy.”

* * *