Two persons associated with Howard University Medical Center died of hepatitis last month, prompting an investigation by authorities who noted the long odds against such an occurrence.

A registered nurse who worked at the medical center died Dec. 3 of the liver inflammation and a medical student at Howard died 27 days later. Both were in their early 20s. Officials declined to release their names.

Dr. Vincent Roux, medical director of the Howard University Hospital, said the nurse died of a form of hepatitis known as Type B. He said the form contracted by the student is not yet known but is believed also to be Type B. Type B hepatitis is fatal in less than one case in 100.

Although unusual, the deaths appear not to pose any public health hazard in the District, according to Dr. Martin E. Levy, chief of the city's communicable disease control division.

He said the methods by which the Type B virus disease is transmitted make it unlikely that it could be widely spread.

Type B hepatitis was once believed transmitted only by transfusion of contanimated blood or injection with a contaminated needle. More recently it has been found that it also can be transmitted through intimate oral or sexual contact.

Taking account of the long odds against death from Type B, the two fatalities in one month seem unusual and "that's why we're investigating," said Dr. Roux. He said city and federal authorities are expected to join in the inquiry.

"Quite frankly," Dr. Roux said last night, "we haven't been able" to find an explanation for the deaths. He said no connection has been found between the two victims. "These people didn't even know each other, he said.

While the last hepatitis death among staff members of the medical center was about 10 years ago, the occurrence of two deaths in one month is probably going to wind up being coincidence," Dr. Roux said.

The nurse, who was first hospitalized at Howard, died at Georgetown University Hospital where she was transferred to undergo as a "last resort," a blood-cleansing treatment being developed there, Roux said. Hepatitis for which there is no real treatment impairs ability of the liver to remove from the blood the toxic byproducts of bodily functions. The medical student died in a hostpial in Atlanta where he had gone for the Christmas vacation.