The multiple formulation is necessary, according to Dr. Kenneth E. Sands, a research fellow at the Medical School and associate director of hospital epidemiology at Beth Israel Hospital, because of the ability of the influenza virus to change its appearance on a yearly basis by mutations.

Each year the CDC coordinates the effort to customize the vaccine for the expected strain or strains. In order to be protected from new strains of the virus, patients must get immunized every year.

Most hospitals and clinics hope to meet the high demand this year by increasing supplies. "We got 1,000 extra doses [of the flu vaccine] from the state health department at the beginning of the season and we do not anticipate running out," said Jane P. Taylor, director of public health nurses at Cambridge Hospital.

According to UHS's Rosenthal, however, the demand for the vaccine still consistently exceeds the supply. Because of the shortage, he said, UHS has been forced to put people on waiting lists.

Marta R. Weiss '96 was told that UHS had run out of the vaccine and that she would not be able to get vaccinated by the health services until the middle of November at the earliest. She was referred to Cambridge Hospital, where vaccinations will be available this week.

But not all young adults are enthusiastic about the shot in the arm.

"We've all had exams for the past few weeks, so we haven't had a weekend to be sick in bed," says Elizabeth M. Doherty '96. "I'll probably talk to some people and see what they advise, but I'm not stressing out about it."