For the 185 million people nationwide who face serious health risks during the flu season each year, a potential crisis developed last fall when the United States found itself facing a shortage of flu vaccinations.

The nation’s supply of the vaccine was severely constricted on Oct. 5 when British health officials suspended Chrion Corporation’s manufacturing license for three months. The Liverpool-based company is the world’s second largest flu vaccination producer and supplies about half of U.S. flu vaccinations.

In response, the Center for Disease Control (CDC) issued guidelines establishing priority groups who should receive the nation’s remaining vaccines.

They included children between six and 23 months, adults over 65 years old, all persons with chronic medical conditions, pregnant women, and health care workers.

The U.S. Department of Defense issued a memorandum on Oct. 13 stating that vaccinations would also be given to the “critical operational forces who are conducting the Global War on Terror.”

“All health providers and hospitals have been asked to focus on high-risk individuals.” said University Health Services (UHS) Director David S. Rosenthal ’59 at the time.

During the 2003-2004 school year, UHS gave between 11,000 and 12,000 flu shots, according to Rosenthal.

“This year, we expected a demand of 13,000 and ordered 14,000 flu vaccinations,” he said. “We didn’t get the 7,000 from Chiron.”

The other 7,000, ordered from Aventis, arrived on schedule.

Rosenthal said that UHS could not obtain more vaccinations because “the margin of profit in this type of business is very small.”

Only four companies worldwide produce flu vaccines.

CDC spokesman Curtis L. Allen said flu vaccine production, which may take at least six months, can be a tricky business because it requires predicting demand in advance each year.

“185 million doses should be given out a year,” he said. “In 2002, 95 million doses were produced, but companies only sold 83 million. At 10 dollars a dose, that’s over $100 million lost in revenue.”

Due to CDC regulations, UHS was required to sell a portion of vaccinations to the state; it donated additional units to the city of Cambridge.

Crista Martin, Harvard University Dining Services’ (HUDS) assistant director of marketing, said HUDS did its part by rotating available utensils every 20 minutes, supplying hand sanitizer to students, and posting signs reminding students to wash their hands.

“This is a cooperative effort,” said HUDS Executive Director Ted A. Mayer last October. “We don’t want people to get sick.”

Due to these efforts, Rosenthal said UHS did not experience a significant increase in flu patients this year.

In addition, this year was “a mild season” according to Allen. “Most of the lack of influenza can be attributed to that fact,” he said.

To prevent the possibility of such a vaccination shortage occurring again, the federal government is now subsidizing pharmaceutical companies to encourage them to begin vaccine production.

Rosenthal said that scientists were also looking to see if the time which it takes to make vaccines could be shortened.

—Staff writer Risheng Xu can be reached at xu4@fas.harvard.edu.