The Student Health Center was forced to abruptly end a walk-in flu shot vaccine clinic on Wednesday when its vaccine supply ran out.

This shortfall came after delays in the shipment of the vaccine last month caused the university to cancel other flu shot clinics. Vaccine distributors said that shipments were being postponed pending quality-control testing by the vaccine’s principal manufacturer, Chiron Corporation.

The SHC had approximately 270 doses of vaccine available at the start of Wednesday’s clinic, said SHC Director James Marsh. He said that those doses were exhausted in a matter of hours.

“We’re really at the mercy of the vaccine suppliers, who are at the mercy of Chiron,” said James Welsh, assistant vice president for student health. The student body will be notified immediately via e-mail if more vaccines become available, he added.

Wednesday’s clinic was the third that the SHC has held since procuring a supply of the vaccine several weeks ago. More clinics are scheduled this month, but Marsh said that they will likely be canceled if the necessary supply is not received.

The SHC ordered the vaccine from two separate manufacturers, Sanofi-Aventis, Inc., and Chiron, hoping to prevent a shortage. The center received its full order of 770 doses from Sanofi-Aventis, but only 740 of 2,230 doses it ordered from Chiron. The center received its last shipment nearly two weeks ago.

“We’re still hopeful that we’ll get additional vaccine,” Marsh said. “We’re in contact with [the distributors] really almost every day.”

There are currently only three manufacturers of the flu vaccine that are licensed in the United States. Due to high demand and low supply, distribution clinics are supplied according to priority as doses of the vaccine become available.

Chiron released 1,000,000 doses earlier this week, but Marsh said that the SHC is not on the list to receive any of those doses.

“We do know that . other clinics in the area are having the same problem,” he added.

More than 71 million doses of flu vaccine have been distributed in the United States, according to a press release posted on the Center for Disease Control and Prevention’s Web site.

While the flu shot is the most common means of vaccination, a nasal spray form of the vaccine exists as one alternative. The spray must be kept frozen until immediately prior to being administered, and thus “doesn’t lend itself to a large scale, walk-in distribution clinic,” Marsh said.

The SHC hopes to receive enough supply of the flu shot to hold more clinics before students depart for the semester break, he said.

Welsh noted that in the meantime, the center maintains an adequate supply for students at high-risk for contracting the flu – those with asthma and other chronic illnesses.

“We’re keeping our fingers crossed,” Welsh said.