A Montgomery County vaccination clinic ran out of the injectable form of the H1N1 vaccine Wednesday at the Piccard Drive Health Center in Rockville.

The county health department announced it had a limited amount of the injectable form of the vaccine reserved for priority groups. Spokeswoman Mary Anderson said the clinic had only 200 doses of injectable vaccine, which was being reserved for pregnant women, children ages 6 months to 2 years and children and older adults with chronic illnesses.

Those waiting in line who could not receive the nasal spray were turned away after the injectable form ran out.

"[The clinic] was advertised to people in the target groups," Anderson said. "We have not been able to turn people away," though they encouraged low-risk residents to wait for future clinics.

County residents waited in long lines to receive the free vaccine. Anderson said at least one family began waiting at midnight and that dozens were in line by 6:30 a.m. The clinic stopped letting people line up at noon. At 1 p.m. there were still residents waiting and Anderson estimated about 1,500 people would have come through the clinic by the end of the day.

The shortage comes at a time when supplies of the vaccine are slowing across the country. Maryland had only received about half the amount of vaccine it had originally anticipated for this month.

A spokesman for the Maryland Department of Health and Mental Hygiene said delivery has slowed because of inspections.

"The FDA inspections have been very tough," said spokesman David Paulson. "Nobody wants to send any vaccine to any location that isn't as good as it can possibly be."

At a clinic last week in Silver Spring, health officials had told those not in the priority groups to wait for future clinics.