A steady stream of pregnant women, about 100 in the first hour, flowed in and out of the Nassau health department's building in Uniondale on Friday night to receive one of the still-rare H1N1 vaccine inoculations.

"This program was very well-organized," said Rosalinda Arroyo, 30, of Jericho , a pregnant woman who was grateful to receive one of the free shots. "This is what we need to see more of."

Pregnant women are at especially high risk of complications if they get swine flu. Much of the vaccine available now is the nasal spray not considered safe for pregnant women.

Helen Costalas, 27, of Merrick , said up until Friday night, she was unable to find the vaccine anywhere. "This is such a mix-up," Costalas said. "So many places don't have the vaccine for people who need it."

Mary Ellen Laurain, a spokeswoman for the county health department, said 6 percent of deaths attributed to swine flu nationally were of pregnant women. For that reason, the county earmarked the 800 doses it received for that group.

By the end of Friday evening, 260 women had been vaccinated. Laurain said officials would meet Monday to determine when and where the remaining dosages would be distributed.