B.C. will have nearly one-third less vaccine than it expected to have next week due to demand that the manufacturer cannot keep up with. (CBC)

Less than a week into B.C.'s swine flu vaccination program, health officials are grappling with a major shortage of the vaccine.

The province will receive 500,000 fewer doses than it expected to have on hand by Nov. 6, according to provincial health officer Dr. Perry Kendall.

"We're getting it in smaller amounts than we thought, which means we can put it into fewer arms than we would originally like to do," Kendall told CBC News on Thursday.

B.C. was supposed to receive 1,350,000 doses by the end of next week, but the federal government has now cut that total shipment to 850,000, according to the B.C. Centre for Disease Control.

Kendall said the manufacturer has been unable to meet production targets.

That will be unwelcome news for tens of thousands of British Columbians who are in priority groups for vaccination and had been counting on earlier announcements that much larger amounts of vaccine would be available starting Nov. 2.

"The fact that I have to wait is a little frustrating in some ways, because I'm very susceptible," said Erin Lowe, 27, who is asthmatic and had counted on getting inoculated at a clinic in Vancouver's Yaletown on Thursday evening.

The clinic has run out of vaccine.

Clinics around the province have been dealing with high demand since the vaccine became available this week, with typically several hundred people lining up for hours.