Most of B.C.'s swine flu vaccine isn't lasting the length of time it was supposed to. (CBC)

The B.C. government hopes to recover at least part of the $20-million cost of swine flu vaccine it has to dump because the serum is unexpectedly spoiling far in advance of its best-before date.

The province is stuck with about 2.5 million doses of the vaccine, which were supposed to be good for 18 months, but have turned out to have only a six-month shelf life.

B.C. is among several health jurisdictions across the country left with the unusable medicine, and has joined other provinces in talks with manufacturer GlaxoSmithKline about recovering some of the cost.

"We're working … to see what we can do to find out if there is any kind of recovery," said B.C. Health Living Minister Ida Chong Wednesday.

"No one wants to see unused vaccines discarded in this way. Certainly no-one would have expected this, but it was a very novel virus."

The vaccine with a booster, or adjuvant, was expected to last through any new outbreak of swine flu, or H1N1, in the fall and early winter of 2010.

Health Canada raised alarm

Health Canada announced earlier in April that the adjuvanted vaccine was unexpectedly spoiling early.

The un-adjuvanted vaccine — intended for use by pregnant women and people who are immune-compromised — is lasting longer but it's not yet known if it will remain usable for the full 18 months.

B.C. ordered only 34,000 doses of the un-adjuvanted vaccine.

B.C.'s chief medical health officer, Dr. Perry Kendall, recommends people take advantage of the availability.

"If someone is worried, hasn't been vaccinated, is in a high-risk group, or newly pregnant, I'd suggest they take an opportunity to get the vaccine while we know we have ample supplies this month or next month," Kendall said.

About 40 per cent of British Columbians opted to get the swine flu shots after the government ordered 4.3 million doses, enough for every person in the province.

"It was important that we ordered enough vaccine for all British Columbians, which is what we did," said Chong.

B.C. had 1,059 confirmed cases of swine flu between April 2009 and February 2010, and 55 deaths were reported.

With files from the CBC's Jeff Davies and Heather Robinson