Extra vaccine for the H1N1 virus has been exported out of Canada to other countries because producers are making more vaccine than can be stored in bottles, officials say.

Canada's chief public health officer, Dr. David Butler-Jones, said Tuesday that GlaxoSmithKline has shipped bulk quantities of the antigen, the main ingredient of the vaccine, out of the country.

Speaking in British Columbia, Butler-Jones said the bulk exports were allowed because Canada had enough for its purposes.

Butler-Jones said this move doesn't slow down the country's swine flu vaccination campaign.

The Public Health Agency of Canada said the vaccine antigen was sent to other manufacturing facilities in Europe and other countries several months ago.

But the extra vaccine would not have made a difference, officials say, because of a bottling issue. The vaccine producer can make more bulk vaccine than it can put into bottles.

In June, officials considered getting the excess bottled somewhere else but decided against it.

At the time, they thought it might add a million or so doses a week, but they didn't think they could get it into people's arms any faster.

Thousands of people across Canada have lined up for hours to get vaccinated and many clinics have had to close, overwhelmed by the demand.

This week, provinces received a fraction of the H1N1 vaccine compared with previous weeks. Next week, it's expected that vaccine shipments will return to high levels.

Butler-Jones added that just a week into the campaign, 10 to 20 per cent of people in many communities have been vaccinated — more than in any other country in the world.

For the next pandemic, there are plans to increase capacity so Canada's entire supply can be bottled in a single month.

With files from The Canadian Press