OTTAWA - Canadians who dread their annual flu shot may have to roll up their sleeves three times this fall.

People seeking protection will need two swine flu shots, in addition to their regular flu shot, health officials said Monday. Canada's chief public health officer, Dr. David Butler-Jones, says putting both the regular flu and swine flu vaccine into one needle would have delayed production.

"All the manufacturers internationally were well on the way with the production with their seasonal flu (vaccine). And so to substitute or add the H1 to it would have delayed the whole process," he said.

Butler-Jones said the two additional shots to protect against swine flu must be done a month apart.

A regular flu shot protects against one strain of influenza B and two of influenza A, including a human subtype that rather confusingly goes by the same name as the swine-flu virus - H1N1.

Despite the similarity in names, the regular flu shot doesn't offer any protection against the new swine-derived virus.

Canada has a long-standing contract with pharmaceutical giant GlaxoSmithKline to produce a new vaccine for swine flu when one is developed.

Butler-Jones said Canada has until the end of July to place its vaccine order. The swine flu shot is expected by the end of October, and vaccinations - which are voluntary - will follow over the next four to eight weeks.

Health Canada, which regulates vaccines, has said manufacturers will be required to submit immunogenicity data - results of clinical trials that show whether the vaccine elicits a sufficiently strong immune response. And vaccine manufacturers are being asked to submit plans for how they will conduct surveillance for adverse events once their vaccines are in wide use.

As of June 26, Canada had confirmed 7,775 cases of the H1N1 virus, most of them mild. Twenty-six people have died and another 496 have been sent to hospital.

Butler-Jones said there have been some pockets of increased severity, leaving health officials scratching their heads. The majority of cases are those under the age of 20, he added.

The Public Health Agency of Canada's website says the common flu sends about 20,000 Canadians to hospital each year. Between 4,000 and 8,000 Canadians die of influenza and its complications annually, depending on the severity of the season.