A handout photo shows a technician preparing chicken eggs for vaccine production at a laboratory in Dresden. (Reuters)

Some Ontario residents at high risk of complications from swine flu are unable to get the vaccine against it because they are allergic to eggs.

Eggs are used as incubators for the H1N1 vaccine, so Canada's chief medical officer, Dr. David Butler-Jones, has advised those with egg allergies to get vaccinated under the supervision of their allergists.

People with such allergies often have asthma or other respiratory difficulties that put them at higher risk of complications if they get the flu.

However, so far the vaccine is not available to Ontario allergists.

"It's been frustrating," said Ottawa allergist Dr. Seema Khan. "We've made many phone calls trying to figure out when we can get the vaccine."

Allergists can determine what precautions must be taken for each patient depending on medical history. They can use methods to help desensitize some patients to the vaccine if necessary. They are also trained to recognize and treat any dangerous adverse reactions that might occur.

Private physicians have to fill out forms to get authorization to vaccinate, but the province of Ontario hasn't sent the forms yet, Khan said.

That means Ottawa resident Elizabeth McCarten can't get her 17-year-old daughter Isabel, who has asthma and is allergic to eggs, vaccinated. She is upset at provincial health authorities for the delay.

"They don't seem to appreciate that the patients who are involved are the ones who are at risk of severe complications and are the ones who could end up on ventilators," she said.

McCarten has just returned to Canada with her family after 16 years in Washington, D.C. Her daughter's allergist in Washington is already administering the H1N1 vaccine. She said she's hoping the vaccine will be available to her daughter in Canada soon, but if it isn't, she'll consider taking Isabel back to Washington to get the shot.

There are ways to produce vaccines without using eggs.

But on Tuesday, Dr. Thomas Frieden, director of the U.S. Centers for Disease Control and Prevention in Atlanta, said these non-egg based approaches for creating flu vaccines are still considered experimental, and he's unaware of any countries using these techniques.