Public health officials in Ontario are undertaking rapid deployment of the new H1N1 vaccine to all corners of the province, as part of phase two of this year's immunization program.

Ontario is the most densely populated province in Canada and is one of the largest geographically. Ontario estimates that the initial shipment of 722,000 doses of adjuvanted vaccine will reach all regions across the province within a few days now that the federal government is authorizing the vaccine for public use.

The province's 36 public health units are responsible for the delivery of the H1N1 immunization program. Ontario is recommending the following groups first for immunization:

• People under 65 with chronic conditions;
• Pregnant women;
• Healthy children 6 months to under 5 years of age;
• Persons residing in remote and isolated settings or communities;
• Health care workers; and
• Household contacts and care providers of persons at high risk who cannot be immunized or may not respond to vaccines.

Because rates of H1N1 illness are rising in Ontario and many other parts of the country, it is uncertain when the unadjuvanted vaccine will be available and it takes up to 14 days to develop an adequate immune response. Ontario is recommending that:

• All pregnant women with pre-existing health conditions and healthy pregnant women in the second half of their pregnancy (more than 20 weeks) - should speak to their health care provider about receiving the adjuvanted vaccine. 

• Healthy pregnant women in the first half of their pregnancy are at less risk of complications from the flu, and should wait to receive the unadjuvanted vaccine, when it is available. 

Pregnant women who develop flu-like symptoms should contact their health care provider right away. Early treatment with antiviral medications may lessen the severity and length of illness which will reduce the risk of complications both for your and your baby.

Sequencing guidelines to administer the H1N1 vaccine are required because the vaccine will not be available at the same time for everyone and Ontario wants to target the first doses to people who will benefit the most.

Ontario will continue to receive enough vaccine to immunize all those who need and want it. The adjuvanted vaccine includes a substance that boosts an individual's immune system and increases their response to a vaccine. The adjuvant in Canada's H1N1 vaccine is made up of ingredients such as water, oil and vitamin E. Another potential benefit of using an adjuvant is that it may provide protection against the flu virus even if any slight change occurs in the virus strain. The use of an adjuvant also reduces the amount of vaccine that is needed and contributes to a "dose-sparing approach", which means that more vaccine is available.