TORONTO - Monday marks the start of H1N1 flu vaccination programs across most of Ontario for a high-risk priority group of people, and officials are urging all others to wait their turn.

The rollout comes days after the province's top medical official confirmed the second wave of the pandemic swine flu has arrived in Ontario, with 28 deaths and 31 people currently in hospital.

Ottawa approved the H1N1 vaccine on Wednesday, and 722,000 doses of the vaccine arrived at the province's 36 local health units on Friday. Ontario expects to receive a second shipment of vaccine some time this week.

The vaccine will be available to certain high-risk groups starting Monday, though vaccination programs differ from region to region.

Most regions have vaccination clinics for high-risk groups starting between Monday and Friday. Regions such as the city of Toronto and the Simcoe Muskoka district are launching clinics on a broader basis starting the following week.

"There will be enough vaccine for everyone who needs and wants it, but people will need to be patient and let the priority groups go to the front of the line to get immunized first," said Dr. Arlene King, Ontario's chief medical officer of health.

That priority group includes adults 65 and under with chronic health conditions, pregnant women, healthy children six months to under five years old, health-care workers and people in remote or isolated communities, King said.

The list also includes people who care for or come into contact with high-risk people who can't be immunized.

Vaccinations will continue throughout November and December. For specific times and locations residents are asked to contact their local public health unit.

"We would like to see everybody in the province immunized," King said.

But officials are realistic and have ordered enough vaccine for 75 per cent of the population, King said. Less than 50 per cent of the population usually gets immunized against the seasonal flu, she said.

"This is the largest immunization program we've mounted in the history of this province, in the history of this country, so I hope that that will result in higher immunization rates than we get with our seasonal flu campaign," King said.

People should get the H1N1 vaccination not only for themselves, but also for their community at large, said Dr. Vivek Goel, the president and CEO of the Ontario Agency for Health Protection and Promotion.

"This is an immunization that has really two benefits: one is for the individual in terms of providing them with a degree of protection, but it's also for everyone around them," he said.

King declared Friday that the second wave of swine flu had arrived in Ontario.

The number of deaths since April had risen over the past few weeks from 24 to 28, she said. The average age of people who have come down with swine flu (in lab confirmed cases) is 18, King said. The average age of hospitalization has been 28 and the average age of death -- though rare -- has been 55.

Anyone over the age of 10 will only need one dose of the vaccine for full immunity against the swine flu instead of two, as previously thought, King has said. Children under 10 will require two half doses, given at a minimum of 21 days apart.

People over 65 seem to have an immunity to the H1N1 virus and are being asked to get the seasonal flu shot only for now. As well, people who have had lab confirmed cases of H1N1 seem to be immune to getting it again, King said.