TORONTO - Ontario's top medical health official says the province is ready to begin the next phase of H1N1 vaccinations by opening flu-shot clinics to school children 13 and under.

Dr. Arlene King says beginning next week, the children can get their shots at doctors' offices and public health clinics.

Adults 65 and older who have underlying health conditions such as diabetes, cardiac disease or cancer can also start getting shots next week at their doctors' offices.

King says immunizing school-age children will help to reduce transmission of the disease.

Officials estimate there are about 2.25 million elementary school children and seniors with underlying chronic conditions, and it will take several weeks to immunize everyone in these two target groups.