As an international student in Australia, you and your dependents are required to have Overseas Student Health Cover (OSHC) for the entire duration of your study in Australia. This insurance will cover for visits to the doctor, some hospital treatment, ambulance cover and limited pharmaceuticals (medicines).
You can find more information on the Department of Health website. Remember, the Department of Immigration and Citizenship requires overseas students to maintain OSHC for the duration of time they are in Australia. https://immi.homeaffairs.gov.au/visas/getting-a-visa/visa-listing/student-500/length-of-stay.