You are entitled to sick leave protection if you have worked for the same employer for at least three consecutive months.
You are protected for any absence less than 17 weeks.
Your seniority and your pension, health and disability benefits will continue to accrue during your sick leave. Employers must make their normal share of contributions and pay them within a reasonable time, but only if employees also continue to make their required contributions. Failure to pay may affect your benefit plans (check with your employer to find out how), but would not affect your status with your employer.
You must provide a medical certificate if your employer requests one—in writing—within 15 days of your return to work.
See Pamphlet #7 - Sick Leave and Work-related Illness and Injury Leave for more details.