If a foreign national you're bringing to Canada is required to undergo a medical examination or treatment, you as the commercial transporter are responsible for arranging it. You're not responsible if the person already had a valid visa at the time of examination or if their health issue wasn't caused by the transportation.
(1)263 (1) A commercial transporter must arrange for the medical examination of a foreign national who is required to submit to one under paragraph 16(2)(b) of the Act and for any medical examination, surveillance or treatment that is imposed under section 32.
(3)(3) For the purposes of paragraph 148(1)(g) of the Act, any medical costs incurred with respect to the foreign national are prescribed costs and are to be calculated on the basis of the applicable provincial health insurance system.