CoPR is valid until medical or passport expires - whichever comes first. This means you have to land before this date (it will be printed on your CoPR) I would contact CIC if your medicals are expiring soon.
Thanks for the valuable information. But I have several more questions.
I did my first medical on 01AUG2015.
On 13MAY2016 I received an email request for a medical reassessment. The email header was like this
"This is in reference to your visa application for Canada.
The results of initial medical examinations for yourself has expired. In order to provide your application with an updated validity we require following additional medical examination(s) for yourself:
Chest Xray (in DICOM / JPEG format) with report (in PDF)
Completed MEDICAL REPORT CHEST X-RAY REQUISITION AND REPORT form (Page 5 and 6 of IMM5419) (in PDF)
Duly completed Re-assessment Form (Attached herewith)"
So I had my x-ray done again on 15May2016. Note that this was just the chest X-ray and not the whole medical like in the first time.
So now, will the validity of my medical be one year counting form my first medial or form the date of my reassesment (15May2016)
I also don't understand, that since it has not been one year yet, how can CIC say "The results of initial medical examinations for yourself has expired" ? Or is it that the x-ray only has a 6 month validity.
I understand that CoPR is valid for 6 months (or 6 months after DM).