It depends very much on how secure and comprehensive your quarantine efforts are.According to the WHO, quarantine alone is not enough. You need to do mass testing so that you can find and break the chains of transmission.
Unfortunately, Canada does not have sufficient testing capacity to do this. Hopefully it's just the bureaucracy ramping up and we will have more testing capacity soon.
The WHO is only recommending massed testing because it does not expect many other countries to be able to mount as effective and comprehensive a lockdown as China did.
If you cannot keep everyone quarantined, mass testing allows you to strip out as many infected as possible for focused quarantine.
But reliance on mass testing is at best a second best solution, and potentially ineffective since we know from many case studies that infected could return negative results multiple times while infected.
I think the west’s decision to advice against massed generalised mask usage is a major mistake.
While masks along cannot guarantee you won’t catch the virus, it does reduce the risks of you catching in. But much more importantly, if everyone wears masks at all time’s out in public, the odds and instances of non-symptomatic infected passing on the infection is drastically reduced if they wear masks.
Wearing masks is actually a civic duty as it protects others from you much more than it protects you from others.
Widespread mask wearing is a cheap and effective way to help break the infection chain even if you cannot achieve full comprehensive nationwide quarantine (which not even China has managed to be frank).
Personally I think masks is the most effective low hanging fruit that any nation battling to contain COVID19 outbreaks could pick.
It’s not hard to enforce mandatory mask wearing as anyone with eyes could see if people are doing it or not.
The only thing stopping western governments from doing it is logistics because they don’t have enough masks for that. But that can be remedied very easily through direct resists to China and domestic production.
Disposable masks are hardly cutting edge tech that will be hard to put into production from scratch.
If you combine lockdowns with mandatory mask wearing while in public, I think you can get a good handle on the virus pretty quickly even without SK levels of massed testing.