I think with the case in Hong Kong, many factors helped slow the spread of the virus.
1. Previous extensive experience with SARS;
2. Top notch healthcare system;
3. Almost completely closed borders to China, albeit slowly;
4. Immediate and strong response from local residents to wash hands, wear masks, sanitize, avoid crowds, etc. So in doing that everyone was in the fight from the beginning. If anyone was infected themselves and they did not know it at the time, the fact that they were wearing masks helped minimize the spread to others. I am very aware of what the doctors and medical professionals are saying about masks and the shortage problem. While I agree everyone wearing masks is creating a shortage, I don’t agree that everyone wearing masks is not helping slow the spread. And I mean everyone, not just a small portion of society. I highly doubt the West will have everyone wearing masks because the message is very different from what is being said in the East. There’s a cultural aspect to this and the attitudes and response to this are just very different. In the East, not wearing masks is stigmatized. In the West, it’s the opposite.
Just a nugget of interesting info: our city had 3 infected people who arrived on a plane from China, all were wearing masks on the plane and went into voluntary isolation immediately upon arriving. No new cases ever resulted from those 3 initial cases. Then the cases coming from China just stopped due to border closures. And we had no new cases for a few weeks. Nada. This was a huge surprise because we have a large Chinese population here. We were expecting a lot more cases. Now we have over 30 cases, all of them coming from outside Asia: Iran, Italy, France, Las Vegas, Colorado, etc. Few, if any, were wearing masks on the plane nor self isolated upon arrival. These people went out in public doing regular life stuff after arriving. Now our health officials are scrambling to track down everyone that they might’ve infected, including those on public transit. My only point here is that the human/community response and cultural attitudes about this are so different. Coming from both an Eastern and Western cultural background, the difference is very stark.