IMHO, this issue will become a political issue rather than a health issue. Political because this may be seen as discriminatory to certain sector. Also, banning direct flights while allowing transit flights doesn’t make any sense at all. Considering that there is a high risk of false negative result from a PCR test (
https://medical.mit.edu/covid-19-updates/2020/07/when-should-i-be-tested). Consider this: Canada bans direct flight from country A. So travellers from country A will transit to country B. Even with just one infected from country A gets into that flight, the whole plane gets compromised, therefore compromising country B as well. So, the more pragmatic approach should be to ban all passenger filghts, regardless of origin in order to be politically correct.
The infection report we read or hear from the news every day does not guarantee accuracy. Each country’s report is limited to that country’s ability to test its residents. Some countries have the resources and the logistics to test more while some simply don’t. All data modelling doesn’t show data from population density and population movement. For example, Durham region in Ontario is a hotspot area despite it being a residential area. The reason is because Durham residents work outside of the region, thereby the risk of infection is high. People wearing masks did not really deter the viral infection. And anybody who have been here knows how many stay at home orders we’ve had. Did it stop the pandemic? Nope.
Viruses mutate, that’s true. But different places have different mutations. You cannot have the same mutation in two different places unless you import that mutation.
Outbreak starts with just one person, patient zero. When that person infects one or two, exponentiate that and you would have a predictive model. Now factor in one or two new infections coming in (if I’m not mistaken the data on incoming passengers who tested positive since January was around 3k or 1.4% of the total incoming passengers), and you have a potential outbreak.
If the whole world meticulously isolated even for just two continuous weeks, we wouldn’t have this pandemic now. But then, we cannot afford the whole world to stop even for a day...