This is a valid point - air travel certainly can lead to the rapid global spread of infectious disease - but there's a counterpoint, for example the smallpox er

This is a valid point - air travel certainly can lead to the rapid global spread of infectious disease - but there's a counterpoint, for example the smallpox eradication program would likely have been impossible without the use of air travel as well. Here's a great overview of that campaign by its main director: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3720050/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3720050/ Lessons from the eradication of smallpox: an interview with D. A. Henderson (2013)