"J Infect Public Health" . "PMC" . "30878442" . . . "Geography, global pandemics & air travel: Faster, fuller, further & more frequent" . . . "10.1016/j.jiph.2019.02.020" . . "PMC7129534" . "Houghton, Frank" . "no-cc" . . . "2019-03-13"^^ . "30878442" . .