What is the likelihood of infection on an airplane or bus?
The likelihood of transmission is high. Especially if there are symptomatic individuals on board. The NEJM published a report on SARS-CoV demonstrating which individuals including the crew was infected (10.1056/NEJMoa031349). While the data can not be directly translated into infection with the SARS-CoV-2 it is more than likely that transmission can occurs on public transportation since SARS-CoV-2 is more contagious