On the London Underground, where there is an extremely high density of people crowded into each carriage, previous research has suggested a link between commuting and the likelihood of catching respiratory illnesses.
Dr Lara Gosce, at the Institute of Global Health, says her research (published in 2018)
showed people who used the Underground regularly were more likely to suffer flu-like symptoms.
"Particularly, it shows that boroughs served by fewer lines - where inhabitants are forced to change line one or more times when travelling on the Underground - have higher rates of influenza-like diseases, compared to well-served boroughs where passengers reach their destination by one direct trip," she said.
If you're travelling on a relatively empty train or bus, though, your risks would be different. How well vehicles are ventilated and how long you spend on them will also play a role.
And cleaning will be a factor too. Network Rail says it is continuing with its "business as usual" cleaning schedule but is making plans for extra, specialist cleans of stations and trains if necessary.
Dr Gosce says that "limiting the number of close contacts with potentially infected individuals and objects is important".
"In terms of travel, avoid peak hours if possible," she says, suggesting, where viable, passengers should choose routes involving only one means of transport.
Currently, the UK government is not telling people to avoid public transport. David Nabarro, a special adviser on coronavirus for the World Health Organization (WHO), told the BBC that although public transport was an important thing to look at, the evidence suggested that the kind of "fleeting contacts" people have when travelling together didn't so far seem to be the "most important source of transmission".