The most relevant study, though, was
a 2011 modeling of how a hypothetical influenza epidemic would spread throughout New York City, specifically focusing on the role the subway would play. The model found only four to five percent of transmissions would occur on the subway. Instead, most infections would occur within households (30 percent), at school (24.5 percent), and in other community settings (32.2 percent), such as entertainment districts, community meetings, bars, restaurants, etc. Ironically, these results are the exact opposite of the 2005 survey cited above where people believed home was safest and public transit was riskiest. This model’s findings suggest “interventions targeted at subway riders would be relatively ineffective in containing the epidemic.”
Therefore, riding public transportation in and of itself is probably not where people get sick. It is all the places riding transit enables them to go. If you use public transit, you’re likely using it to go to a big office building with one set of doors or elevators for hundreds or even thousands of people. You’re likely going to coffee shops and restaurants and standing on street corners huddled next to lots of other people.