Take a guess: Between a low-density mostly suburban metropolis in the US, or New York City, in which do you think you’d be more vulnerable dying from a flu caught on transit?
The answer seems so obvious – how could it not be New York with one of the largest and most congested transit systems in the world? But when looking at the rate of transmission, that’s not exactly so, according to this chart:
I know, not user friendly. Apparently though, New York has a very low flu rate compared to places like Duluth. That’s not no flu or less flu, just not as much as you’d expect given its very high transit usage.
The conclusion of the authors:
We find no evidence of a positive relationship between city-level transit ridership and influenza/pneumonia mortality rates, suggesting that population level rates of transit use are not a singularly important factor in the transmission of influenza.
A New Yorker reader on the subway is less likely to catch the flu than a bus rider in Duluth.
William Demopoulos, who passed along the study, provides some perspective.
- I never judge based on one study.
- But an inverse correlation with significance says much more than no evidence.
- It suggests there’s a mystery.
- Transit is a vector for disease in other ways. For example, it probably allows inter-neighbourhood travel for those who are asymptomatic.
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It’s going to be critical for the revival of transit that people feel comfortable with the assumed risk. At this point it would be wise to withhold too much judgment on that degree of risk until we see what actually happens.
Sam Schwartz released a COVID paper two months ago with a lot of the same research and results. It’s not so mysterious when one considers the demographic and socioeconomic make up of average transit riders in NYC as opposed to most other US cities which have far higher proportions of captive riders (those with no choice) who tend to be poorer and older. These people are going to die of the flu at higher rates no matter how they get to work. In this case, it is more likely that in most of the US, transit useage and flu mortality rates are not directly related but are instead joint conditions (or symptoms) of relative poverty.