Economic booms and improved transportation may come with a costly downside: increased transmission of viral diseases. Adda studied 25 years of weekly disease surveillance reports from across France, focusing on influenza, gastroenteritis, and chickenpox. He found that rail-worker strikes, which diminished travel, limited disease transmission, whereas the expansion of high-speed rail to new regions promoted disease spread. The estimated cost of this increased health burden was of the same magnitude as the benefit of improved travel. In times of economic prosperity, travel increased, driving up disease transmission. The impacts of holiday school closures suggest that, although closing schools during outbreaks could limit disease spread, this is not cost-effective in the light of lost learning and subsequent earning.
