Florida at risk: maritime connectivity during the COVID-19 pandemic

The maritime transportation network is a global system connected to most major cities. This network is relatively unexamined as a viral transmission route. An essential step in understanding the risk of maritime transmission is characterizing linkages between seaports. Records of ship arrivals in Florida were obtained for the first half of 2020, during the initial wave of the COVID-19 pandemic. Over 45,000 individual vessel calls to 17 Florida ports were recorded, including over 9,600 large ships capable of long-distance voyages. The prior port calls of all vessels were back-traced up to 2 months before they arrived in Florida. We identified 19,579 prior calls to countries on 6 continents and many island nations and territories. The most common (66%) previous port regions were in the Americas and the Caribbean, western Europe (8.5%), and eastern Asia (5.0%). Cargo class vessels had the largest number and most interconnected set of prior port visits compared to large Tanker, Passenger, and Personal craft. The history of incoming vessels varied between Florida ports, with some receiving a majority of vessels from U.S. prior ports, but most receiving a majority with non-US priors. Some implications of these findings for vessel tracking and the development of protection measures at ports are discussed.