Adapting Quarantine as a Public Health Measure to Scenarios Where Community Transmission Is Ongoing on Both Sides of a Border

Speaker: Jeffrey Townsend, Professor of Biostatistics, Ecology, and Evolutionary Biology at the Yale School of Public Health

Abstract: There is a longstanding gap in the science of public health: when there is already community transmission at a destination, how much travel quarantine can be justified? Travel quarantine is a venerable public health strategy designed to keep disease away from uninfected populations. But its use is controversial: it raises political, ethical, and socioeconomic issues balancing public interest and individual rights. Early in the COVID-19 pandemic, travel restrictions were aimed to slow or mitigate the spread of SARS-CoV-2 to heretofore unafflicted nations, a well-established approach justified by preventing or delaying disease in a country with zero prevalence. At times, strict national border control measures mandating an extensive quarantine have often been imposed between origin & destination countries that both have ongoing community transmission. Border restrictions are a politically expedient executive action. However, they provided diminishing public health benefits as the COVID-19 pandemic has progressed. Imported cases have had little impact where community transmission was well established. Dr. Townsend has investigated reasonable quarantines for travelers who have not been identified as likely infected by calculating post-quarantine transmission via country-specific imminent infections, identifying travel quarantine and testing strategies such that infections won't go up in the destination country when compared to complete border closure. The effect of travel policy on in-country transmission comes down to an import-export balance equation regarding whether travelers from a country carrying imminent infections to another faster in one direction than another. This balance can be accurately modeled. 

Bio: Dr. Townsend received his Ph.D. in 2002 in organismic and evolutionary biology from Harvard University. After that, he was appointed as a Miller Fellow at the University of California-Berkeley in the Department of Plant and Microbial Biology. In 2004, he was appointed as an Assistant Professor in the Department of Molecular and Cell Biology at the University of Connecticut. In 2006 he moved to an Assistant Professorship the Department of Ecology and Evolutionary Biology at Yale University. In 2013 he began to work on statistical approaches to fit mathematical models of disease spread and emergence, and was appointed as an Associate Professor of Biostatistics and Ecology & Evolutionary Biology, in 2017 he was named Elihu Associate Professor of Biostatistics and Ecology & Evolutionary Biology, and in 2018 he was appointed Elihu Professor of Biostatistics and Ecology & Evolutionary Biology.

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