The accelerated infectious disease risk in the Anthropocene: more outbreaks and wider global spread

Serge Morand; Bruno Andreas Walther

Theoretical models predict that increased mobility leads to a faster and more wide-ranging spread of a disease outbreak, and, vice versa, decreased mobility slows and contains the spread of an outbreak. Modelling the spread of the SARS-CoV-1 pandemic, Hufnagel et al. (2004) demonstrated that two control strategies, shutting down airport connections and isolating cities, reduced the spread of the virus. Drastic travel limitations also delayed a pandemic by a few weeks in a model of the global spread of influenza (Colizza et al., 2007) . Similarly, increasing levels of (1) isolation of infectious hosts, household quarantine and related behavioral changes which reduce transmission rates and (2) air traffic reduction increasingly slowed the global spread of influenza, although the latter control strategy required the almost complete halt of global air traffic (Cooper et al., 2006; Ferguson et al., 2006; Flahault et al., 2006; Hollingsworth et al., 2006; Epstein et al., 2007; Bajardi . CC-BY-NC-ND 4.0 International license author/funder. It is made available under a The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/2020.04.20.049866 doi: bioRxiv preprint 11 et al., 2011). Epstein et al. (2007) emphasized that a combination of both control strategies would be even more effective, a result mirrored by Mao (2011) for a model at the city scale. Crucially, Hollingsworth et al. (2006) also showed a significant decrease in the number of countries affected if travel reductions are combined with other control strategies to reduce transmission rates. This result was confirmed by Cooper et al. (2006) and Flahault et al. (2006) who found that fewer cities (distributed around the world) were affected by major outbreaks if sufficiently early and significant travel and transmission reductions were implemented. In a simulated smallpox attack, even gradual and mild behavioral changes had a dramatic impact in slowing the epidemic (Del Valle et al., 2005) .