Novel coronavirus disease (COVID-19) has spread across the world at an unprecedented pace, reaching over 200 countries and territories in less than three months. In response, many governments denied entry to travellers arriving from various countries affected by the virus. While several industries continue to experience economic losses due to the imposed interventions, it is unclear whether travel restrictions were successful in reducing COVID-19 importations. We developed a comprehensive probabilistic framework to model daily COVID-19 importations into a given country, considering various travel restriction scenarios. We quantify the temporal effects of the restrictions and elucidate the relationship between incidence rates in other countries, travel flows and the expected number of importations into the country under investigation. As a cases study, we evaluate the travel bans enforced by the Australian government. We find that international travel bans in Australia lowered COVID-19 importations by 87.68% (83.39 - 91.35) between January and June 2020. We further show how the framework can be used to gain insights into the expected number of importations should borders re-open. While travel bans lowered the number of COVID-19 importations overall, the effectiveness of bans on individual countries varies widely and directly depends on the change in behaviour in returning residents and citizens. Authorities may consider the presented information when planning a phased re-opening of international borders.

About Mathematical biology seminars

We present regular seminars on diverse topics in mathematical biology. The seminars often show how dynamical systems, probability, or other mathematical techniques help us understand and manage biological systems, from microscopic cells to the world's largest ecosystems.

All are welcome, and past audiences have been diverse. The majority of the audience is made up of applied mathematicians, but pure mathematicians, biologists, and other scientists often attend as well.

Talks should be pitched at a level such that HDR students in mathematics and quantitative biology are able to understand the content.

These seminars are held at various times throughout the year.


Priestley Building (67)
442 (and via zoom. Please email for Zoom login credentials)