Determine Arrival Time of Variant in Target Region

Determine the precise arrival time in a specified country of a SARS-CoV-2 variant that is spreading in other countries, given only observations from regions where the variant has already emerged and before it has appeared locally.

Background

The paper motivates the need for predicting when a new SARS-CoV-2 variant will arrive in a country by noting that variant-driven surges depend heavily on timing. While the properties of a variant can be inferred from places where it is already spreading, the exact timing of its arrival in another region critically informs preparation and resource management.

Existing statistical methods require the variant to have already appeared locally at non-zero prevalence, leaving unaddressed the problem of predicting arrival time when local prevalence is still zero. The authors frame this as a delay prediction task and develop dynamics-informed models, but explicitly acknowledge that the timing is initially unknown, motivating the problem.