  The ongoing COVID-19 pandemic has profoundly impacted people's life around
the world, including how they interact with mobile technologies. In this paper,
we seek to develop an understanding of how the dynamic trajectory of a pandemic
shapes mobile phone users' experiences. Through the lens of app popularity, we
approach this goal from a cross-country perspective. We compile a dataset
consisting of six-month daily snapshots of the most popular apps in the iOS App
Store in China and the US, where the pandemic has exhibited distinct
trajectories. Using this longitudinal dataset, our analysis provides detailed
patterns of app ranking during the pandemic at both category and individual app
levels. We reveal that app categories' rankings are correlated with the
pandemic, contingent upon country-specific development trajectories. Our work
offers rich insights into how the COVID-19, a typical global public health
crisis, has influence people's day-to-day interaction with the Internet and
mobile technologies.
