  Since the World Health Organization announced the COVID-19 pandemic in March
2020, curbing the spread of the virus has become an international priority. It
has greatly affected people's lifestyles. In this article, we observe and
analyze the impact of the pandemic on people's lives using changes in
smartphone application usage. First, through observing the daily usage change
trends of all users during the pandemic, we can understand and analyze the
effects of restrictive measures and policies during the pandemic on people's
lives. In addition, it is also helpful for the government and health
departments to take more appropriate restrictive measures in the case of future
pandemics. Second, we defined the usage change features and found 9 different
usage change patterns during the pandemic according to clusters of users and
show the diversity of daily usage changes. It helps to understand and analyze
the different impacts of the pandemic and restrictive measures on different
types of people in more detail. Finally, according to prediction models, we
discover the main related factors of each usage change type from user
preferences and demographic information. It helps to predict changes in
smartphone activity during future pandemics or when other restrictive measures
are implemented, which may become a new indicator to judge and manage the risks
of measures or events.
