Before revision: This paper proposes a cluster-based method to analyse multivariate systems that change over time . We apply this method to analyse the evolution of COVID-19 cases and deaths, partitioning data points into an appropriate number of clusters on each day to track both the  total number of clusters and their changing constituency over time .
After revision: This paper proposes a cluster-based method to analyze the evolution of multivariate time series and applies this to the total number of clusters and their changing constituency over time .