Here's more information form their website:
'Objective and internationally comparable data are crucial to determine the effectiveness of different strategies used to address epidemics. Weekly death counts provide the most objective and comparable way of assessing the scale of short-term mortality elevations across countries and time. We provide weekly death counts for 25 countries: Austria, Belgium, Bulgaria, Czech Republic, Denmark, Belgium, England and Wales, Estonia, Finland, France, Germany, Hungary, Iceland, Israel, Italy, Lithuania, Luxembourg, Netherlands, Norway, Portugal, Scotland, Slovakia, Spain, Sweden, Switzerland and the USA. The same data in the pooled CSV file are available for download. Data formats and methods are described in the STMFNote. We also strongly recommend reading the metadata text. Following the HMD practice, we also publish original input data in standardized format. During the next few weeks data will be frequently updated and new countries will be added. The most recent STMF update is: 2020-07-08."
"New: We invite you to explore this data with our online STMF visualization toolkit."
More information about The Human Mortality Database. "The Human Mortality Datbase (HMD) was created to provide detailed mortality and population data to researchers, students, journalists, policy analysts, and others interested in the history of human longevity. The project began as an outgrowth of earlier projects in the Department of Demography at the University of California, Berkeley, USA, and at the Max Planck Institute for Demographic Research in Rostock, Germany"