Aggregate Data Collection Process Since the start of the COVID-19 pandemic, data have been gathered through a robust process with the following steps: A CDC data team reviews and validates the information obtained from jurisdictions’ state and local websites via an overnight data review process. If more than one official county data source exists, CDC uses a comprehensive data selection process comparing each official county data source, and takes the highest case and death counts respectively, unless otherwise specified by the state. CDC compiles these data and posts the finalized information on COVID Data Tracker. County level data is aggregated to obtain state and territory specific totals. This process is collaborative, with CDC and jurisdictions working together to ensure the accuracy of COVID-19 case and death numbers. County counts provide the most up-to-date numbers on cases and deaths by report date. CDC may retrospectively update counts to correct data quality issues.