The Centers for Disease Control (CDC) has been the gatherer and investigator of disease trends in the U.S. since 1946. That said, they no longer collect the actual COVID data from states and hospitals but get it from their parent agency, the Health and Human Services. See below for an explanation. They remain the best source for most nationwide COVID-19 data due to their data quality checking procedures.
On March 29, 2020 Vice President Mike Pence asked hospital administrators to submit spreadsheets about certain COVID-19 information daily to a FEMA email address. On July 10, other guidance was given by HHS that stated information should be sent to a new system at HHS. Part of this guidance was also that hospitals were not to submit data to the CDC anymore. A modified version of that guidance was sent out as a memorandum by HHS on October 6. A further revised version of the guidance is online from December 8.
If state health agencies collect data and submit it to HHS in a specified manner then hospitals did not have to do it directly. Missouri is not listed as a state that can submit information in this manner. The graphic on the Home page of this library guide therefore doesn't quite match reality for COVID-19 reporting.
Following are links to COVID related research that doctors and scientists can use for research projects.