Missouri collects and presents COVID-19 data through their public health dashboard. The dashboard provides the data by county, school district, demographics, and healthcare system. The underlying data is downloadable for researchers and others interested. Much of the data shown on the Greene County dashboard was available here, but no longer is in the same way.
Missouri no longer updates the websites as they did. Therefore, most of the following links are to the Internet Archive captures.
In the United States, the primary laws that govern collection of disease data come from the state level. In Missouri, after the legislature enacts laws, agencies write rules and regulations to implement those laws. Missouri's Code of State Regulations Rules of Department of Health and Senior Services, Title 19, Division 20, Chapter 20 covers communicable diseases (see older revisions). Missouri law required labs and health service providers to report information regarding over 100 diseases and illnesses, as of 2021. Data from these local institutions must be sent to the county health department or Missouri's DHSS. The state and local agencies report the data back and forth and reconcile it as needed.