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Why You Might See County COVID-19 Numbers Go Up and Down

Last Updated on May 19, 2020 at 12:42pm | Communications Office
By Garrett County Joint Information Center Team
If you have been watching the numbers on the Maryland COVID-19 Data Dashboard over the last few days you have seen the numbers for Garrett County go up and back down several times. There are many reasons why the numbers could change.
First of all, the numbers on the map are preliminary. In fact, below the map it says, “All data are preliminary and are subject to change based on additional reporting.”
In Maryland, the numbers on the map are generated from a database where all the COVID-19 tests are reported. Once a positive case shows up in the database, staff at the health department for the county where the positive case is assigned begin to investigate the case.
Here are some of the issues that may cause a case to be assigned to the wrong county:
  • An incorrect address may have been recorded at the testing site and reported to the state.
  • The patient may have two different homes, in two different states. Research is needed to determine which is the primary residence.
  • Sometimes a person is tested a second time, and the case needs to be removed to avoid counting it a second time.
  • The automated system may mistakenly assign a case to the wrong county.
Why is it important to get it right? Because the county of primary residence is responsible for contact tracing, the process that finds close contacts of a positive case and lets them know that they need to quarantine so they don’t spread the virus if they have been infected.
When a case needs to be transferred to another county, or another state, there is often a delay of a day or two before the case is changed on the map.
Once the preliminary investigation is completed, the testing results are counted in the county of primary residence.
Key staff at both the local and state level are paying close attention to, and immediately investigating, any positive COVID-19 results. Information is shared across county and state lines as necessary to protect residents and health care workers in this ongoing pandemic, while safeguarding the privacy of anyone testing positive for COVID-19.
Another question many are asking is why the data doesn’t show up for any Garrett County zip codes. Again, the explanation is under the map, where it says, “Data for ZIP codes with 7 or fewer cases are suppressed.” None of the Garrett Counties zip codes show up in the reports, because the county does not have any zip codes with enough cases to show up on the list. The zip codes for low number locations are not reported to prevent specifically identifying a positive case within a small community.
Accurate COVID-19 information is critical to the community. Please visit the Health Department COVID-19 Dashboard at for current and accurate information about the situation.