I would guess that all states have something like this, but here is an update as of today from the Arizona Department of Health Services (ADHS). (Bold emphasis mine.)
Unexpected increase as a result of changes in surveillance reporting!
As our federal partners have updated guidance for identifying COVID-19 deaths, ADHS has enhanced our processes to match. This change may cause the number of new deaths reported on our dashboard to increase more than expected for a few days.
Unexpected increases due to addition of antibody testing!
Today we updated our dashboard to include additional information about laboratory testing for COVID-19 in Arizona. This new enhancement provides a look at antibody testing for the first time. Previously, data on the ADHS dashboard only included diagnostic (PCR) testing information. While we had been getting a small number of serology results reported to the Department over the past three weeks, a large number of serology results were reported this past week as testing capacity has expanded.
Unexpected increases due to other coronaviruses that cause the common cold!
Antibody (also known as serology) tests are laboratory tests that look for the presence of antibodies, which are made by the body in response to an infection. Antibody testing for COVID-19 is relatively new, so it is difficult right now to draw conclusions about antibody testing data. Additionally, an antibody test may be falsely positive for COVID-19 because the test may have detected the presence of antibodies to other coronaviruses that cause the common cold.
This information is provided as a public service without comment — well, okay if you insist — just one.