On Sept. 24 and 25, the Alabama Department of Public Health reported many backlogged positive probable cases, causing a spike in cases. At the same time, ADPH also began including “probable” cases in its county-by-county data, which we use to populate our graphs, causing what looks like an even larger surge in cases and deaths in most counties. Rather than a true surge, the increase is a function of older probable cases and deaths being added to the cumulative count. We do not have the ability to back date that data. The increase also affected our 7- and 14-day averages. For more information, read this notice.
The misnomer of “probable” and “confirmed” largely is a differentiation between cases confirmed through PCR and antigen testing.
Confirmed cases of COVID-19 represent persons who have positive PCR tests, whether symptomatic or not. Probable cases of COVID-19 currently represent two groups: Those who are epidemiologically linked to a case (exposed to a person who had COVID-19), have symptoms compatible with COVID-19, and do not have diagnostic tests performed due to individual decisions or other reason.
The other group of persons categorized as probable cases are people who have had rapid antigen tests performed. Rapid antigen tests, while diagnostic tests, are counted as probable due to antigen tests showing lower ability to determine if a person has SARS-CoV-2. In other words, point of care antigen tests are less sensitive and show more false negative results than laboratory performed PCR tests.
Confirmed and probable cases are investigated and contacts identified in the same manner. As more antigen diagnostic testing has been approved, the proportion of probable cases in Alabama continues to rise. As more healthcare providers use antigen testing, that trend is expected to continue. Probable cases are now being included in totals to best represent the current situation.
Positives above and cases anywhere on this dashboard include both positive “confirmed” and positive “probable” cases. Beginning on Sept. 1, the Alabama Department of Public Health began including probable cases in statewide totals. Beginning on Sept. 25, ADPH began included probable cases in county-by-county totals. We saw large increases in case totals on those dates due to the addition of older probable cases.
“Hospitalized” refers to daily hospitalizations of cases, as reported by the Alabama Department of Public Health via the Alabama Incident Management System. Data is affected by the number of hospitals that report.
“Recovered” includes those who are presumed to be recovered and is updated once a week.
Unless otherwise noted, tested totals on this dashboard include only diagnostic tests including PCR tests and antigen tests, which identify active cases of COVID-19. Totals, unless otherwise noted, do not include antibody tests, which do not identify active cases of COVID-19. ADPH separated antibody from diagnostic tests in its data on Sept. 1. For more information about that change, read this notice.
Unless otherwise noted, deaths on this dashboard include both “confirmed” and “probable” deaths. ADPH began including probable deaths in statewide totals on Sept. 1 and in county-by-county data on Sept. 25.
“Today” indicates the reported increase in cumulative totals reported from 12 a.m. to 11:59 p.m. on the day indicated in the timestamp on the top of the dashboard. It does not reflect cases, tests or deaths that occurred today — but rather the date on which they were reported.
Different trackers (like COVID Tracking Project, Johns Hopkins University and others) have different cut-off times, so cumulative totals reported may be slightly different. Our cut-off time is 12 a.m. to 11:59 p.m. We capture the cumulative totals at throughout the day and end each day with the total as publicly reported at 11:59 p.m. Other trackers end earlier, for example, COVID Tracking Project cuts off at 5:30 CT. This has become less of an issue as the Alabama Department of Public Health moved to once daily updates.
It is two different measurements of the same phenomenon. We also display ADPH’s calculations of daily case counts in addition to ours. To explain how we calculate that number: We capture the cumulative total as displayed on ADPH’s public-facing dashboard from 12 a.m. to 11:59 p.m. each day. That is the main, top-line number you see at the top of their dashboard under “POSITIVES.”
We take the cumulative total of confirmed cases at 11:59 p.m. on one day and subtract the cumulative total at 11:59 p.m. from the previous day. That is how we arrive at the “daily increase in cases.” We update this number for the current day until 11:59 p.m. For example, the cumulative count at 11:59 p.m. on May 23 was 14,149, according to ADPH’s dashboard. The cumulative count at 11:59 p.m. on May 22 was 13,670, according to ADPH’s dashboard. That is an increase in the cumulative total of 479 in a 24-hour period.
Generally speaking, our daily case counts are not much different from ADPH. But on some days, they are quite different because the top-line number on the public ADPH dashboard may not have updated. ADPH’s daily case total is kept internally and is separate from the cumulative total displayed on the public-facing dashboard. So, for example, they show May 22 ending with a cumulative total of 13,777 on their daily charts. The topline number on the dashboard showed 13,670 at 11:59 p.m.
Though daily increases can be interesting and telling, looking at an average over a longer period is a better reflection of the situation and better reflects trends. This is why we suggest looking at 7-day and 14-day averages instead of individual day increases.
