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Apparent reductions in new daily case counts for COVID-19: real or an artifact of reduced testing?

EM SARS-COV-2 from NIAID– CC license

The daily new case counts for COVID-19 have averaged less than 50,000 for the last week. Worldometer gives yesterday’s count as 43,999 and two days ago as 40,560. After an all-time high of 78,584 on July 24, the trend has been steadily downward since. On July 30, 72,574 new cases were reported. On August 14, 60,015 new cases came in. Daily deaths have also been dropping, with less than 1,000 reported on several days.

A marked periodicity in daily deaths is obvious on the graphs shown on Worldometer– two days with lower deaths are followed by five days with higher deaths every week since April. For this reason, weekly averages offer a much clearer picture. The seven-day moving average has shown a plateau at slightly above 1,000 a day since the beginning of August.

The seven-day moving average of new cases peaked at the end of July at around 68,000 and has been dropping since– it now stands just below 50,000.

The total number of daily tests peaked at 926,876 on July 24. Thereafter, the number of tests dropped significantly, to a nadir on August 12 of 479,048. The number of tests increased, but then dropped again, to 642,814 yesterday.

The number of patients currently hospitalized has been dropping as well. The hospital number peaked at 59,718 on July 23 and is now down to 43,747 as of August 18. The previous peak was 59,940 on April 15, which then dropped to 27,967 on June 20.

The overall test positivity rate has dropped from about 8.5% to 6.5%; previously the positive rate was as low as 4.3% in mid-June. At the beginning of May, 15% of tests were coming back positive.

All the figures except the number of tests performed each day have been moving in the right direction for the last two weeks. The number of tests done each day is now about 69% of the number done each day at the peak. The number of people in the hospital has dropped quickly compared to the drop in the number of new positive cases. Test numbers are taken from the COVID Tracking Project. Positive rates are taken from Johns Hopkins Coronavirus Resource Center.

These figures appear to be moving in the right direction except for the number of tests performed each day. I have some skepticism about the hospital numbers (because CDC no longer handles them; the numbers now go directly to HHS) but there is no obvious reason to doubt them.

One Comment leave one →
  1. 2020-08-20 4:27 AM

    Up until the past month I really didn’t know anyone that had it, but now I know several. The ones I spoke with or read the updates all started treatment at first symptoms, even before test results and seem to do ok. So maybe treatment has improved resulting in less deaths


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