COVID numbers getting redefined again?
In a world of "lies, damned lies, and statistics," we should consult the SARS-Cov-2 (COVID-19) source data to understand the current numbers and the methodology for classifying new cases and deaths.
According to the CDC website, as of April 18, there were 690,714 total cases and 35,442 total deaths. A footnote says the total cases include 1,282 probable cases and the total deaths include 4,226 probable deaths, which is 12% of the total deaths after only four days of counting probable deaths. This is probably the result of the new definition of "probable death" (see below).
The CDC began counting confirmed and probable cases and deaths on April 14, two days before President Trump announced his plan for states to reopen the economy, based on guidance provided by the Council for State and Territorial Epidemiologists (CSTE) on April 5.
The guidance for probable COVID-19 cases and deaths includes three options: (1) meets clinical criteria and epidemiologic evidence with no confirmatory laboratory testing performed, (2) meets presumptive laboratory evidence and either clinical criteria or epidemiologic evidence, or (3) meets vital records criteria with no confirmatory laboratory testing performed.
This guidance includes definitions for clinical criteria, epidemiologic evidence, presumptive laboratory evidence, and vital records criteria, but the threshold for "probable" seems "possible" in some cases. For example, for option 1, anyone who dies with a cough (clinical criteria, check) and exposure to a hotspot (epidemiologic evidence, check) could qualify as a probable COVID-19 death. Each option points to COVID-19 as a possible cause of death, but the absence of confirmatory laboratory testing weakens the "probable" claim. This new guidance will probably inflate the numbers, but the official CDC numbers presented in the media do not distinguish between probable and confirmed deaths.
The guidance for confirmed cases and deaths is defined by confirmatory laboratory evidence, which means the detection of SARS-CoV-2 RNA in a clinical specimen using a molecular amplification detection test. That is, the mere presence of the SARS-CoV-2 RNA in laboratory evidence is sufficient to classify a confirmed COVID-19 death. This is clearly not confirmation, because someone could test positive for COVID-19 but die from other causes, such as seasonal flu or pneumonia, and thus will probably inflate the numbers as well.
According to Professor Walter Ricciardi, scientific adviser to Italy's minister of health, "[t]he way in which we code deaths in our country is very generous in the sense that all the people who die in hospitals with the coronavirus are deemed to be dying of the coronavirus[.] ... On re-evaluation by the National Institute of Health, only 12 per cent of death certificates have shown a direct causality from coronavirus, while 88 per cent of patients who have died have at least one pre-morbidity — many had two or three."
As in Italy, it is not clear why we would categorize every person who dies with a COVID-19 infection a confirmed COVID-19 death, if by confirmed we mean a causal relationship. In many cases, it would be more accurate to say COVID-19 was a contributing factor and to track the contributing factors as well. Otherwise, as we have seen with the faulty computer models, inflating the numbers will result in the misallocation of resources to fight COVID-19.
Due to the new guidance, we might see an artificial rise in COVID-19 cases and deaths that will distort the flattening of the curves that was based on the previous guidance. This should be taken into consideration as states implement President Trump's plan to reopen the economy. One way to do this is to redraw the old curves, to offset a misleading rise of cases in mid-April due to the new guidance.
The timing for the new guidance was less than ideal (the curves were flattening while states were reviewing guidance to reopen the economy) and opens the door for hospitals and politicians to inflate COVID-19 numbers to receive government funding. The CDC should do a better job of educating people on the implications of this new guidance, to include explaining "probable" and disentangling the COVID-19 numbers from other contributing factors.