Thread by @exceedhergrasp1

Today, someone told me that a negative test "proves the person never had COVID" (in ref to #LongCOVID).
Should we list, AGAIN, the reasons why "no + COVID test" is NOT a reason to assume the person didn't have COVID?
yes, yes we should! A🧵(1/9)

First, and this may be new to some of you: as Dr. William notes, COVID testing seems like it is not catching some of the newer variants. (2/9)

https://twitter.com/DrCSWilliam/status/1457708785720569867

Second, early testing sucked. If you got tested early (first half of 2020) with all the symptoms of COVID but came up negative, you may well have had a false negative. One test kit sent to laboratories had a 33% fail rate. (3/9) npr.org/2020/11/06/929…

Third, early testing was inaccessible. Many who caught COVID-19 in March/April 2020 did not receive a test.
"In CA... 1138 people had been tested for the virus... despite several thousand who have likely been exposed" said The LA Times in March 2020. (4/9)
latimes.com/california/sto…

"But if you test them later, then surely we would know if they'd been exposed..."
Not necessarily.
Antibodies to SARS-CoV-2 may not last forever, especially if the initial infection was mild.
*Note: I found conflicting info on this one. (5/9) uclahealth.org/u-magazine/cor…

Finally, testing is/was/will always be a privilege. If you can't take off work to see the doctor or you'll get fired, you aren't getting tested. If you don't have health insurance and aren't sure where to get free care, you won't get tested. (6/9)

@CDCgov has a set of clinical criteria for "likely COVID-19" b/c they understood all these obstacles in testing. ndc.services.cdc.gov/case-definitio…

Finally, not having a positive test doesn't mean you never had COVID: it just means you can't prove that you did. (7/9)

I'm sure there's a name for this fallacy, because it's everywhere in science discourse.
Fallacy ahoy!
(If no one has proved it's true, that means it's false).
But... that's not how this works. That's not how any of this works.
(8/9)

I'm sure there is more, but this is plenty of reason to take it on board that many people with COVID would not have received accurate (or any) COVID testing. (9/9)

Courtesy of convo with @benedictecallan:
As per earlier convo with @ahandvanish, there are millions upon millions of never-diagnosed cases. Early in the pandemic numbers were estimated to be 10:1 undiagnosed to diagnosed. Now it's more like 3:1. charlotteobserver.com/news/coronavir…

In addition, not everyone mounts a robust adaptive immune response in the first place. #pwME were COVID-diagnosed but then later "failed" antibody testing. People without robust adaptive immune function may survive by relying on innate immune function (non-specific responses).