What Drs. Fauci & Birx said about testing…

I watched, so that you wouldn’t have to…
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During the press conference yesterday, Drs. Fauci, Birx, et. al., gave a technical presentation intended to educate us on their testing plan (and fend off critics like Gov. Cuomo).

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In general, I was frustrated by the presentation which was way more “academic” and credential-building (e.g. “what we did re: HIV”) than practical (i.e. here’s what we’re going to do and how it impacts you) … and, still didn’t answer many of my questions (e.g. going forward, exactly who will be tested? how & where will they be tested? how will the test results be used? how can I get a test? what are my odds of getting infected? why does testing require a doctors Rx note? what about the false negative problem?).

As expected he dufass politico reporters asked no meaningful drill-down questions.

That said, I drew some significant takeaways from the presentation …

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Point of emphasis: There is adequate testing capacity deployed to support the phased Open America plan. But, “the full potential of testing capacity still needs to be unlocked.” Birx

But, testing  is only a supporting component of the plan and is not “the panacea”   … it’s a diagnostic tool and a source of information for policy-setting … more testing will not stop the virus … it will help for priority-setting but we’ll still dependent on social-distancing and therapeutic interventions.

More specifically…

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Paraphrased, here’s what they said …

Testing modalities – There are 3 different types of testing aimed at diagnosis, surveillance and antibody presence.

Diagnosis (now): Confirm that symptomatic patients are infected (mostly to ration hospital capacity by sending home those who test negative); test caregivers (symptomatic & asymptomatic) to isolate them from patients if infected, treat them and clear them when recovered.

Diagnosis (prospective): Identify infected patients … and then identify and test their closest contacts (and prescribe treatment if they test positive).

Surveillance: Determine the incidence of infections in both symptomatic and asymptomatic people … in specific areas (i.e. apparent hot spots), at specific times (e.g. when there are anecdotal indications of heightened spread)

Antibody testing: Test recovered C-19 patients to determine if they have extractable antibodies that can be plasma-transfused to current patients; test randomly to identify asymptomatic (untreated) patients, in part to estimate the virus’ spread to date.

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Re: Diagnostic testing – There are 2 basic diagnostic testing “platforms” (and, at a practical level, they are very different)

High throughput lab tests: Done by commercial and university labs … process dozens of samples at a time; potentially thousands in day … sample taken at medical facility (e.g. hospitals), shipped away to labs, reports transmitted back … bottom line: 48-hour turnaround, longer when backlogged

The task force asserts that there is substantial lab test capacity and that the labs currently have excess capacity.

Abbott Rapid Tests: A point-of-care solution … e.g. testing “machines” in hospitals or doctor offices … fast turnaround: 15 minutes to get results

But, capacity is limited: 4 tests per hour per machine; less than 100 tests per day per machine.

In aggregate, there are approximately 18,500 testing machines installed … “aggregate throughput capacity of the rapid tests is dwarfed by lab testing capacity”. Giroir

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Re: Surveillance testing – “The only sure way to know how many people are infected (i.e. carriers who might infect others) is to test the entire population every day.” Fauci

Why every day? Just because a person tests negative today doesn’t mean they won’t be infected tomorrow or the next day.

Why not? It’s not practical (or feasible) to do 325 million tests each day

So what? Need to concentrate on apparent hot spots and do random testing there.

Which hot spots? Metro areas and nursing homes

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Re: Antibody testing – Many testing modalities will soon be available

Dual objective: Test recovered C-19 patients to determine if they have extractable antibodies that can be plasma-transfused to current patients; test randomly to identify asymptomatic (untreated) patients, in part to estimate the virus’ spread to date (since the antibodies can only be present if the patient had been infected)

The elephant in the room: It is implicitly assumed that infected patients (who have recovered) have antibodies that protect them from subsequent re-infection.

But, it is not known with certainty whether the antibodies are sufficient to protect from re-infection … and, if they are, whether the protection is transient or permanent … and, if transient, for how long?

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I think many of these takeaways provide helpful clarifications … but, there are implications and open questions that I intend to cover in subsequent posts.

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