Plan B Forum

The Food and Drug Administration issued an emergency approval Tuesday for a serological testing kit produced by Bodysphere Inc. that can detect a positive or negative result for COVID-19 in two minutes.

Why it matters: Access to testing has improved in the U.S. thanks to commercial labs, but the average wait time for a patient's results is four to five days — with some reports of it taking more than a week.

These antibody tests could help people know if they are able to go back to work, as well as aid researchers in tracking the scale and death rate of the disease — key data for current and future pandemic policies.
They're especially useful for determining whether health care workers have some immunity and are at lower risk if they go back to work.

What's happening: The FDA has been rushing to approve tests from companies that promise quicker results.

https://www.axios.com/fda-coronavirus-t ... jjx1eF-g_4

Good news so long as the test is properly vetted; antibody tests are notoriously inaccurate when cross reactivity against other strains is considered (and there are a number of other coronaviruses in corculation), which could lead to false posivives. Hopefully, the FDA has done the approval properly and did not rush to judgment.

Stop being such a fearmongering naysayer Big RR...

Big RR wrote: ↑

Tue Mar 31, 2020 5:38 pm

Good news so long as the test is properly vetted; antibody tests are notoriously inaccurate when cross reactivity against other strains is considered (and there are a number of other coronaviruses in corculation), which could lead to false posivives. Hopefully, the FDA has done the approval properly and did not rush to judgment.

We all know the FDA never makes mistakes Big RR. Nor do the other federal agencies screw up ... except for the incompetence demonstrated by FEMA, the CDC, the FBI, the CIA ... hmmm ... might as well list them all.

It's truly amusing when a Trump supporter claims to care about competence...

Almost as hilarious as when they attack someone for being "dishonest", or "corrupt"...

Not to mention that the agencies are not immune to pressure from the top, nor are Trump and his handlers reluctant to provide the pressure.

Not to mention that the agencies are not immune to pressure from the top, nor are Trump and his handlers reluctant to provide the pressure.

But FWIW, there is a big difference between making a mistake and taking a risk.

This test is an immunoassay - essentially you look for the COVID antibodies by creating an antibody (AB) to the COVID antibody (COVAB). You then add some AB to the sample of blood; wait for COVAB to react with all the AB you have added; then add something which turns the unreacted AB green or purple or whatever. Measure the amount of purple color.

So suppose there are 30 units of COVAB in the blood. Add 100 units of AB. 30 units of the AB will drop out because it bonds with the COVAB which means that there are 70 units of AB which are unreacted. Drop in the color reagent which turns purple ONLY when it bonds with the virgin AB; so you get 70 units of color. Figuring out how much COVAB there is in the blood is just simple arithmetic. All immunoassays are variations on this theme which I have simplified a little for the purposes of this note.

No test is 100%. Even a good test is 97% accurate, so let's use that number. From a public health point of view, false positives are preferable to false negatives - you much prefer to treat someone unnecessarily as a result of a false positive than let someone go out there who has the virus but tested negative - a false negative. So let's assume that the test is weighted so that it's 100% accurate for positives - it never misses. That means that it is 97% accurate for negatives: 3% of the time it gets it wrong and says someone is positive when they are not.

Suppose also that COVID-19 is relatively rare. It occurs in only 1% of the population. I'll use that to keep the arithmetic simple.

What happens then when you test 1000 people? 1% - 10 people - are in fact positive. The test finds all of them. The 990 people who are negative also get tested and this time 30 of them test positive. That's the 3% failure rate. It's a very good test: 97% accurate. But the net effect is that 40 people out of the 1000 test positive, but only a quarter of these people are in fact positive.

It's a real problem; it's basic statistics; and it may yet haunt us. This rapid test is great but it will have its own set of problems.

No test is 100% accurate. In this situation it is entirely appropriate to aim for false positive rather than letting false negatives slip out of the containment.

snailgate

Coming soon to a hospital near you if it's not already there.

"Dr. Marcus Zervos is an infectious disease specialist at Henry Ford. He says staff at Henry Ford has been using hydroxychloroquine to treat the most severe cases of COVID-19 in hospitalized patients.

“We are not using it in outpatients, we're not using it in patients with mild infection, we are using it, however, in patients that are sick enough to be hospitalized with pneumonia that we feel are at risk of progressing their infection.”

He adds,“We feel that there is data both from the early published studies as well as from our colleagues in China that have treated a number of patients to justify its use
in the therapy of sicker patients that are hospitalized with coronavirus infection.”"


https://www.michiganradio.org/post/henr ... eigh-risks

What Dr. Zervos chose not to say, was that he saw any clinical benefit in the patients being treated at Henry Ford. One can only wonder why...

Once again, Darren buries the lead... (from his link)

He’s quick to mention, however that hydroxychloroquine is not the end-all-be-all or a miracle cure: doctors are using it because they think the benefits outweigh the risks.

“I don’t want to give the idea that hydroxychloroquine is the only treatment, or is going to be some sort of a miracle cure. Really, that still has to be looked at in a formal, clinical trial, we still need more data,” he says.

Additionally, I notice that while the Doctor touts other studies (without citing any specifically) he has nothing at all to say about what results he has been getting...

ETA:

I see Scooter beat me to the punch on the last point...

But it's worth making it twice...

Doesn't justifying a medication for use for the sickest patients mean that doctors use it at a point where they think the risk is worth taking? That doesn't sound very encouraging to me. Time will tell...

Scooter wrote: ↑

Wed Apr 01, 2020 3:08 am

What Dr. Zervos chose not to say, was that he saw any clinical benefit in the patients being treated at Henry Ford. One can only wonder why...

Different editors/writers perhaps when the interview was edited.

"Zervos said the drug, an arthritis medicine also used to treat malaria, isn’t seen as a “miracle cure" but [b]has shown some success[/b] in managing a virus that currently has no remedy."

https://www.mlive.com/public-interest/2 ... tment.html

Once again, the words that aren't there are that said success has been shown in patients he has treated.

Try harder.

Once again, the ONLY reason you are cheerleading for this treatment is that Trump prematurely called it a "gamechanger", and you are duty bound to defend your Fuhrer.

I can attest from overhearing my wifre work called that Henry Ford is not at the forefront of Coronavirus treatment. The preparations thar are making are far more grim. Preparations no one would make if they had an end in sight.