From the WebMD Archives

April 13, 2020 -- With more than 90% of the country unable to leave home for work or school, officials have said one thing might help us get back to normal: a rapid blood test to see if someone has developed immunity to COVID-19.

Serologic tests, as they’re called, look for antibodies in the blood. Antibodies develop when you’ve been exposed to a particular infection, and experts believe many COVID-19 cases are so mild people may not know they had it. That means there’s a chance a significant number of us have developed antibodies already.

Module: video
photo of Vincent Racaniello
 
Coronavirus in Context: Immunology Expert Discusses Testing, Antibodies, and MoreAn immunology expert describes various tests for coronavirus, whether we’re immune to COVID-19 after infection, and more.818

[MUSIC PLAYING]



JOHN WHYTE, MD, MPH: Welcome

to Coronavirus in Context.

I'm Dr. John Whyte, Chief

Medical Officer at WebMD.

Everyone's been talking

about testing.



First, we talked

about diagnostic testing.

Now we're talking about antibody

testing.

But is that really the way

that we're going to get back

to work and open up the country?



My guest today is Dr. Vincent

Racaniello.

He's professor of microbiology

and immunology at Columbia.

Thanks for joining me,

Dr. Racaniello.



VINCENT RACANIELLO, PhD:

Good to be back, John.



JOHN WHYTE: Let's start

with the basics.

What's the difference

between antibody testing

and diagnostic testing?



VINCENT RACANIELLO: So

a diagnostic test will tell you

if you're infected at the moment

the test is taken.

You typically give

a nasopharyngeal swab.

They look for -- in the lab,

they look for nucleic acid

of the virus by an amplification

method called PCR.

And that tells you if you're

infected.

But of course, it only works

as long as the virus is in you.



JOHN WHYTE: Mm-hmm.



VINCENT RACANIELLO:

And an antibody test will tell

you if you were

infected last week, last month,

or even last year,

or 10 years ago.

So it's a permanent record

of the infection,

long after it's over.



JOHN WHYTE: So I'm going to come

back to that -- whether it can

tell if you are immune from

a week ago.

Because there's some issue of --

of timing.

But let's talk about how

these tests are done.



And there's

different strategies.

And we hear a lot

about these "point of care"

tests that you would do

with a fingerprint.

And, um, I saw a memo recently

that talked about these tests

are actually authorized

by the FDA, not approved.

So there's a lower standard

of accuracy.

Is that right?



VINCENT RACANIELLO: That's

right.

These rapid tests, which you do

with a little bit of blood

from a pinprick on your finger,

they work in about 15 minutes.

They're dipstick tests, sort

of like a pregnancy test

that you put some urine on.



JOHN WHYTE: The first time,

yeah.

Mm-hmm.



VINCENT RACANIELLO: They develop

rapidly.

And they can give you an answer.

But they're not hugely accurate.

They're good for a broad swath

of what's going on out there.

We have them for influenza virus

infection [INAUDIBLE].



JOHN WHYTE: Yeah, but those have

been approved

outside of a public health

declaration.

And the FDA commissioner, just

a day or so ago,

said there are a lot

of inaccurate tests out there

which could give people

misinformation.

Now, what about the fact

that these are qualitative

tests?

Are they not the ones that

we're currently talking about --

either you have antibodies

or you don't?

And that's good enough.



VINCENT RACANIELLO: Yeah

that's a really --



JOHN WHYTE: Is that good enough?



VINCENT RACANIELLO: -- really,

really important point.

It will just tell you yes or no,

not how much immunity you

have, right?

So it won't tell you if you're

protected from another infection

and whether you're safe enough

to go back to work.

It's just going to say yes

or no.



JOHN WHYTE: Well, but why are we

talking about them then?



VINCENT RACANIELLO: Well,

that's --



JOHN WHYTE: It's good enough?

Are they good enough?



VINCENT RACANIELLO: [CHUCKLES]

That's a great question.

I think it's good to know who's

been infected.

Essentially, we're going to take

a chance.



These are the fastest tests

we can get out there.

We can test the most number

of people with them.

Because the alternative is a lot

more time-consuming.

And we're going to see if that's

good enough to tell us

whether you can go back to work

or not.

Because that's really the goal.



JOHN WHYTE: But you might be

exposing people, um,

to infection.

If they're not truly recovered,

they could still be infecting

others, right?



VINCENT RACANIELLO: I'm not

so concerned about that.

I think, if you wait long enough

after the end of illness --

of clinical illness -- you know,

if you wait a certain amount

of time, you're probably not

shedding.

You know, this infection peaks

in a healthy person

with an uncomplicated illness

in about seven to 10 days.

And so I think, after two weeks

or so, you're not shedding that

much.



The real concern here for me is

whether you're really OK to go

back in the workforce --



JOHN WHYTE: Right.



VINCENT RACANIELLO: -- where you

might encounter other

infections.



JOHN WHYTE: Now, without giving

us an immunology lesson, you

know, is there some data that

says --

you know, there's IGM,

there's IGG, there's IGA, which,

you know, we can send people

to to find out more.

But is it really you have

to wait 20, 28 days after you've

been infected to find

these neutralizing antibodies,

which really are what we need?

Isn't it?



VINCENT RACANIELLO: Well,

the neutralizing antibodies will

protect you.

But of course, these rapid tests

will not distinguish between --



JOHN WHYTE: No.



VINCENT RACANIELLO: -- those

and any other antibody against

SARS-CoV-2.

But you do start making

these antibodies

seven to 14 days after you're

initially infected.

And IGM, as you mentioned,

they come up first.

They last about two months.



And then IGG are

the long-term-lasting ones.

And that's another issue.

The IGM can cross-react

with other coronaviruses.

So if you're just looking

for that, that's not

a good test.

You have to look for both.



JOHN WHYTE: Now, Dr. Fauci has

said we're going to consider

giving these certificates

of immunity to people.



VINCENT RACANIELLO: Mm-hmm.



JOHN WHYTE: Is --

are they going to be valuable

at all?

Will that really tell us?

Because aren't what we really

saying is, they are not going

to get re-infected, because they

have immunity?

But are you sure that's

true from these tests

that we're currently talking

about primarily?



VINCENT RACANIELLO: Well,

if, by immunity --

I mean, it's a -- it's a word

that can mean two things.

It could mean --

it can mean any antibody

or any immune response

against the pathogen

versus protection.

So notice, they're not

certificates of protection.



JOHN WHYTE: Yes.



VINCENT RACANIELLO: They're just

immunity.

Although, in some people's minds

--



JOHN WHYTE: That's what people

are assuming.



VINCENT RACANIELLO: Yeah, I

agree.



JOHN WHYTE: [INAUDIBLE]



VINCENT RACANIELLO: But I --

I don't think you can say

that you're immune.

Because you're not quantitating

how much antibody.

It's all or none, right?

And some people are going

to have very low amounts.

They may not be protected.



JOHN WHYTE: Should we really

be doing, then, a serum test

to get that quantitative amount

to know for sure?

Let's assume you had

unlimited resources.

What test, Vince, would you

do to tell us that you're

immune from getting re-infected?



VINCENT RACANIELLO: Oh, I would

take a tube of blood from you,

from your arm vein, first of all

-- not just a little bit.

And then you bring that

to a clinical lab.

And then you

do a quantitative test, where

you make dilutions of serum

against a fixed amount of virus

protein.

And you can tell exactly

what levels of antibody

you have.

And if you even wanted to do

better, if you wanted to know

protection, you would have

to know

about neutralizing antibodies,

right?



JOHN WHYTE: Sure.



VINCENT RACANIELLO: [INAUDIBLE]



JOHN WHYTE: So why can't we

do that?

Is it just resource intensity?

How are we going to do 300

million tests?



VINCENT RACANIELLO: Yeah, we --

we can't do that, right?

We can barely do 300 million

rapid tests.

That's why we're doing

the rapid test, because we can

do them quickly and they'll give

us an idea.

But they're not definitive

in terms of protection,

by any means.



JOHN WHYTE: But are we then

taking time away

from the diagnostic tests,

right?

Don't we still want to rapidly

build that up?

We're roughly only over 2

million diagnostic tests.

How are we going to do millions

of diagnostic tests,

and now we're going to ramp up

millions of antibody tests?



VINCENT RACANIELLO: Well, I

think that these "point of care"

tests

are not going to tax

the clinical laboratory capacity

of the US.

And I think, at the same time,

they need to be developing

the quantitative assays.

And we should start ramping that

up.

I'm hoping that's happening

behind the scenes, you know,

and they're not --

we're not being told about it.

But that absolutely has to be

done at the same time, for sure.



JOHN WHYTE: And what

about this issue

of reactivation?

We talked about that

on a previous interview.

Some people are saying that they

recovered.

Uh, and then they tested

positive again.



There's even some people that

are saying this is like herpes,

a DNA virus,

instead of an RNA virus.

What's going on here

with reactivation?

Could they have been immune

and then get the infection

again?



JOHN WHYTE: I don't think so.

I think what happened is they,

uh, recovered, and then

the tests --

you know, the tests that were

done -- the diagnostic tests

were wrong.

And so then, at some later time,

they tested them again,

and they saw they were positive

again.



But I don't think,

at that point, they're actually

shedding virus.

They're probably shedding pieces

of nucleic acid.

And so I'm not worried that this

is, uh, a persistent virus --



JOHN WHYTE: Mm-hmm.



VINCENT RACANIELLO: --

that's going to come and go over

and over.

This is a virus that gets you,

you get immune.

And then later, if you get

another infection,

it's going to be much milder.

So I'm -- I don't put much stock

into those reports.



JOHN WHYTE: So you do believe

that, once infected, you likely

develop some immunity

to COVID-19.



VINCENT RACANIELLO: Absolutely,

some immunity.

And if you are re-infected

at a later date -- let's say,

in the winter, when the virus is

coming back --

you might not even know it.

You could get a mild disease

with few symptoms,

because your immune response is

protecting you.



JOHN WHYTE: So you think you're

protected.



VINCENT RACANIELLO: Yes.



JOHN WHYTE: So do we need

the quantitative tests?



VINCENT RACANIELLO: I think

the quantitative tests, at least

initially,

would give us an idea

of whether the rapid tests are

telling us about just

general immunity or protection.

So it's kind of a research

question.

Can we depend

on the rapid tests,

and so, in parallel,

we should do

rapid and quantitative,

and say, oh, yeah, everyone that

has a rapid positive

is protected?

That would be great information

to have.



JOHN WHYTE: So we have these

point of care tests, which are

the pinpricks --



VINCENT RACANIELLO: Mm-hmm.



JOHN WHYTE: -- for which we have

perhaps greater capacity.

And then that quantitative test

is, we would do a lipid, or, you

know,

a CBC, or anything like that.



VINCENT RACANIELLO: That's

right.



JOHN WHYTE: How concerned do you

get when --

the public often --

we don't often understand

that tests aren't 100%.



VINCENT RACANIELLO: Mm-hmm.



JOHN WHYTE: And folks tend

to believe the test result,

whether it's a diagnostic test,

whether or not you have

coronavirus, or whether or not

you have antibodies.

What -- what are your thoughts

on how we educate folks more

about, tests aren't 100%,

and, sometimes, you have to go

back the old-fashioned way,

to symptoms and ruling things

in or out?



VINCENT RACANIELLO: Well, you're

right about tests.

And often,

in a clinical setting,

as you well know,

when a physician sees a test,

and it doesn't look quite right,

what do you do?

You do it again.

And usually, it's not going

to be wrong twice in a row.

And so if someone has had

symptoms of COVID-19 --

they had a diagnostic test which

said they were infected --

-- if you now do a -- a rapid

antigen or antibody test,

and it's negative, then you

should do it again.

Because if that person was

infected, they should have

an immune response.

So I think that's really

important, especially

at this early date, when, as you

said, a lot of the tests

are not quite fully baked yet,

right?



JOHN WHYTE: Yeah.

Mm-hmm.

Now, I don't have a wand.

But if I did, and I made you

the immunology czar --



VINCENT RACANIELLO: Mm-hmm.



JOHN WHYTE: -- what do we have

to do over the next week or two

to get to where you think we

need to be to start thinking

about opening up the country

a month, two months from now --

whatever that time may be?



VINCENT RACANIELLO: So I think

what we need to do is what

many people are talking about.

Start testing as many people

as possible for antibodies

to the virus, to SARS-CoV-2.

And at the same time, a fraction

of those should be compared

in -- in a clinical lab test --

quantitative antibody tests,

to see if the rapid tests are

giving us the right information.



JOHN WHYTE: What

about diagnostic testing though?



VINCENT RACANIELLO: So --



JOHN WHYTE: Where does that go?



VINCENT RACANIELLO: So to these

people who are infected and have

had symptoms --

so we have two sets.

We have -- some people are

in hospital.

And they've obviously had

diagnostic tests to show

that they're positive.

And then there are others who

are not.

And maybe they have had

symptoms.

They're never going to have

a diagnostic test,

because their infection is over.

But now, we ask,

do you have antibodies?

We would like to know,

in the general population, what

fraction of people

have antibodies to the virus,

not just by a rapid test,

but-- but spot-checking some

of those

with quantitative tests?



JOHN WHYTE: Why does that help?

Why does that help you?

Why do you need

that information?



VINCENT RACANIELLO:

The quantitative tests?



JOHN WHYTE: No, even just what

percentage of people

of in the population

have antibodies.



VINCENT RACANIELLO: Because we

know, with this virus,

somewhere between 50% to 70%

of the population being immune

will stop spread of infection.

So if you have a city somewhere

in the US,

and you find that half

of the population

is antibody-positive,

they can probably resume

their normal lives

at this point.



JOHN WHYTE: And then how long

do you have to wait

after symptoms

to take an antibody test?

You shouldn't take it

while you're having symptoms,

correct?

So how long?

Is it a week, two weeks?

Does it matter?



VINCENT RACANIELLO: So if if you

have onset of symptoms with this

virus -- remember,

the incubation period can vary

from one to 14 days.

And usually, we say the antibody

response kicks in a week or two

after the virus starts

to multiply in you.

So I would say a week or two

after symptom onset is probably

the safest time to start doing

the antibody tests.



JOHN WHYTE: All right.

Well, that is great information.

We'll see what happens

with our capacity

over the next few weeks.

And perhaps we can have you back

to critique how well we're

doing.



VINCENT RACANIELLO: That would

be great.

Love to do it, John.

JOHN WHYTE: Dr. Racaniello, I

want to thank you again

for taking time to spend

with us.



VINCENT RACANIELLO: My pleasure.

JOHN WHYTE: Thanks for watching

Coronavirus in Context.

I'm Dr. John Whyte.



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Vincent Racaniello, PhD. Professor of Microbiology & Immunology, Columbia University. John Whyte, MD, MPH. Chief Medical Officer, WebMD./delivery/aws/62/ee/62eed49c-2615-3297-aba1-638810968c55/091e9c5e81ebe221_coronavirus-in-context-racaniello-antibodies_,4500k,2500k,1000k,750k,400k,.mp404/14/2020 12:00:0018001200photo of Vincent Racaniello/webmd/consumer_assets/site_images/article_thumbnails/video/coronavirus_in_context_racaniello_antibodies_video/1800x1200_coronavirus_in_context_racaniello_antibodies_video.jpg091e9c5e81ebe221

Hoping to discover just how widespread the virus has become, last week the National Institutes of Health (NIH) announced they’re looking for 10,000 volunteers with no confirmed history or current symptoms of COVID-19. Researchers want to see how many have antibodies in their blood.

“We don’t currently have good numbers for the numbers of people who are infected now, much less people who were infected before who were never tested,” Angela Rasmussen, MD, a virologist at Columbia University in New York, told The New York Times. “So it’s really important from an epidemiological perspective to do these types of serology assays.”

The NIH is far from the only organization working on this. In March, the FDA announced a policy that would allow commercial labs meeting certain conditions to market their tests without waiting for the FDA approval known as an Emergency Use Authorization (EUA). More than 70 of those tests are on the horizon. Only one test has received an EUA.

“Within a period of a week or so, we're going to have a rather large number of tests that are available,” Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases, recently told CNN.

But experts warn that the presence of antibodies alone doesn’t necessarily indicate you’re cleared to reenter the world. First of all, there are several types of antibodies. Only a subset known as neutralizing antibodies can block the virus.

“We don’t know which antibody response neutralizes the virus,” says Joseph Vinetz, MD, a professor of infectious diseases at Yale University. “Once you have an antibody test, you have to study people with antibody responses for their risk for getting a new infection.”

That won’t happen, he says, until enough people who test positive for antibodies return to the workforce -- and then either get reinfected or don’t. It’s a waiting game.

“If the governor of a state says, ‘We have an antibody test, I can release people back to work,’ the data don’t really support that at this point,” Vinetz says. “We’ll find out what happens when policy gets balanced against science.”

Then there’s the magnitude of the challenge of testing everybody. With more than 300 million people in the U.S., the 3 million diagnostic tests performed to date represent barely 1% percent of the population. On Saturday, Admiral Brett Giroir, the testing “czar” on Trump’s coronavirus task force, told Bloomberg News that by May the country should be “in the ballpark” of capacity for widespread diagnostic and antibody testing.

Unreliable tests may pose another problem. In the U.K., Spain, and elsewhere, false test results have dashed hopes for a quick, accurate test. And in the U.S., the FDA’s decision to relax oversight for antibody tests may backfire.

“It really has created a mess that’s going to take a while to clean up," Eric Blank, DrPH, senior director at the Association for Public Health Laboratories, told ABC News. "In the meantime, you’ve got a lot of companies marketing a lot of stuff and nobody has any idea of how good it is.”

For now, at least, no test can tell you if you’re safe to go back to your regular daily life. No testing company has made enough tests to garner large-scale results. And though you may see tests claiming otherwise, none has been specifically approved by the FDA.

“If you see [tests] on the internet, do not buy them until we can give you a test that’s reliable for all Americans,” Deborah Birx, MD, coordinator of the White House coronavirus task force, said at a recent briefing.

Given all the uncertainty surrounding antibody tests, “what we really need is a pill that reduces the amount of time that somebody is ill or infectious for other people, or that might prevent people from getting infected to begin with,” Vinetz says. The Yale School of Medicine, where he works, and Yale New Haven Health System are working on that. They’re establishing a drive-through COVID-19 clinical research platform for patients with mild or asymptomatic cases, which Vinetz hopes will open in the next few weeks. Those who test positive will be given either an experimental antiviral drug or a placebo, then asked to return for daily swabs for 1 week to check the amount of the virus in their throats, with weekly monitoring after that.

Vinetz anticipates having preliminary results within 2 weeks of the platform launching.

“Right now, people can have this virus for a couple of weeks,” Vinetz says. “What if you were only infectious for 2 days? If a drug really kills the virus, not only can you treat people who have the infection, if the drug is safe, you can give it to people as prophylaxis.”

WebMD Health News Medically Reviewed by Michael W. Smith, MD on April 13, 2020

Sources

CNN: “Nearly 91% of Americans have been ordered to stay at home,” “Fauci says antibody tests will be available in the US within ‘a week or so.’”

New York Times: “Torn Over Reopening Economy, Trump Says He Faces ‘Biggest Decision I’ve Ever Had to Make,’” “Will an Antibody Test Allow Us to Go Back to School or Work?”

Joseph Vinetz, MD, FACP, FIDSA, FASTMH, professor, Section of Infectious Diseases, Yale University.

Johns Hopkins University: “COVID-19 Dashboard by the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University (JHU).”

Bloomberg News: “U.S. Testing Capacity in ‘Ballpark’ for May Reopening, Czar Says,” “New Test Hopes Dashed as U.K. Finds Antibody Kits Don’t Deliver.”

ABC News: “Fears of 'Wild West' as COVID-19 blood tests hit the market.”

National Institute of Allergy and Infectious Diseases: "NIH Begins Study to Quantify Undetected Cases of Coronavirus Infection."

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