Analyzing Antibodies: Dr. Sanjay Gupta's coronavirus podcast for April 15

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Dr. Gupta: As coronavirus cases in some US hotspots begin to peak, focus is shifting to what measures are necessary for the country to start reopening.

In addition to diagnostic testing and tracing the spread of infections, one major factor in planning will be knowing who has recovered from the coronavirus and may have some immunity.

Since so many people who've gotten infected haven't displayed any symptoms, it's hard to know who might be immune. The way we could find out is by testing people for antibodies.

So, in this episode I'll explain exactly what antibodies are and how they could help the country get back on its feet.

I'm Dr. Sanjay Gupta, CNN's Chief Medical Correspondent. And this is "Coronavirus: Fact vs. Fiction."

Tony Huston: I think it's human nature to want to know if you've had it or if you have the antibodies.

Dr. Gupta: That's Tony Huston, who got tested for Covid-19 antibodies in San Jose, California, earlier this month. We'll come back to him later.

So, what are antibodies?

Antibodies are proteins in the immune system that are created soon after an infection. They can be identified with a quick blood test -- also called a serology test. It won't tell you whether the virus is currently active in your body, just whether it has ever been active in your body. This is key, because so many people who have had Covid-19, have not displayed any symptoms.

We don't know for sure whether having had the virus gives you immunity against it, but health experts do suspect that's the case.

Last week, White House Coronavirus Task Force member Dr. Anthony Fauci told CNN that a test is coming soon.

Dr. Anthony Fauci (April 10): I'm certain that, that's gonna happen. That within a period of a week or so we're going to have a rather large number of tests that are available.

Dr. Gupta: So, what is the test?

Compared to the Covid-19 diagnosis test -- which is an invasive nose swab typically -- this test is pretty simple. It's just a finger prick to draw a small blood sample. That blood sample is then put on a test strip that contains proteins from the virus. So, if your blood reacts to the strip, it means you have antibodies.

And why does antibody testing matter?

Well, there are several reasons it's important to know who has antibodies against Covid-19 and might be immune to it. Besides peace of mind, of course.

Those who test positive for antibodies can likely resume their normal lives -- go back to work, visit friends -- without fear of infecting others or getting sick again.

This might especially be helpful for healthcare workers and essential workers who could do their important jobs without worrying.

Widespread antibody testing would also give us a better sense of exactly where the virus is. It could be true that a significant number of people have had Covid-19 without realizing it.

Director of the Centers for Disease Control and Prevention Dr. Robert Redfield addressed this on NBC's "The Today Show."

CDC Director Robert Redfield (April 13): Antibody testing's going to give us a good idea from a surveillance point of view of- of how significant the outbreak was. And in certain circumstances I think it will help bring consumer confidence in certain workforces.

Dr. Gupta: So, the benefits of antibody testing are clear. But how soon could any of us actually reap those benefits?

As of this recording, only one Covid-19 antibody test has emergency use authorization by the Food and Drug Administration.

So be aware of bad antibody tests being offered online. They might give you false results.

FDA Commissioner Stephen Hahn was asked about this on NBC's "Meet the Press."

FDA Commissioner Stephen Hahn (April 12): What we don't want are wildly inaccurate tests because that's going to be much worse -- having a wildly inaccurate test -- than having no test.

Dr. Gupta: Despite that risk, some places are starting to test people anyway.

Santa Clara County in California, Miami-Dade County in Florida, and Telluride, Colorado, are a few places now conducting antibody tests. And the National Institutes of Health are recruiting up to 10,000 volunteers for antibody testing as well.

Tony Huston, who we heard from at the beginning, was able to register to get tested for antibodies in Santa Clara County. We spoke to him about his experience.

Huston: They had about five different tents set up and you just kind of drove through and they pricked your finger, took a blood sample and took down your information. I've recently contacted them to find out when we're going to get the results. I think they're hoping to get those done and out to everybody by the end of this week.

Dr. Gupta: Huston said he never got tested for Covid-19 but he was really sick back in January with several of the common symptoms of the disease. He said part of the reason he wanted to get tested for antibodies was to help researchers find out whether the coronavirus could have arrived in the United States sooner than they realized.

Plus, he has some underlying conditions like heart disease and diabetes.

Huston: I think in some ways it would actually be a relief to know if I did have it prior. Then I don't think I would necessarily feel like I have to be as cautious as I guess I am being right now.

Dr. Gupta: Knowing who has antibodies against Covid-19 could also speed up the search for a cure.

At last week's CNN Town Hall, my colleague Anderson Cooper and I spoke to a recovered coronavirus patient whose plasma is now being used to treat current patients. Here's Jason Garcia.

Jason Garcia: They take the blood, it goes through a machine, they separate it out, and they put the blood back in. And they just collect the plasma which has the antibodies. If you're donating blood or have donated blood before it's as simple as that and you could possibly save a life and help.

Dr. Gupta: The process is called convalescent plasma. To help the most people, convalescent plasma would require mass testing to find out who has the necessary antibodies against Covid-19.

Dr. Gupta: I want to reiterate that having had Covid-19 once does not definitively mean you are immune. Even if being infected once does give you some amount of immunity, health experts aren't sure how long that will last or how strong it will be.

They are hopeful that antibody testing is one thing that could help get the country back on its feet, but it would have to go hand-in-hand with more diagnostic testing for the virus itself, contact tracing, and increasing hospitals resources.

If you have questions, you can record them as a voice memo and email them to asksanjay@cnn.com -- we might include them in our next podcast.

We'll be back tomorrow. Thanks for listening.

You can also head to cnn.com/coronavirus and sign up for our daily newsletter, which features the latest updates on this fast-moving story from CNN journalists around the globe. 

For a full listing of episodes of "Coronavirus: Fact vs. Fiction," visit the podcast's page here.