On this episode of Social Distance, staff writer Sarah Zhang joins Katherine Wells and James Hamblin to talk about the limits of antibody testing, whether we’ll be carrying around cards with our immunity status, and the lessons she’s learned from reporting on past epidemics.

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What follows is an edited and condensed transcript of their conversation.

Katherine Wells: Chile is starting to roll out a program to give people immunity passports. How widespread is this notion, and how close is it to being implemented in different countries?

Sarah Zhang: Chile has announced they’re going to do this, but there aren’t very many details. Germany has a scientist working on antibody tests that can tell us who is immune and who is not. The U.K. also floated this idea a few weeks ago. The health minister said people might wear immunity wristbands. Then it came out that the U.K. had bought 3.5 million antibody tests from China that turned out not to work.

There is maybe a little caution ahead as we jump into this new world of “immunity passports.” We don’t know how immunity works with this virus, and we don’t know how long it will last. Also, antibody tests can pick up false negatives and false positives. You may be sending people out there who think that they’re immune, but they’re not.

James Hamblin: That’s a pretty high-consequence decision, especially because we might be using these passports to say who should do essential work that could put them at high risk if they aren’t actually immune.

Zhang: Exactly. If we’re using these tests to decide whether to send people out to do their jobs, that’s a big decision to make based on tests that are really new.

Hamblin: My friend went to urgent care in Culver City in L.A. and got an antibody test for IgM and IgG antibodies. These different forms of antibodies appear at different time periods after you’re infected, and you can use them to understand how recently you were infected. If you just have IgM, doctors are telling patients that it means you’ve had recent exposure to the virus and are in the early stages of infection. If you have both positive, they’re saying you have a less-recent exposure and are in the middle of an infection. If you have only IgG positive, you had a past infection and have built some level of immunity. My friend has been told he has that.

Wells: So he has some level of immunity?

Hamblin: I would think yes, though there are false positives.

Zhang: Even a validated test will have some percentage of false positives, because all tests do. We’re at this point where you get an antibody test result and think you get certainty, but in reality you just get a little bit less certainty.

Wells: Are the problems with antibody tests solvable?

Zhang: As one scientist told me, antibody tests themselves aren’t rocket science. We have antibody tests for lots of other viruses. You can go to your doctor’s office now and get a measles antibody test, for example. I could see a world in which this becomes a routine thing that you get at your doctor’s office. But right now, it’s so early that it’s hard to tell what tests actually work.

Wells: When will we have a widespread antibody test, and an understanding of what those test results say about immunity?

Zhang: Getting a test that we know works is going to come a lot more quickly than getting a test that everyone can have. With the tests that detect COVID-19, we knew how to make those months ago. We’re still not at the point where everyone can get one. The hard part isn’t going to be making the antibody test itself; it’s going to be making sure everybody can access one.

Hamblin: A few weeks ago, we were talking about antibody testing as a theoretical possibility. Now they’re here. They’re not going to be immediately perfect, but if this disease does prove to work like lots of other viruses, we should be able to have a somewhat reliable test pretty widely available within months.

Wells: Say we have a widespread, accessible antibody test. How do we use that to get people participating in society again? Logistically, what does that look like?

Zhang: No one has quite figured that out. One of the unintended but almost obvious consequences is that if you make it so that only immune people can get a job, you incentivize people to get sick so they can work, especially since so many people have lost their jobs. If that’s the case, you could have people fake their immunity certificates.

Wells: It does seem like having a card that identifies your immunity and therefore allows you to participate in society could actually escalate an outbreak by perversely incentivizing people to get the virus. How has this been handled in past outbreaks?

Zhang: One analogue that I’ve been looking into is what happened with yellow fever in the 19th century in New Orleans. No one in 19th-century New Orleans really knew how immunity worked, but they noticed that newcomers to the city were the most likely to get sick. The word they used was acclimation. New migrants to the city would try to get sick right away because they could only get jobs once they were acclimated. People wouldn’t rent to you in a boarding house or let their daughters marry you or even give you a job unless you’d been acclimated. You had employers lamenting that they had just hired a new clerk and trained them and then they got yellow fever and died. They called it a “baptism of citizenship,” where you weren’t able to access society fully until you were immune.

Wells: Does this seem like it might be a reasonable path forward?

Zhang: Immunity creates a new division in society, and I’m nervous about what that will mean. We’re living in a time of profoundly high unemployment. Who are the people who are going to be able to work? That profound inequality, along with this new privilege, makes me nervous. Imagine you’re a food-delivery service and you, of course, only want to hire people who are not going to get sick. If you have someone sitting at home with rent coming up in a week who doesn’t know how to pay, they might think getting sick and recovering is the best way to get a job. There are already young people who think that they are invincible to the coronavirus. What if you see them trying to infect themselves so that they can have immunity and get that job, because employers only want to hire people who are immune?

Hamblin: Have you spoken to any experts who’ve laid out any sort of plan of what this could look like in an ethically possible way?

Zhang: To be honest, no. People are thinking about it, but we’re not at that point yet.

Wells: I keep hoping for solutions, and the solutions keep getting more complicated. One of the things I latched onto in my mind as a possible solution was antibody testing. It seems like not only is it logistically and scientifically far off, but it is an ethical and civil-rights minefield.

Zhang: Antibody testing is not the cure-all that’s going to open up society and make life normal again. It’s going to be really important for research, and it’s going to be really important for telling us how many people have actually had COVID-19. But the very early data we are getting is that not very many people have had it. Until you get to a point where lots and lots of people have had it, antibody testing is not going to get us back to a normal life.  

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