In these acute-crisis moments, no one can definitively put anything off the table, of course, lest one be later accused of overlooking an effective strategy. When CNN’s Alisyn Camerota asked Anthony Fauci this morning about immunity certificates, he seemed reluctant to even address the idea, although he warms up a bit to the notion eventually:

Dr. Anthony Fauci, a key member of President Trump’s coronavirus task force, said Friday that certificates of immunity for Americans have been discussed during White House meetings, according to a report.

Fauci, head of the National Institute of Allergy and Infectious Diseases, said on CNN that the idea that people carry such certificates to prove they have tested positive for antibodies might “have some merit under certain circumstances.”

“It’s one of those things that we talk about when we want to make sure that we know who the vulnerable people are and not,” Fauci said, adding that the antibody tests will be available soon.

It’s one of those things we talk about, but likely never do. That’s not to say that some countries haven’t tried it — China’s using smartphone apps to ID coronavirus survivors, and Germany’s testing it out. The problems start with the idea of immunity itself, which may not actually be possible at all. South Korea now reports that some who survived their first bout of COVID-19 are seeing “reactivation” of the virus, although whether they will be as sick or not remains to be seen. They will at least be somewhat contagious if relapses can occur afterward.

This point came up in today’s briefing, and it didn’t sound promising for immunity certificates:

Important. Trump (backed up by Fauci) says "we don't know yet" how long someone who gets over COVID19 retains immunity. Lots of ramifications.

— Olivier Knox (@OKnox) April 10, 2020

Furthermore, the usefulness of such certificates depends on reliable and widespread testing, even if full and permanent immunity can be acquired without a vaccine or treatment. Fauci sounds very optimistic that we are just days away from widespread testing capabilities not just for viral infection but also for effective antibody levels, too. That would be great news on its own for other reasons, but do we know that they will be accurate enough to issue reliable Get Out Of COVID Jail cards? The FDA is waiving some of its certification requirements in the interest of haste, which at least opens the possibility that these tests might not be reliable enough for this purpose. We might end up encouraging people to circulate that have COVID-19 and give everyone else around them a false sense of security, at least for the first few months of such a regime.

Speaking of which, what would be the use of such certificates? The better path would be to keep social-distancing policies in place even when reopening businesses. Would certificate holders be exempted from those regimes, and would they want to be?

Remember too that a vaccine might not provide permanent immunity. Even for diseases that don’t have a constantly mutating virus (like influenza), some vaccines require regular boosters. We won’t know the parameters of that issue for years after finding a vaccine, which is still months away.

So those are a couple of the problems with “immunity” certificates. This, um, is another:

There will be a giant orgy the day people get their govt-issued "COVID-19 Antibody ID Cards."
And I'll be right there, selling bootleg cards.

— Joe DeVito (@JoeDeVitoComedy) April 10, 2020

Joe DeVito means this as a joke, but it’s a serious point. The more benefit that accrues to such a certificate, the more incentives come into play to bootleg or forge them. Orgies aren’t the only draw; who wants to eat in a restaurant, for instance, or see a movie in the cinema? Go to a play on Broadway? Attend a Stones concert? If the COVID Card is the prerequisite, we can expect a non-zero number of people to find ways around it.

It’s unworkable. Hopefully the people whose jobs it is to mull things over will apply their mulling energies to more useful ideas.