The COVID-19 vaccine passport debate kicked up again on Twitter this week after former Libertarian Rep. Justin Amash of Michigan posted a now-viral tweet opposing the idea. "No vaccine passport," Amash wrote. "It doesn't get much more dystopian than being required to show your 'health papers' wherever you go."

We've had this conversation before. I wrote about it almost exactly a year ago, when COVID-19 vaccines were still a distant hope and the proposal at hand was immunity passports for those who'd had the disease, built antibodies, and recovered. Though I absolutely feel the appeal of a passport system — I'm all for vaccinations and eager to to get back to normal life — I have the same objections now as then, which I'll revisit in a moment. But the more interesting question, perhaps, is why the passport idea has resurfaced now. I think it's because we need a pandemic endgame scenario, and we don't have one. Passports offer an endgame, true, but it's not the endgame we need. They're a bad hack of normalcy with a real risk of unintended, detrimental consequences.

The introduction of vaccines (instead of antibody testing-determined immunity) defeats one of my previous criticisms of the passport plan. We can know whether someone's gotten their shots more simply and reliably than we can determine their natural immunity. Still, the problems with this present iteration aren't terribly different from those I discussed last April.

One enormous issue is privacy and, relatedly, enforcement. The vision of vaccine passports, as Amash distinguished, is state-mandated "proof of vaccination for everyday living," not for unusual occasions like international travel or locations (like schools) where you can provide one-time proof because there's an established relationship. How will this everyday proof scheme be enforced? Are we saying "papers, please" at the Target door? Are police involved? Is refusal to participate criminalized? (What will we do when the first video of a cop beating an unarmed Black man for declining to produce a vaccine passport goes viral?) What about people who can't be vaccinated? Do they have to share their medical status with every grocery store they visit? Is there a centralized database of who's vaccinated and who's not?

That brings us to another problem: data security. A centralized list would be risky, attractive to hackers, and ripe for state misuse. (The history of abuse of other public safety measures, like the post-9/11 Patriot Act, is instructive here.) Amash clarified that his position is linked to a broader worry about "a future in which people are constantly required to prove their 'worth' through health or genetics or other discriminatory criteria." That's a legitimate concern in a world which combines bigotry and big data.

Fraud would be an issue, too. COVID-19 vaccine hesitancy is dropping, thankfully, but dedicated vaccination opponents would undoubtedly forge passports. (In fact, a passport system might well exacerbate their hesitancy by "confirming" conspiracy theory fears.) If they fail, maybe we've just expanded mass incarceration. If they succeed, the immunologically vulnerable could be lulled into false security.

So I think Amash is right we shouldn't go the passport route. But if not passports, what? "If you don't let people prove they've been vaccinated, businesses and government will have to treat everyone as though they're unvaccinated," Slate's Will Saletan replied to Amash. "That could mean persistent social distancing rules, capacity limits, masks, etc. That's a net loss of freedom." This is exactly the allure: Vaccine passports offer a ticket back to normalcy. If we reject it, what's our alternative? What's the endgame? When will it stop?

The endgame I believe we need is this: At a certain chronological distance from the point at which vaccines are easily available to all adults in a given city or state, we go back to normal life. By "easily available" I intend the plain meaning of the words: Any adult medically eligible for a vaccine can get an appointment on request at a time reasonably convenient for them. I don't think we've reached this point anywhere in the U.S. as of this writing, but with vaccine distribution accelerating, some places may reach it as soon as the end of April.

By "normal life," I also intend the plain meaning: no government mask mandates (private homes, businesses, etc. can do as they like). No government-enforced social distancing or lockdowns (again, private caution is always permissible). No school closures.

And as for the chronological distance, I suggest six weeks — long enough for all who want them to get both shots and develop immunity — but this is a decision that public health experts should inform. Maybe six weeks is too careful or too brief.

I realize this is not the endgame commonly envisioned. More often we hear about hitting a certain level of adult vaccination. Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, is pushing for 85 percent.

We may hit that goal because, again, vaccine hesitancy is way down. Per The Wall Street Journal's latest numbers, just 17 percent of Americans now say they maybe or definitely won't get a COVID-19 shot. Expert estimates of the herd immunity rate go as low as 50 percent, which would make 17 percent refusal functionally irrelevant. "In our models," said a recent analysis from investment bank JPMorgan, "the number of anti-vaxxers is too small to materially change the timing of the pandemic's end." I've worried (at length) about vaccine refusal, but I'm increasingly optimistic we'll shortly reach a scenario where adamant refusers are too few to significantly endanger others.

But what if we don't hit Fauci's goal? This is the trouble with pinning normalcy to a vaccination rate instead of vaccination availability. Are we really going to let a small minority of refusers hold the rest of us hostage? Are we going to keep wearing masks, missing family, doing Zoom church, canceling parties because a few obstinate folks aren't availing themselves of this triumph of scientific ingenuity? Even though every vaccine on offer in the U.S. has proven remarkably effective at preventing hospitalizations and deaths from COVID-19? That's absurd. Vaccine refusers should not be legally coerced into putting something they don't want inside their bodies, but neither should they be given such power over the lives of everyone else.

At some point — say, six weeks after vaccines are easily available to all adults in a given city or state — we have to say: On your own head be it. Suffer the consequences you have chosen by refusing the vaccines. The rest of us are acceptably protected from this illness, and we're moving on.