A traveler shows up at an airline gate, claiming that she's been fully vaccinated against COVID-19 and thus can fly safely to a country that requires that visitors be inoculated.

How, exactly, can an airline — or hotel, or any number of other businesses that need to worry about the vaccination status of their customers — be sure?

Solving the problem is one of the key steps on the road to reopening the global economy. And as controversial as they've become, "vaccine credentials" that allow individuals to show they've been vaccinated should be part of the answer — as long as careful safeguards are included.

How, or if, to certify vaccinations has become a more pressing concern as more Americans get vaccinated against COVID-19. Uncertainty remains about whether and when the country will reach herd immunity.

Until then, the reality may be that Americans will have to learn how to travel, fully reopen the economy, and live with the virus before we're able to live without it.

Vaccine credentials developed and used by the private sector, with the help of forthcoming federal guidance, can serve as a way to help Americans and business navigate that tricky limbo period after hundreds of millions of Americans are vaccinated but before the pandemic is halted for good — so long as they do not serve as a de facto government mandate, and important protections are put in place to make sure they don't do more harm than good.

Disingenuous attempts to politicize the idea of "vaccine passports," similar to how masks were used as weapons in an ideological culture war, are already overshadowing the real causes for concern about them. No, there is no hypocrisy in opposing onerous ID laws for voting while also supporting a measure to help people demonstrate virus immunity when they need to, and actions like the executive order Gov. Ron DeSantis of Florida signed banning vaccine passports are counterproductive.

But a host of valid problems with the idea have been flagged by an ideologically diverse group of civil rights organizations, business groups and watchdogs. They fear that the use of vaccine passports could exacerbate inequities already revealed by the pandemic, lead to digital data breaches or fraud, or create a "show me your papers" mentality that could add fuel to existing culture wars. Others fear they may be bad for some small businesses that might struggle to meet their requirements.

The Biden administration has ruled out implementing a government-mandated vaccine passport system but is crafting guidance for the private sector. That guidance must address the concerns about access and data security with requirements that the certificates be issued in paper form, so even those without smartphones can have them — and so that personal information is not held in a central location and susceptible to hacking.