As of Wednesday, countries had distributed nearly 2.2 billion COVID-19 vaccine doses globally. Reported COVID-19 infections are falling in places with high vaccination rates, like the U.S., U.K., and Israel.

But borders are locked and in-bound quarantine rules remain in place around much of the globe, even though public health bodies like the U.S. Centers for Disease Control say that quarantine-free travel for fully vaccinated individuals poses few health risks for travelers and the destinations they visit. That’s not due to a lack of tools to facilitate travel for vaccinated people.

“It’s not technology that’s the missing piece,” Nick Careen, senior vice president of airport, passenger, cargo, and security at the International Air Transport Association, said Tuesday on a Fortune Global Tech Forum virtual conversation. Fifty-eight airlines are using IATA’s platform, which verifies COVID tests and vaccination records. “It is mutual recognition between countries that takes time,” Careen said. “And we hope it happens faster.”

Developing global vaccine passport standards has been a slow process. The World Health Organization (WHO) has mulled various proposals since last December under a Smart Vaccination Certificate working group. But after issuing initial draft recommendations in March, the WHO has not provided any concrete standards.

“We are not too far from block zero. I mean, that’s the reality,” said Fabio Vacirca, CEO of Accenture Asia Pacific, Middle East, and Africa. “Two-hundred governments is a very big number of potential agreements that need to be in place to mutually recognize [vaccine passports], whatever standards will be adopted.”

Jennifer Zhu Scott, executive chairman of the Commons Project, a digital services nonprofit that has developed a vaccine verification platform called Common Pass, agrees that the likelihood of all countries adopting a shared standard is low.

“Even with all the vaccines and fast [COVID-19] testing, we still rely on old methods [like quarantines] because country A can never trust country B,” she says.

Full resumption of global travel may be months—if not years—away, but pockets of international travel may restart soon.

Blocs like the European Union and the G7 are creating their own standards for recognizing vaccinated travelers, while China and Japan are developing stand-alone vaccine passport platforms and want to negotiate travel corridors with other nations on a bilateral basis.

“We’ve already seen travel in Europe…North America won’t be far behind, and [Asia] will probably be last, unfortunately,” said Careen. The U.S. and Europe are reopening their economies amid speedy vaccine rollouts, while some countries in Asia appear to be more cautious about unlocking their borders, he said.

Resumption of international travel may be further off for poor countries that are unable to secure vaccines. For now, a nation’s ability to procure and distribute vaccines remains closely tied to its wealth. WHO Director-General Tedros Adhanom Ghebreyesus said this week that high-income nations have gobbled up 44% of the world’s COVID-19 vaccine supplies, leaving just 0.4% of the vaccines for low-income countries.

“The vaccine distribution to the global south is particularly problematic,” says Zhu Scott. But she argues that rather than exacerbate inequalities, platforms like Common Pass can help normalize travel and other everyday activities until the world gets COVID-19 under control.

“We’ve built a digital infrastructure to enable people and our society to coexist with the pandemic before we can exit the global pandemic,” she said.