By Kelly Yamanouchi, The Atlanta Journal-Constitution

Troy Warren for CNT

International travel destinations are opening up again as the summer travel season shifts into higher gear — but not without hurdles or headaches.

Delta Air Lines is ramping up its schedule of routes to Europe, including starting flights from Atlanta to Athens, Venice, Barcelona and Madrid starting in July and August.

Most foreign carriers have restarted flights from Atlanta, including Qatar Airways and Lufthansa relaunching service earlier this month. Mexico and much of the Caribbean have been welcoming tourists for months.

Tourism is still heavily restricted in much of Asia, though. Same for Canada, the United Kingdom and many other destinations.

Would-be international travelers from Atlanta also have to navigate a confusing, constantly shifting maze of restrictions as governments around the world try to gauge the spread of COVID-19 variants and whether visitors have been vaccinated.

Countries are reopening, “but it’s not something that’s black and white. It’s a very fluid situation,” said Claire Murdock, a travel specialist at AAA.

There could be one requirement in place today, but “it might change tomorrow,” she said, adding it’s never been more challenging in her 25 years in the industry.

By April, international flights at Atlanta’s Hartsfield-Jackson had recovered to nearly 50% of 2019 levels, compared with a 95% plunge a year earlier. But the volume of international passengers was still down nearly 75% this spring.

Some countries that have reopened require negative COVID-19 tests to be exempt from quarantines. But the timing of the tests varies — it could be 24, 48 or 72 hours before arrival, depending on the destination. Some countries exempt travelers who are vaccinated, while other countries don’t.

Then there’s the risk of testing positive before returning — and being stuck in a foreign country, unable to fly back home due to U.S. entry restrictions.

European countries with economies that depend heavily on tourism were among the first to reopen their borders — including Italy, Greece, Spain, Portugal and France.

The European Union on June 18 encouraged other member countries to reopen, putting the United States on its list of countries for which travel restrictions should be lifted. The Netherlands on Thursday became the latest to lift its ban on American tourists.

But each of the EU’s 27 member countries has the final say on whether to reopen — and what rules it wants in place.

Germany lifted restrictions on travel from the U.S. on June 20. This week, though, Chancellor Angela Merkel raised concerns about the delta variant, saying Europe is “on thin ice” and pushed for unified quarantine requirements for travelers from countries where the variant is prevalent, according to news reports.

At present, you can fly to Germany without getting tested for COVID-19 if you bring proof of vaccination that complies with German requirements. But in order to fly back home to the United States you must present a negative test taken during the trip.

Travel industry officials have lobbied for the lifting of travel restrictions between the U.S. and the U.K., a key travel corridor for corporate travel in particular. But U.K. Prime Minister Boris Johnson recently extended lockdown rules due to the delta variant. The U.K. requires travelers from the U.S., currently on a list of “amber” or moderate risk countries, to self-quarantine for at least 10 days, or five days with pre-booked COVID-19 testing.

China requires quarantining upon arrival, Korea also has certain quarantine requirements and Japan has an entry ban in place. In South America, Brazil requires COVID-19 tests to enter the country, while Argentina is restricting entry.

Delta recently announced a shift in plans to relaunch a route to South Africa, opting to resume service from Atlanta to Johannesburg on Aug. 1 instead of a “triangle route” including Cape Town.

The reason: South Africa’s government would not approve Delta’s request to stop in Cape Town. In turn, the U.S. Department of Transportation denied the renewal of some South African Airways flight authorizations.

Some travelers have been barred from boarding cross-border flights because they don’t have the correct COVID-19 test to fulfill a particular country’s requirements. Updates to travel restrictions are so frequent that an EU website on the reopening is relying partly on automated translation.

“It’s not enough to say you can travel again. Travelers have to be confident in doing so,” said Mike McCormick, co-founder of a travel industry coalition advocating for the reopening of borders and common standards for digital health certificates.

Airlines and other travel companies have developed extensive collections of maps with travel restriction information and links to different countries’ websites — all aimed at making it easier for travelers to navigate through different documents and rules, then stay on top of any changes until the time of their trip.

Delta, the dominant carrier at Atlanta’s airport, sells passengers COVID-19 test kits they can take with them on trips to get results for their return flight home. Delta also has developed a system for digital health credentials which can verify test results.

With health credential verification a new part of the check-in process, AAA’s Murdock said travelers should get to the airport three hours before an international flight.