(CNN) — The 2021 summer travel season started out full of hope and promise, but increasingly by the week, the Delta variant is throwing it in disarray.
This more transmissible variation of the coronavirus was first detected in India in February, just when the United States and some other places around the world were starting to gear up their vaccination efforts. It turned out to be a race against time: shots in arms vs. Delta's spread.
Delta infections are climbing as we enter August, particularly among the unvaccinated. Just like all other waves of the pandemic, travel feels the Covid impact quick and hard.
From the latest travel news to recent Google searches on the topic in the past few days, it's clear the Delta variant is causing increasing worry and disruptions for governments and would-be travelers. Here's a quick round-up:
UK green list update
The entire world seems to have the United Kingdom on its collective hive mind. In the past 24 hours, worldwide searches for various terms surrounding the United Kingdom's "green list" have risen anywhere from 450% to 200%.
The official announcement is to come Thursday, August 5, that Austria, Germany, Latvia, Norway Romania, Slovakia and Slovenia will be added to the green list.
A traffic light-based travel system -- red, amber and green -- is in place in England, Scotland, Wales and Northern Ireland. Non-UK residents from red list countries are currently refused entry to the UK. British residents arriving home from red list destinations must undergo a 10-day hotel quarantine at their own expense.
You can read England's list here. Northern Ireland, Scotland and Wales have their own rules but tend to follow suit. You can click links on the England site to see the latest from those places.
Mexico wants to know about a neighbor
A butterfly hatches from its pupa at the National Museum of Costa Rica.
Juan Carlos Ulate/Reuters
Meanwhile, Mexicans are more interested in travel restrictions to Costa Rica, a favorite of tourists in Central America.
The is one nation not yet putting up any barriers because of Delta: As of August 4, tourists from any country can still visit and arrive via air, land or sea (but only on yachts and sailboats in specific ports). There aren't even any Covid-19 tests or quarantines in place. But you are still required to fill out a health pass.
New York City: Get vaccinated for the full experience
People walk and ride bicycles over the Brooklyn Bridge earlier this year. Vaccine mandates are going to be set up for indoor venues in New York City.
Ed Jones/AFP/Getty Images
New York City, on the other hand, is responding to rising cases of the Delta variant in the United States. It's keeping out the welcome mat to tourists, but they'll find more rules to follow soon.
Mayor Bill de Blasio announced August 3 that vaccines will be mandated for employees and patrons of New York's indoor dining, fitness and entertainment venues.
The "Key to NYC pass" will launch August 16 and begin being enforced September 13, he said. Final details of the program are expected to be announced the week of August 16.
Chicago responds to the Delta variant
While the state of Illinois has no travel restrictions, the city of Chicago does.
Chicago has a separate system that advises Covid-19 testing or quarantine if the unvaccinated visitor comes from a state with a significant infection rate.
As of August 3, there were 19 states and two US territories on the "orange list" that asks for testing or quarantine. Some of the states falling into the orange category included Georgia, Florida, Texas and Missouri.
China cracks down again
Visits to the wildly popular Great Wall may have to be postponed again.
NOEL CELIS/AFP/AFP via Getty Images
Your dreams of seeing the Great Wall and other sites of China soon will most likely have to be postponed.
Because of the Delta variant, China is grappling with its worst Covid-19 outbreak in months. The country now has 144 medium- and high-risk areas, the most since the initial outbreak in early 2020, the National Health Commission said Wednesday.
Chinese immigration authorities have vowed to "strictly restrict non-urgent, unnecessary cross-border travel," including tightening the issuing of passports for Chinese citizens.
The speed and scale of the spread has also spurred mass domestic travel restrictions, with all inter-city coach, taxi and online car hailing services suspended in medium- and high-risk areas.
More destinations moved to Level 4 this week
The Acropolis in Athens, Greece, during sunrise. Greece was moved to the CDC's "Level 4" warning, its highest, on Monday.
Ludovic Marin/AFP/Getty Images
Other popular destinations that were already on Level 4 before Monday's announcement included Brazil, the Maldives, Portugal, Spain and the United Arab Emirates.
Highlights from the previous week
"We will maintain existing travel restrictions at this point for a few reasons. The more transmissible Delta variant is spreading both here and around the world," Psaki told reporters. "Driven by the Delta variant, cases are rising here at home, particularly among those who are unvaccinated and appear likely to continue in the weeks ahead."
People who have been in Brazil, China, the European Schengen Area, Iran, India, Ireland, South Africa and the United Kingdom in the past 14 days are denied entry to the United States. -- Search interest in Mexico: Google searches for this popular destination have been high. Mexico has been -- and continues to be -- one of the easiest countries to visit. Its land border with the United States has been closed for well more than a year now, but air traffic has been flowing in from all over the world. You don't even have to provide a negative PCR test result or quarantine on arrival. Mexico was at "Level 3: High" on the CDC's advisory list.