There is a lot to discourage travelers this summer: high prices, crowded tourist spots, fistfights on planes. Now they’re running into the highly transmissible delta variant, which is sending case numbers soaring and prompting new global restrictions.

The Centers for Disease Control and Prevention said last week that the variant — which was first detected in India — is responsible for more than 83 percent of cases in the United States, with the agency’s director calling it “more aggressive and much more transmissible” than earlier strains. It has spread to countries around the world, primarily threatening the unvaccinated.

According to Washington Post data, the number of new daily reported covid-19 cases in the United States increased more than 60 percent over the past week, while covid-related hospitalizations were up 38.5 percent.

What does the latest surge mean for people who are finally getting back on the road and in the air? Experts say they should prepare for shifting guidelines and restrictions, and do some homework about wherever they’re heading.

Expect more mask rules in U.S. cities

Savannah, Ga., and St. Louis reinstated indoor mask mandates even for vaccinated people Monday, following the lead of Los Angeles County earlier this month. The Post reported that other destinations are considering similar measures.

The CDC announced recommendations Tuesday afternoon that vaccinated Americans again mask up indoors in areas with high levels of infections.

International travel gets more complicated

To encourage vaccinations and prevent the spread of the virus, some European countries — which have finally reopened to Americans — are putting restrictions on what unvaccinated people can do.

In Greece, for example, indoor dining is restricted to vaccinated people only. France and Italy are requiring health passes that show proof of vaccination, documentation that you have immunity from infection or a recent negative test to take part in certain activities. And Malta is requiring unvaccinated visitors to quarantine.

“The landscape is going to remain very fluid,” said Robert Quigley, global medical director of medical and travel security firm International SOS. “We don’t know what’s going to happen tomorrow, we don’t know what’s going to happen next week in these European destinations which so many people are wanting to revisit.”

He said anyone traveling — especially internationally — should be getting up-to-date information daily from sources including the CDC, State Department and airlines.

The State Department and CDC issued upgraded warnings about traveling to destinations including Israel, Spain, Portugal and Britain in recent days.

For visitors who have been banned from coming to the United States, the delta variant is bad news. The White House said this week that travel restrictions against visitors from Britain, countries in Europe’s Schengen region and other nations would stay in place.

“The more transmissible delta variant is spreading both here and around the world,” White House press secretary Jen Psaki said. “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.”

Unvaccinated travel grows more dangerous

The CDC has already said people should not travel internationally and should delay domestic travel until they are fully vaccinated. But experts say that is especially crucial in light of the delta variant.

“Let’s say you’re unvaccinated: I think it would be probably not wise to travel, not just for your own safety because you may very well be more likely to be exposed in some of these other countries to the delta strain,” Quigley said. “But [also] because you may find when you get there, they say, ‘Where’s your vaccination proof?’ and [if] you don’t have it, they could throw you in quarantine.”

Families traveling with children too young to be vaccinated should craft their trips to protect the most vulnerable members, said Clare Rock, an infectious-disease physician and associate professor of medicine at Johns Hopkins School of Medicine. That would include eating and congregating outdoors.

“I think families traveling really have to gear their expectations and activities toward the children,” she said.

Even vaccinated travelers should be cautious

Rock said vaccinated travelers should consider if they have major health problems or are at high risk for severe illness.

Potential travelers should also look at infection rates and hospitalizations in the country or area they plan to visit, as well as vaccination rates. If those numbers are bad, she said, they should decide whether going to that specific place is essential or not.

“Is it essential travel to see a sick family member or something along that line?” she said. “Or is it travel for recreation or pleasure that could be done in an area where there is less covid-19 circulating?”

Want to cancel? Insurance might not cover the trip.

Most travel insurance provides coverage if a traveler gets the coronavirus before or during a trip, which includes cancellation if they can’t go because the virus, medical expenses if they become ill on the road or medical evacuation, according to Megan Moncrief, a spokesperson for travel insurance comparison site Squaremouth.

But if someone is just too nervous about the latest surge to go on a trip, a regular policy won’t help. Those who want that kind of flexibility need to buy more expensive “Cancel for Any Reason” coverage, which costs about 40 percent more than a standard policy and reimburses as much as 75 percent of the cost of a trip.

Moncrief said trip complications such as border closures and quarantine requirements would only be covered under that more expensive policy.

Future of the federal mask mandate is unclear

The Transportation Security Administration has extended its mask mandate in airports, on airplanes and on other forms of mass transportation until Sept. 13. It’s not clear how the delta variant might affect the agency’s decision about whether to extend the mandate.

TSA spokeswoman Lisa Farbstein said there was no decision to announce yet about the future of the requirement.

Rock said she would be “very surprised” if the mandate was dropped, “given the delta variant circulating and difficulty we have understanding who’s vaccinated and not.”