For a blissful few weeks this spring, a summer of semi-normal travel seemed not just possible, but almost certain. Flights were booked, hotel reservations were made and vacation time was requested as those with wanderlust or pent-up desire to see loved ones organized their long-awaited excursions.

But the hyper-transmissible delta variant of the coronavirus has now forced some would-be travelers to cancel trips and others to consider whether it’s safe to follow through with their plans. As hospitalizations surge across much of the country — mostly among the unvaccinated — Americans are trying to adapt on the fly.

Asking yourself a few questions can help you decide whether to keep your travel arrangements.

Is everyone in your group of travelers vaccinated? Is anyone immunocompromised?

If you haven’t gotten vaccinated against the coronavirus, you should strongly consider staying home, experts said. Travel is much safer if at least two weeks have passed since your last dose. But if you have a weakened immune system, you may want to reconsider traveling, even if you have been vaccinated.

“If they have issues with their immune system or are immunocompromised, I would say now is probably not a great time to travel, because there are so many things that are outside of your control,” said Nasia Safdar, medical director of infection control at the University of Wisconsin Hospital and Clinics.

The status of anyone you’re going to visit also matters. Safdar said she would wear a mask around immunocompromised family members or friends, even in private settings where everyone has been vaccinated.

For unvaccinated people who must travel, the Centers for Disease Control and Prevention suggests taking a coronavirus test one to three days beforehand, staying away from crowds and remaining masked. You should also take another virus test three to five days after returning and self-quarantine for seven days. Also, keep in mind that some countries or venues might require children who are too young for vaccination to test negative for the virus.

How do you plan to travel?

To avoid contracting or transmitting the virus, the fewer fellow travelers you come into contact with, the better. For that reason, traveling by car is generally safer than taking a train, bus or airplane. Try to make as few stops as possible, because rest stops and gas stations will probably put you in proximity to many other travelers.

If you travel by air, you have a particularly high likelihood of ending up in a crowd. Although the virus doesn’t seem to spread easily on flights, you’ll probably be among hundreds or thousands of other passengers at an airport terminal or while in line for a security check.

Remember that masks are required on all public transportation and at transportation hubs such as airports. You should make sure the mask you bring meets your airline’s requirements, said Alvin Tran, an assistant professor of public health at the University of New Haven’s School of Health Sciences. Bandannas, scarves, balaclavas and face shields are often considered insufficient.

Before boarding an international flight, you may have to take a coronavirus test at your own expense and show proof of a negative result, said Lin Chen, director of the Travel Medicine Center at Mount Auburn Hospital in Cambridge, Mass.

What’s the transmission rate at your destination?

The CDC maintains a map showing which regions of the United States have low, moderate, substantial and high rates of virus transmission at a given time. A separate guide tracks coronavirus prevalence in various countries and offers recommendations associated with each level of transmission. Travelers should avoid visiting areas with a “very high” degree of transmission, per the CDC’s guidelines.

Although it can be helpful to consult that data, Safdar suggested keeping in mind that regions can move quickly from one transmission category to another. So what looks like a low-risk destination when you’re planning may not be quite as safe by the time you arrive. For example, on Aug. 2, the CDC and the State Department added 16 destinations — including Ireland, Greece and the U.S. Virgin Islands — to their highest travel advisory category for the coronavirus.

A region’s immunization rate and the status of its hospitals also matter. There is probably more virus circulating in low-vaccination areas, and overwhelmed hospitals may mean you’ll have less access to medical care if you get sick or injured — with covid-19 or any other malady.

Chen said to also consider how you would manage if you tested positive for the coronavirus while at your destination. You should be prepared to self-quarantine there until you’ve recovered.

What travel restrictions are in place where you’re going?

Although some destinations are loosening restrictions to encourage visitors, others are tightening them in response to the delta variant. On Aug. 3, Israel said it would require visitors from the United States and 17 other countries to quarantine upon arrival, regardless of their vaccination status. Grenada now requires full vaccination for entry. Australia’s most populous city, Sydney, has been locked down for weeks.

On Aug. 9, the CDC added countries to its list of Level 4 — or very high — travel risk. France, Iceland, Israel and Thailand are included in the countries that the agency urges people to avoid.

Some countries, including France and Italy, are beginning to require proof of inoculation, documentation of immunity or a recent negative coronavirus test for entry to certain establishments. Chen cautioned that some foreign venues may not accept a CDC vaccination card as proof of immunization.

In the United States, many restaurants and bars also have said they’ll require vaccination. If you haven’t gotten your shots, consider whether the rules of the businesses you want to visit would prohibit you from going.

Will you spend most of your trip indoors or outdoors?

It has been clear for months that the coronavirus spreads more easily inside than outside, so where you’ll be spending most of your trip should be a consideration in whether to go through with it. Hiking in a national park, for example, is low on the spectrum of risk. But Tran cautioned that he would still wear a mask while in line for an outdoor attraction, where social distancing is difficult.

If you’ll mostly be visiting museums, historic buildings and shops, on the other hand, you should consider the fact that the CDC is urging indoor mask-wearing in areas with substantial or high coronavirus transmission. And some jurisdictions, such as Nevada, D.C., Los Angeles County, St. Louis and others, are issuing mask mandates for indoor public spaces on their own. So, depending on your destination, you may need to wear a face covering for hours at a time. Jurisdictions may also have rules regarding social distancing and the hours that different types of venues can be open.

If you’re partaking in indoor activities, Safdar suggested keeping a low threshold for donning a face covering. And she said she would avoid indoor dining at any destination.

Can you get your money back if your travel plans change?

Your calculus for determining whether to go on a planned trip may depend in part on whether you can reschedule or cancel without losing money. Most travel insurance will reimburse you if you get the coronavirus before or during a trip but won’t help if you want to cancel out of nervousness about the delta surge, Megan Moncrief, a spokeswoman for travel insurance comparison site Squaremouth, previously told The Washington Post. She said you’d have to buy pricier “Cancel for Any Reason” coverage to account for that scenario.

How much risk and inconvenience are you willing to endure?

In this pandemic, there’s no such thing as a trip with zero chance of contracting the coronavirus. Whether it’s worth it to travel depends largely on your comfort level with risk. In a high-transmission area, Safdar said, it will be very hard to avoid the virus entirely.

Traveling right now also requires more preparation than usual. You’ll have to stay on top of evolving requirements and restrictions, even while at your destination, and adapt accordingly. You also may need to budget extra time and money to compensate. If you can afford to do so, working with a reputable travel agency can help you work through those challenges, Chen said.

“If somebody is prepared to face all those additional challenges, they might be okay and want to go anyway,” she said. “But I think for a lot of people, it might not be worth all the extra efforts.”

PLEASE NOTE: Potential travelers should take local and national public health directives regarding the pandemic into consideration before planning any trips. Travel health notice information can be found on the Centers for Disease Control and Prevention’s interactive map showing travel recommendations by destination and the CDC’s travel health notice webpage.