The end of the year is sneaking up, and people are weighing travel plans to join friends and family for the holidays against the backdrop of a surge of the Covid-19 pandemic.
Gathering with others -- probably the most universal holiday tradition -- has never required so much meticulous forethought.
Should you travel for the holidays in 2020? What precautions will make it safer? Who will be there and how careful have they been?
CNN spoke with medical experts about holiday travel risks and when you really should skip it altogether.
Should you travel for the holidays this year?
Health and government officials are increasingly urging people to stay home and avoid nonessential travel.
Gov. Jared Polis of Colorado urged residents to avoid Thanksgiving gatherings, comparing the holiday tradition to playing "Russian roulette" with family members who are most at risk.
He called on those who plan to attend intergenerational Thanksgiving gatherings to begin self-quarantining on November 13.
Canada's Thanksgiving celebrations, which take place in October, have spurred a dramatic surge in Covid-19 cases.
"What we do in the coming days and weeks will determine what we get to do at Christmas," said Prime Minister Justin Trudeau in mid-November.
The US Centers for Disease Control and Prevention says that travel increases the chances of contracting and spreading Covid-19. "Staying home is the best way to protect yourself and others," the CDC says.
The agency has created travel risk guidelines that break down components of travel from transportation to lodging and personal contact, rating choices from "lowest risk" to "highest risk."
Pay close attention to the case counts in your destination, the CDC advises. The risk of infection increases in areas with high community transmission.
"If you do choose to travel, try to keep gatherings small and take precautions," such as wearing a mask and practicing social distancing and good hand hygiene, said Dr. Henry Wu, director of Emory TravelWell Center and associate professor of infectious diseases at Emory University School of Medicine in Atlanta.
Who should skip it?
People who are especially vulnerable to severe Covid-19 illness are safest staying home.
"Are you older, are you frail, do you have chronic underlying illnesses?" are the questions to ask, says Dr. William Schaffner, an infectious diseases specialist at Vanderbilt University Medical Center in Nashville, Tennessee.
People who are considering meeting up with vulnerable relatives or friends should really weigh the implications of introducing illness to them, Wu said.
"There are well-documented Covid-19 clusters associated with family gatherings, including ones that resulted in deaths," he said.
Are some locations safer than others?
Gatherings are likely safer in areas around the world where infections remain low, although the standard precautions still apply.
For example, in early October Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said it might be possible to have a "relatively normal" Thanksgiving gathering in parts of the United States where infections are very low.
"But in other areas of the country ... you'd better hold off and maybe just have immediate family," Fauci told CNN's Chris Cuomo. As always, wear masks and keep gatherings small to reduce the risk of infection.
Cases have since spiked dramatically across the nation making gathering in most places riskier than it was just a month ago.
Getting together with people outside of your immediate household and mixing guests from different geographic areas raises your risk of infection.
Does testing provide protection?
Testing can help catch coronavirus infections before travel, Wu said,"but testing is not foolproof."
"It can be falsely negative, or just miss infections you are still incubating," he said. "You could certainly also get infected during travel and potentially infect others after that."
Testing can offer "a level of reassurance if the people who are attending are negative at the time they were tested," Schaffner said. "You still have to be cautious."
Would a vaccine make travel safe?
Even if a vaccine were widely available in time for the holidays, it would likely provide partial protection much like the flu vaccine, says Schaffner.
If it's 70% effective, then three people out of every 10 won't be protected, plus a sizable percentage of the population won't have been vaccinated yet.
It's not a "suit of armor," he says, and the other standard precautions would still apply.
Pfizer said in early November that the vaccine it is testing was more than 90% effective in preventing infection in volunteers. Government officials are working on complex distribution plans for the vaccine.
What's the safest way to get there?
Driving generally allows travelers more control of their interactions with other people than flying or other forms of communal transportation, the experts say.
The CDC rates "short trips by car with members of your household with no stops along the way" in its "lowest risk" category, next to staying home.
Minimizing contact when you get out of the car is key, Schaffner says. Mask up when you're outside the vehicle, make your stops few and brief and opt for drive-thru food over going inside a restaurant.
With air travel, "you're more at the mercy of what's happening around you," Schaffner said. Still, wearing masks, good hand hygiene and maintaining as much social distance as possible is important.
Flights with layovers are rated "highest risk" by the CDC.
Should you stay with family?
Staying in a rental house or cabin with your immediate household is a lower risk than staying in hotels or someone else's home, according to the CDC's risk assessment.
Schaffner sees hotels as offering more control of your environment than staying in a relative's home, provided you avoid close encounters in elevators and other public areas and skip restaurant dining in favor of takeout or room service.
Whether you choose to stay in someone's home "has a lot to do with who's the relative and how careful have they been," Schaffner said.
Anytime you're gathering in close contact with friends or relatives, it's important to discuss these things in detail beforehand: Is anyone at elevated risk for severe disease? What kinds of precautions and risks are guests and hosts taking day to day?
Schaffner knows people who have stayed in the homes of friends or relatives after carefully quarantining for a couple of weeks before visiting or receiving guests. That's the kind of safety measure that's good to consider and agree upon in advance.
Wu doesn't have a strict answer on whether staying with friends and family or in a hotel is safer. A number of factors come into play, he says, including your ability to safely distance. For stays in the same house with other people, "consider if the family you are visiting has been able to isolate and take precautions," he says.
Can you safely gather with people outside your household?
Even if you do stay in a hotel or rental home, chances are good that you'll want to gather with other households to celebrate the holiday season.
Schaffner has been to relatives' homes during the pandemic and they've been to his, but they've stayed far apart and worn masks and only stayed together for a couple of hours, he says.
Food is served, but they sit at the far ends of the dining room table and take their masks off only to eat and drink.
"It is prudent to keep the mask on during a family gathering, especially if indoors and you (or others) have risk factors for severe illness," Wu said.
Small, outdoor, socially distanced gatherings are safest. If you gather inside, choose an open, well-ventilated space.
"Large groups, especially if coming from different households or geographic locations, could increase the risk of infection," Wu said.
The very safest option? "Get a small turkey and stay at home," Schaffner says.
CNN's Jenn Selva, Paula Newton and Jen Christensen contributed to this report.