Public health officials, doctors, and scientists have been clear: With omicron spreading, COVID-19 cases rising and hospitals filling up, the safest way to celebrate Christmas this year is to stay home.

“It’s hard and it feels impossible and it feels unfair, but I know and our contact tracing tells us, that these gatherings when we get together with friends and family are when we infect each other with COVID-19,” Philadelphia Health Commissioner Cheryl Bettigole said earlier this month. “Please do not get together with other households for Christmas.”

The omicron variant, which now accounts for 73% of new U.S. cases, is highly contagious and skilled at evading immunity, either from vaccines or an earlier infection. What’s more, it appears to make people less sick, which means you could more easily spread it without knowing you’re carrying the virus.

But let’s be realistic. This close to the holiday, a lot of people aren’t going to change their plans.

AAA estimates 109 million people will travel this year for the holidays ― 27.7 million more than last year. The estimate is based on an annual survey of 50,000 families and while completed before omicron became widespread in the U.S., it represents a 34% increase in holiday travel compared to last year.

While imploring people to skip holiday gatherings, Bettigole added, “If you do keep those gatherings small, have everyone do a rapid test before they come and ask everyone to stay home if you feel even a little bit unwell.”

So to summarize: COVID-19 remains a major threat this holiday season. You should stay home. For those who won’t, here’s what you should know:

What’s the safest setting for gathering with friends and family?

A small, outdoor gathering of people who are vaccinated, boosted, and recently received a negative COVID-19 test is the safest scenario for a holiday gathering this year.

“We’re in a phase of the pandemic with such high levels of infection with a virus that spreads so rapidly, it is best for people to act as though they themselves are infectious and everyone around them is as well,” said Michael Levasseur, an epidemiologist at Drexel University.

The urge to stay safe after almost two years of pandemic, though, is competing with people’s need for connection and some sense of normalcy.

“It is a big question mark,” said Thersa Sweet, associate professor in Drexel University’s department of epidemiology and biostatistics. “If everybody is vaccinated and the people who you’re around aren’t immunosuppressed, we’ve got to start living our lives.”

Outdoors is ideal for social gatherings, but if that isn’t an option, keep the group small and opt for a private setting, like your home, over a public space where there will be other groups of people with unknown vaccination status.

“In general, the more people you’re around who are unmasked in particular, the more people you’re around who you don’t know the vaccination status of, the more people in a room you don’t really trust, the more risk you’re taking,” said William Surkis, vice president for medical education at Lankenau Medical Center, which is part of Main Line Health.

» READ MORE: Make this DIY air filter to (possibly) reduce your indoor exposure to coronavirus

Ventilation can help reduce risk when gathering indoors.

“But it isn’t going to afford 100% protection,” Sweet said, “and it’s kind of cold out.”

How soon before I attend a holiday gathering should I get tested?

If you are getting tested purely for peace of mind before seeing family (meaning you are not experiencing symptoms and were not exposed to anyone who tested positive), aim to get tested as close to party time as possible. At-home rapid tests can give you results in 15 minutes. Rapid tests can tell with high accuracy whether you have enough virus in your system to be contagious at that moment, which would be good to know before letting grandma pinch your cheeks.

» READ MORE: Looking for a free at-home COVID-19 test in the Philly region? Demand is outstripping supply.

When is the best time to get tested if I may have been exposed?

Research shows that most COVID-19 tests aren’t effective at detecting the virus until it has been in your system for at least two days.

The sweet spot for getting tested appears to be five to seven days after an exposure, said Shawn Naqvi, chief medical officer at Personic Health Care, a Delaware County-based company that launched during the pandemic to provide COVID-19 testing.

“If you did pick up an infection, it’s shed enough to get picked up on a test. If you’re asymptomatic, that’s a pretty reliable window if you get a negative,” he said.

What type of test should I get?

PCR, or Polymerase Chain Reaction, tests are the most reliable because they detect genetic material of the virus. That means they can detect the virus before people develop symptoms and when smaller viral loads are present. They require advanced laboratory equipment to process and results can take a few days to receive. PCR tests are a good option for people who are not experiencing any symptoms and who have a couple days before seeing family for results to come back.

Rapid antigen tests are less sensitive than PCR tests but still highly reliable in detecting whether you have enough virus in your system at that moment to infect others. Results are available within 15 minutes and up to a few hours, depending on whether you use an at-home kit or go to a test site. Rapid tests are a good option if you want to know if you are sick right now. But because the tests are less sensitive, a negative result today does not rule out the possibility of being contagious tomorrow.

Should I get tested before a gathering even if I feel fine?

Yes. Asymptomatic COVID-19 is common, especially with omicron on the rise. The omicron variant is sneakily good at evading vaccines and natural immunity, and seems to lead to less severe symptoms. But it’s possible you could give the virus to someone who is older or has underlying conditions that could mean a serious illness.

“The safest thing is to just get a test,” Naqvi said. “On a daily basis I talk to people who say, ‘Oh my God, I can’t believe it was positive.”

Do I need an appointment for an in-person COVID-19 test?

Appointments are encouraged for most testing sites and pharmacies, though open time-slots can be hard to find. Appointments help providers gauge how many tests they’ll need that day and adjust staffing levels to accommodate demand. But most testing locations also accept walk-ins. You may have to wait longer or make a couple stops to find a place without a line, but with patience and persistence, you should be able to get tested. Before heading out, check online to find locations and operating hours.

What else can I do to protect myself and others?

Getting a COVID-19 test to confirm you’re not sick is great, but more important, get vaccinated and get a booster when you’re able, Main Line’s Surkis said. Mask wearing and social distancing may be getting old, but can make a big difference in reducing the risk of contracting COVID-19.

If you’re hosting, be selective about your guest list, inviting only people you know are vaccinated and have been taking safety precautions.

“This may be the moment to think very carefully about who’s coming and their level of care,” he said. “I do not feel comfortable socializing with unvaccinated people or bringing them into my household.”

As a guest, you have less control. If you feel comfortable, talk to the host in advance about how many people are coming, if their vaccine status is known and what safety measures will be in place at the gathering.