(CNN) As Omicron spreads rapidly throughout the United States, the new coronavirus variant has taken over from Delta as the dominant strain.
Dr. Anthony Fauci, the nation's top infectious disease expert, warned on CNN's "State of the Union" on Sunday that Americans should brace for a difficult few weeks ahead.
The Omicron variant is now the dominant strain of coronavirus in the US, accounting for over 73% of new coronavirus cases last week, according to data posted Monday by the US Centers for Disease Control and Prevention.
With Christmas, New Year's, Kwanzaa and other winter holidays just around the corner, many people are wondering what they should do. Is it time to cancel holiday gatherings? How safe is it to travel? What additional precautions should be taken if you decide to go?
For guidance, I spoke with CNN Medical Analyst Dr. Leana Wen, who is an emergency physician and professor of health policy and management at the George Washington University Milken Institute School of Public Health. She is also author of a new book, "Lifelines: A Doctor's Journey in the Fight for Public Health."
CNN: Two weeks ago, you said that people shouldn't change their holiday plans because of Omicron. Is that still the case?
Dr. Leana Wen: A lot has changed in two weeks. At that point, it wasn't clear how much the Omicron variant would be spreading here in the United States. Now, we are seeing skyrocketing Omicron cases in some parts of the country. It's become very clear just how contagious Omicron is.
All that said, I don't think people should be canceling all their holiday plans. I do think it's prudent to re-evaluate them and make a risk-benefit calculation based on each family's circumstance.
CNN: What factors go into this risk-benefit decision?
Wen: First, what is the medical risk of your household? Based on what we are seeing thus far, Omicron seems to cause mostly mild symptoms in vaccinated individuals. If everyone in your household is vaccinated and boosted, and generally healthy, I believe that the risk of severe disease caused by Omicron will be low.
Second, what's the value of the specific holiday plan to you? A lot of people would say that getting together with their loved ones is really important. An office holiday party might be less important. Remember that risk is cumulative. You could decide to go to one event and not another.
Third, how risky is the actual get-together? A small dinner party where everyone is vaccinated and boosted, and where same-day testing is required, is relatively low risk. The risk becomes even lower if you know that everyone at the event is cautious in their daily lives and always masks when out in public and never goes to crowded restaurants or bars. The risk is higher if there's no testing, if vaccination status is unknown, or if some individuals have higher exposures.
CNN: There are reports of events where everyone is vaccinated, but people still get infected with Covid-19. Should people feel safe going to indoor gatherings, even with proof of vaccination?
Wen: Very few activities are totally without Covid-19 risk. The risk of contracting the virus is certainly lower if you are surrounded by people who are also vaccinated, because they are less likely to be infected themselves and therefore less likely to spread it to you.
I've equated the vaccine to a very good raincoat. It protects you very well if there's a drizzle. But if there's a constant thunderstorm, you could still get wet. When there is a lot of virus around us, as is the case for most communities across the United States, we need additional protection.
What I propose is a "two out of three" rule. Indoors, when there's a lot of virus, you need two out of three layers of protection: vaccination, Covid-19 testing and masking. (Outdoors remains very safe.)
If you want to go an indoor gathering where people are eating and drinking -- and therefore unmasked -- and it's an area with high viral spread, you need proof of vaccination and same-day testing. If testing isn't available, keeping your mask on gives that added layer of protection. If vaccination is not required, or if there are unvaccinated individuals in attendance, then masking in addition to testing will be protective.
CNN: How safe is it to travel? Should people cancel their travel plans?
Wen: The travel itself is not my major concern. Airplanes and airports require masks, for example, and you can keep yourself safe by wearing a high-quality N95 or KN95 mask the entire time. My main worry is what people do after they travel. If they are only going to spend time with a small group of family members who are all vaccinated and tested, that's still relatively lower risk. On the other hand, if the plan is to go to a lot of indoor restaurants and attend holiday parties with unvaccinated people, that's much higher risk.
If you travel, make sure you have a plan for what happens if you test positive. Also, if you are planning to come back and visit vulnerable individuals — such as an aunt or uncle in a nursing home — make sure to quarantine for at least three days and then get tested before seeing someone medically frail. And if you fly internationally, follow travel requirements carefully so that you don't end up getting stuck because of new quarantine or testing rules.
CNN: What about people with little kids who are still too young to be vaccinated?
Wen: I'm in this situation, with two kids under the age of 5 who are still not eligible for vaccination. My daughter is under 2 and cannot mask reliably, so we are not traveling by plane or going to settings where she could be surrounded by unmasked and unvaccinated people.
We don't yet know the effect of Omicron on young kids, but what we do know is that this is an extremely contagious variant—more contagious than we've seen with previous strains. Young, unvaccinated kids and all unvaccinated people are more at risk than ever before from getting infected. That's a reason to use additional precautions for those with unvaccinated family members.
CNN: How will you be celebrating the holidays?
Wen: My husband and I will be going to several holiday gatherings, some with and some without our children.
The major event is a Christmas party with a couple dozen people, where vaccination and boosters are required, along with testing. Vaccine cards and test results will be checked at the door, and all individuals are low-risk in other aspects of their lives. The kids are not going to that event, since the only individuals permitted are those who are vaccinated.
We will also be going to two more holiday gatherings with our kids. One is outdoors only, weather-permitting. The other is with another fully vaccinated and boosted family who will all test for Covid the day of the event, as will we.
All these precautions help to reduce risk. They don't remove risk altogether, but the level of risk is something we are OK with because of the value of these events to us. At this point in the pandemic, we must find strategies that help us to live with Covid-19, even with the threat of Omicron.