(CNN) — In any other year, we'd be happily flying over the rivers and past the woods to get to Grandma's house more quickly for the holidays. But it's 2020, and globally there are more than 1.6 million deaths from the novel coronavirus so far -- with no end in sight. "I'm particularly worried about air travel," said pediatrician Dr. David Rubin, who directs PolicyLab, a research and public policy center at Children's Hospital of Philadelphia. The center is tracking Covid-19 cases in communities across the country.
"I almost think that cars are safer for those who are traveling, because it's just you and whoever you're traveling with," Rubin said. "At least you don't have the situation of a packed airplane where there might be several Covid-19 positive individuals on the plane."
Masking and maintaining as much distance as possible are key to reducing the risk of coronavirus transmission.
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Just about everywhere you might travel, the numbers are grim. Europe is deep into a second wave of the pandemic, and cases of Covid-19 are skyrocketing in many areas of the United States.
No way to keep virus off flights
That means safety checks put into place by the Transportation Security Administration (TSA) -- as good as they may be -- aren't likely to catch anyone who is shedding the virus without obvious symptoms such as cough or fever.
"If you're on a big plane now there's a reasonable chance that someone who's infected with Covid-19 is going to be on that plane," said Linsey Marr, a professor of civil and environmental engineering at Virginia Tech who is a leading expert in aerosol transmission of viruses.
Rubin said that with the pressure to get home for the holidays, he suspects "there are going to be people who test positive (for coronavirus) who are going to jump on the airplane anyway."
Plane ventilation systems
When it comes to infectious disease, airplanes have an excellent safety record because the air people breathe while flying is some of the most filtered air in travel, according to Joseph Allen, who directs the Healthy Buildings program at the Harvard T.H. Chan School of Public Health.
"The air in (many) planes is a 50/50 mix of outdoor air and recirculated air," Allen said. "The outdoor air is bled off the engine, conditioned and delivered into the cabin. The other 50% is recirculated air that goes through HEPA filters."
All major commercial jets have ventilation systems with high-quality HEPA filters capable of removing 99.97% of dust, pollen, mold, bacteria and other airborne particles with a size as small as 0.3 microns. For comparison, Covid-19 is thought to be between 0.06 to 1.4 microns.
When those ventilation systems are running and everyone is masked, the risk of Covid-19 is greatly reduced, according to Marr.
"I would say going to a restaurant is riskier than sitting on an airplane on one of the bigger jets," Marr said. "It's the other parts of the trip that concern me more."
The rest of the air travel experience
Take the boarding process. Jet causeways can be packed, as people stack up waiting their turn -- only to enter a parked plane that likely has little to no air recirculation.
"During boarding that's when there's usually no ventilation -- the planes don't have their auxiliary power units going, they're not often tied into the gate-based ventilation systems," Allen said.
If many seats are sold and the boarding process is slow, that may up your odds until the air flow and filtration starts.
"We've done measurements on airplanes when people are boarding, and we see high levels of carbon dioxide, which is an indicator that there's insufficient ventilation," Allen said.
Trains and airport shuttles also put you in closer-than-6-feet contact with others; and if you traveled to the airport in an Uber or taxi, you were in another small space.
"Think about the entire travel-related experience," Allen said. "You may be taking a taxi or a bus or subway, dealing with security queues, or visiting the restaurant at the airport."
Here's the key question to answer: No matter how safe plane travel is -- and no matter how well ventilated an airplane cabin on a major airline may be -- should you fly for the holidays?
No, says Allen. "Right now, we shouldn't be traveling unless it's absolutely necessary," he said. "It's difficult, we all are suffering from pandemic fatigue, we're ready for this to be over, but the reality is it's not over.
"We have a shared responsibility to act appropriately and minimize how quickly this virus continues to spread."
Tips to lessen your risk
What if, despite your best efforts to avoid air travel, it does become a necessity to fly? Here are experts tips on how to reduce your risk of catching Covid-19 along your journey.
Fly short distances.
The amount of time you're exposed to the virus matters, according to CNN commentator Erin Bromage, a comparative immunologist and professor of biology at the University of Massachusetts Dartmouth.
In May, he wrote a blog post viewed millions of times that defined the likelihood of catching the virus with this equation: "Successful Infection = Exposure to Virus x Time." Apply that to air travel and it follows that shorter flights will expose you to less virus, thus reducing your risk.
"The rare cases where we have seen transmission on airplanes it's on the long flights, the ones that are five hours, or more like nine hours, 14 hours," Marr said.
- Tip: Need to fly longer than a few hours? Break up the trip, Marr suggests. Fly several shorter hops, with time to get off the plane and into fresh air. Or drive part of the way and fly the rest.
Plan your transportation to the airport.
If you have to take an Uber, Lyft or taxi to the airport, make sure you, your family and the driver are all masked throughout the journey -- and be sure to roll down the windows to encourage air flow, Allen said.
"We've done some modeling on this, we're showing that even rolling down the windows just a couple inches can really help with airborne transmission," he said. "And you want to put down the windows even if it's inclement weather. A little bit will really help."
- Tip: You can also drive yourself and the people in your "pod" to the airport and leave the car parked. Even then, Allen said, roll down the windows.
Wear a proper mask, the proper way, for the entire journey.
Wear a mask that covers your mouth and nose throughout your flight and stay seated as much as possible.
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"You want to have a minimum two-ply mask, preferably a three-ply mask," said Allen, who has focused his career on "sick buildings" and how they affect worker performance and productivity. Look for a tight weave of 100% cotton, according to studies. Use the light test to check the weave: If you can easily see the outline of the individual fibers when you hold up the mask to the light, it's not likely to be effective.
"In addition to level of filtration, we have to pay attention to fit," Allen continued. "You want the mask to go over the bridge of the nose, below the chin and be flush on the face, resting along the skin. You want your breath going through the filter media and not escaping out the sides."
Even the most protective mask will fail if you wear it wrong. Full face coverage is necessary at all times, and that means no letting it slip under your nose, please.
Consider a face shield.
If you're high risk, you might consider adding a face shield over the face mask, said Dr. Henry Wu, an associate professor of infectious diseases at Emory University School of Medicine in Atlanta.
"We don't quite have the data yet to say how much additional protection it offers," Wu said, "but it may have some additive value, particularly in terms of larger respiratory droplets directly getting into your eyes."
But don't rely on a shield alone, Wu cautioned: "Wearing a face shield does not negate the need to wear a face mask."
Air travel has picked up significantly since its near standstill in March. The TSA screened more than a million passengers on October 19.
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Carry the essentials.
Along with that highly protective mask, you should definitely bring disinfecting wipes and a 3-ounce bottle of hand sanitizer with greater than 60% ethanol or 70% isopropyl alcohol. That's the level needed to kill most coronaviruses, according to the CDC.
Don't be fooled by the "99.9%" effective marketing language you may see on the bottle. Instead, check the ingredients for alcohol levels or look for the US Food and Drug Administration's "Drug Facts" label. You can also check out the FDA list of approved disinfectants.
Before you sit, use sanitizing wipes on your seat and arm rest on the plane, and don't forget your seat belt, the filtration nozzle and light buttons above your head, the video monitor and the back of the seat in front of you.
Bring your own ear buds, neck pillow and blanket if you think you need them, and don't forget snacks you can bring from home, such as dried fruit, nuts, cheese and crackers. Most airlines have reduced meal service to a minimum.
Maintaining 6 feet of social distance in airports can be challenging.
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Build in extra time.
Don't expect to breeze through the airport as in days of old. It takes more time to social distance during baggage drop off and security checks. Minimize the time you spend in security -- no loose change, no belts, no shoes with ties, take off and store your jacket in advance -- and have your laptop and carry-on toiletries at the ready.
Stay in your seat if you can.
Getting up and moving around puts you closer to others on the plane, and visiting the bathroom opens up a whole new set of potentially germy things to touch. Try to prepare for that in advance, Wu said, by "having your meals before the flight and doing your bathroom breaks on the layovers."
If you must take a bathroom break on the plane, that's all the more reason for having hand sanitizer at the ready, Wu said.
"That's a much better approach than wearing gloves," he said. "The reality is the gloves just protect the surfaces of your hands. The outside of the glove is obviously still dirty, and if you have dirty gloves and are touching your face, it's really no different than not having gloves."
Quarantine upon arrival -- both ways.
"Don't rely on a negative test on the Tuesday before Thanksgiving and think that clears you to be with your family," Rubin said. "Quarantining for a week and a half when you arrive is your best way to assure that you're likely to be negative."
Taking that precaution works both ways, Allen said.
"I do think it's responsible that when you arrive somewhere or you return that you quarantine and make sure you're not bringing infection into a new area or returning one to wherever you live," he said.
"This is not the time for luxury travel or vacation travel," Allen added, "but if you absolutely must travel -- and there are many reasons why people have to travel -- you just have to take extra precautions."