Flying in the age of COVID-19

written May 16th

The evidence of how indoor spaces facilitate transmission keeps mounting. There are recent publications describing a COVID-19 outbreak cluster associated with a bus excursion where 23 out of 67 passengers became infected, a person's outing to a nightclub that led to at least 80 new cases, and a training workshop where 15 of 30 attendees all became ill. In addition to these studies, an important study published on Wednesday revealed findings that 1 minute of loud speaking could create at least 1,000 respiratory droplets that remain suspended in the air for up to 8 minutes. They estimated, but did not experimentally demonstrate, that these droplets may contain between 1,000-100,000 infectious viral particles.

Now that we have strong evidence demonstrating the ease with which this virus can be transmitted in enclosed spaces, we must start to evaluate our decisions to bring large numbers of people together, especially in stressful situations. For example, the thought of bringing 1000 students together, over 2 days, to sit the Florida bar exam, certainly has my attention.

These new examples and the science that is supporting transmission via respiratory emissions must make us pause and carefully consider our individual decisions about where we go and how long we spend in public locations, to the extent that our lives and employment situations allow us to choose where we spend our days.

Data Update:

Australia: Keep doing you! The cohesive response of Federal and State leaders, the buy-in from the Australian public, and the early testing and tracing program is why very soon you will be enjoying a beer at the pub. There is some trouble in Victoria associated with a restaurant and a meat processing facility, but if that can be contained through the test, trace, and isolate program, then the national numbers will be very low. Keep being vigilant.

MA and RI: The trends in infection rates in MA and RI are looking really promising. I am relieved that, through the measures imposed by our states' leaders, the curve has bent hard. For MA, the two most encouraging signs are the increased testing but lower test-to-case ratio (testing more and finding fewer cases) and the number of people in hospitals are decreasing at a faster rate than previously observed. Daily case numbers are still high (~1000 per day) and I would love to see them come even lower before we really get going as a state again. But we have done well. I still have concerns about the number of people in ICU beds in MA. At the peak of this outbreak, we approached our non-surge ICU capacity. Since that peak, the number of people in intensive care is only slowly dropping. It just shows how long and how tough it is for some people to recover from this bug.

USA: In general, the trends in the USA are looking better: 41 states are declining or are stable, while 9 are still rising (as of May 15). These trends, while important, also need to be considered alongside how many new cases per day are being identified. If your state has declining cases, but is still identifying hundreds or thousands of new cases per day, that is more troubling than being in a stable state that has only 50 new cases per day.

We are heading the right way, and I hope that we don't go back the other way.

Flying

As restriction on our movements in Australia, NZ, and the US are being lifted, many of us are trying to assess the risk of flying. In Australia and New Zealand, all but the most essential flights are still grounded, while in the USA the number of flights has been reduced, but the number of people on those flights has been extraordinarily low.

As Australia and NZ have absolutely crushed the curve, there are plans to reopen domestic flights and discussions are being had to resume services between the two nations. Many of us in the USA are also considering flying for work, to visit family, or in a number of circumstances such as reuniting families after cities were placed in lock down.

It's a new world with new risks.

There are many reasons why you might need to travel in the upcoming months. For some (many?) the risk of infection during travel will be outweighed by the need to get to another place, whether for family or work or other personal reasons. Back in early March, my wife and I had to decide whether to proceed with a long-scheduled trip to Australia to visit family. We ultimately decided to go - the risk to us was outweighed by our desire to see my parents and sister.

When we left, things were heating up in the US. I had been keeping a close watch on the outbreaks in Australia and the USA, and I knew there were several risks if we traveled, but I really wanted to see my family. I also knew that if we canceled our trip, it was going to be a while before I could see them again.

Adding to my concern was that my parents are not young (sorry Mum and Dad), and the evidence coming out of China in late February/early March suggested that they were in the target demographic for this virus. So, I started reading like crazy and began making plans on how to reduce our exposure risks during our travels, and therefore, to reduce the risk of hurting those I care about.

I had been training my wife and kids for weeks on the "rules": limiting touching surfaces, washing our hands often, and not touching our faces. It's hard to break years of habits though. We also had some fun games practicing how to open doors or press elevator buttons with elbows and knees. After all, we needed to be cautious, but not always serious.

Key things we took with us:

• Small hand sanitizers that would get through TSA screening. We had the type that could attach onto our jeans/shorts so we didn't have to put our hands into a bag or pocket to get it.

• Disinfecting wipes. We took a whole plastic tube of disinfecting wipes and put them in a clear ziploc bag. TSA flagged it, examined it, and questioned it, but let it through. Note for next time: just take a reasonable amount.

• A full set of clothes in our carry-on bags to change into when we got to Australia (more on why later).

• We wore sweatshirts with pockets. Sounds strange, but trying to tell kids not to touch anything does not work so well. But, telling them to keep their hands buried in their hoody pockets worked (for me too!).

To and from airport: Parking at the airport costs a fortune, so we had arranged for a friend to drive us to the airport and then take our car home. The plan would be reversed on the return leg. For the critics, this was prior to any social distancing restrictions. We did have to adjust the return pickup plan, because by then everything had changed.

In the Airport: It was just vigilance as usual. Don't touch surfaces. If we did touch something then we sanitized our hands. Don't touch our faces. We did not have face masks as, at the time, there was so much conflicting information about their usefulness (see a new post coming soon - they are useful!), and the ones I had ordered a month prior still hadn't arrived.

Playing it overly cautious, we just kept appropriate physical distance from people, and avoided getting crowded in choke points. We couldn't check in online, as it was an international flight, but we made sure that only one of us was the "contact person" with the staff at check in and security to limit our family's interaction with others.

This is important: It is our interactions with people that lead to transmission chains. The more interactions, the greater the chance of either infection or transmission. While in the airport, just have a single person for all person-to-person interactions with airport staff or shops.

I am assuming that things have improved in regards to physical distancing during security screening and the boarding process. For us, in the early days of COVID-19, we just guarded our space.

On the plane: Stop touching surfaces! As soon as we boarded the plane, out came the disinfecting wipes. We wiped down every single surface we would touch. Armrest. Table. Monitor etc.

I understand airlines are now using some pretty innovative disinfection of surfaces and seats between flights but, in early March, for a few minutes of hassle, it was worth the peace of mind.

On the flights (22 hrs in planes), we just did our best to minimize touching surfaces when we had to move to stretch legs/bathroom and we always had hand sanitizer available.

BUT IT'S AN ENCLOSED SPACE!

A plane is a seriously enclosed space, with little air volume, and you are there for an extended period. It appears to have all of the parameters needed for outbreak calamity. But there is a big difference with planes compared to other enclosed spaces because planes have substantial air-filtration and air-exchange.

On modern Boeing planes (others may be the same), the entire air volume of the cabin is exchanged with outside air every 4 to 5 minutes (12 to 15 cabin air exchanges per hour). Additionally, the cabin air is filtered through a HEPA filtration system 25-30 times per hour (Ref)

As a point of reference:

HEPA Filters: are required to capture 99.97% of all particles >0.3 micrometers.

N95 respirators: are required to capture 95% of all particles >0.3 micrometers

So the HEPA filters in a plane have a higher filtering capacity than the N95 masks doctors and nurses are wearing when they are caring for COVID-19 patients. Granted, the respirators filter 100% of inhaled air, but the point is, aircraft have a substantial air filtration capacity.

I also discovered that the design of the air filtration systems on planes divides the planes up into zones of about 5-7 rows per zone. The bigger the plane, the more zones. Basically, the plane is divided up into air compartments so the emissions from someone 10 rows behind you is going to have little effect on you due to the zoning, filtration, and air exchange.

One last thing I learned: the little air nozzle above your head shoots our air directly from the HEPA filter. Directing that airstream on you increases the amount of HEPA-purified air you are inhaling. Turn it on!

Knowing these things about the cabin air, even without wearing a mask, gave me more confidence that the risk was low. All I had to worry about was surfaces and people within my sneeze-zone.

Note: Aircraft air starts to deteriorate when you are on the ground. Wait to get on the plane, and don't linger getting off the plane.

Arriving at Destination

The plan we had in place was to treat ourselves and our luggage as 'hot', meaning potentially contaminated. We just assumed our carry-on and luggage bags, as well as the clothes we were wearing, were all contaminated. Therefore, before meeting my parents, we wiped down all our luggage with the disinfectant wipes, put our plane-worn clothes in a garbage bag to launder later, showered, and got into our new clothes.

This was overkill, but again, I was aware of the risks infection would bring to my parents and I was going to be as careful as possible.

Needless to say, the trip was amazing.

However, days after we arrived, the infection rate in the USA was starting to soar, and we started to worry about whether we would get home. Australia was about to close their borders to foreigners and airlines were canceling flights.

Thankfully, we did make it home, as scheduled, and practiced all the same on-board precautions. The arrival in LAX was terrifying though. We were corralled like cattle and there was not a single question asked about sickness or travel to countries that had sustained outbreaks. Ughh.

Again, we just used a single person as the up-close contact person for the necessary interactions with customs agents and baggage collection to the extent we could.

The ride home: Two wonderful friends drove our car and another to the airport, dropped our car at the pickup zone, wiped down contact surfaces, waved from a distance, and disappeared.

Once home, we quarantined ourself in our house for two weeks, just to ensure that we didn’t become part of the problem.

So that is how the Bromage family navigated a long-haul flight from Boston - Sydney - Boston. Was it overkill? Maybe. But I wanted to travel as safely as possible. And everyone stayed healthy - us and my family in Australia. Dumb luck? Maybe. But also perhaps because we were careful and followed our self-imposed rules pretty closely.

What has changed since we traveled?

I have read that all major airlines are now requiring facemasks be worn on flights. Face masks aren't the be all and end all to reduce viral infection, but they definitely do help. If you are on a flight, have access to a N95, and you know how to wear it properly, then wear it. If you don't have a N95, then most other face coverings will have some level of positive effect at dropping the respiratory emissions from you to others. Collective use of masks is crucial to safe air-travel in the USA while case numbers are high.

Some airlines are restricting the numbers of passengers on the plane to give more physical spacing. Others will give you the option to change your flight if the capacity of the plane reaches 70%. The FAA has a list of the major airlines and their COVID-travel related policies.

The airlines that restrict onboard capacity during this time, especially if you are in a region where case numbers are high, are the ones you want to use for your travel where possible.

There are also two pretty scary videos circulating online with someone sneezing and someone coughing, on a plane. The animations show that the lighter respiratory droplets circulate in the cabin and then begin to diminish from filtration. However, someone sneezing will be wearing a mask, and while the inside of their mask will look like a scene from Ghostbusters, far fewer droplets will circulate in the plane than these animations show with an unmitigated blow. Remember, it is exposure to infectious material over a prolonged time that a concern, and the air-filtration on a plane is your friend.

Airline travel during this time seems worrying, and before going ahead you have to assess all factors into determining whether you fly or not. If you are in the high risk group for developing severe COVID-19 symptoms, then despite all the precautions you and the airline can take, it is unwise to get on a plane. For us, given the prevalence of COVID-19 in my area (very low at the time), and the prevalence in Australia (very low), we assessed that the risk of infection was low. Knowing the risks and being armed with a plan that would reduce our interactions and exposure during our travel helped us tackle this trip in the safest way we could.

Additional suggestions I have received from comments (I will update as we go):

• Bring your own snacks, rather than risk fomite transfer from cabin crew. Anything that lowers interaction is a plus.

• Business or 1st class reduces the number of people around you.

• Wipe the nozzle before adjusting!

• Window seats result in fewer interactions than an aisle seat - get a window seat if you can.

Erin S. Bromage, Ph.D., is an Associate Professor of Biology at the University of Massachusetts Dartmouth. My research focuses on the evolution of the immune system, the immunological mechanisms responsible for protection from infectious disease, and the design and use of vaccines to control infectious disease in animals. My research also focuses on designing diagnostic tools to detect biological and chemical threats in the environment in real-time. For more information on the author and the origins of these blogs, please read here.

***Please note: I did reach out to Qantas, United, and Delta to get more information from them about air filtration onboard their planes. They did not respond. :(