Ruminations of an idle surgeon: the sequel
I have fielded lots of questions about face masks and their suitability for containment of the novel coronavirus. Unfortunately, we started off on the wrong foot with masks and we are now paying the price. Let me explain.
The issue of non-healthcare personnel wearing face coverings in public as a mitigation strategy during the Covid-19 pandemic was needlessly muddied by organisations such as the Centres for Disease Control and Prevention and the World Health Organisation, and indeed by many health professionals in general, myself included.
We took a stance, well-intentioned as it might have been, that was based purely on our understanding of mask use in the patient-care setting. As healthcare workers, we are taught how to use a variety of masks for different risk settings, with the gold standard being the “fit-tested” N95 respirator.
We based our advice on the certain knowledge that the public at large could in no way be properly fit-tested, would not have the practice and knowledge of proper mask wear and handling, and would deplete the limited supply of personal protective equipment that was in such short supply for health workers.
We were wrong; we were thinking about the healthcare setting and not about the community setting. Mitigation strategies to “flatten the curve” are key to controlling a pandemic, and we now know with a high degree of certainty that any face-covering goes a long way to achieving mitigation; certain Asian countries have known this for quite some time.
Numerous studies have now demonstrated that a face-covering that goes over the nose and mouth reduces transmissibility by minimising dispersal of infected droplets when we breathe, speak, yell, cough or sneeze by 70 per cent to 80 per cent.
Cloth face-coverings do not afford perfect protection against the virus, but this is a case where we must not let “perfect” be the enemy of “good”. Furthermore, this may be a good time for policymakers to resort to the “precautionary principle”, a strategy for approaching issues of potential harm when extensive scientific knowledge on the matter is lacking; we have little to lose and potentially something to gain from this measure.
A recent study by Dekai Wu, the Professor of Computer Science and Engineering at the University of California, Berkeley, showed that if 80 per cent of a population were to don a mask, Covid-19 infection rates would statistically drop to approximately one twelfth the number of infections.
The following CDC recommendations on masks seem to be very good advice:
• Cover your mouth and nose with a cloth face cover when around others, as you could spread Covid-19 to others even if you do not feel sick
• Everyone should wear a cloth face cover when they have to go out in public — for example, to the grocery store or to pick up other necessities
• Cloth face coverings should not be placed on children under age 2 or on anyone who has trouble breathing or is unconscious, incapacitated or otherwise unable to remove the mask without assistance
• The cloth face cover is meant to protect other people in case you are infected
• Do not use a face mask meant for a healthcare worker
• Continue to keep about six feet between yourself and others. The cloth face cover is not a substitute for social-distancing
Note that the latest WHO recommendations differ slightly from the CDC ones primarily because the target audience for the WHO includes countries where universal mask-wearing is not possible and where PPE for healthcare workers is in very short supply.
I am not quite sure when I will be getting on an aircraft again but it is worth giving some thought about what travel will be like when flights do resume.
First, you should know that nearly all American and European airlines now require that passengers and crew wear face masks. Many will soon be introducing more thorough and presumably fashionable PPE for cabin crew. Also, the Transport Security Administration is now allowing one liquid hand sanitiser container up to 12 ounces per passenger — previously a maximum of 3.4oz — in carry-on bags until further notice.
Many people have asked me how safe aircraft cabin air is. I, like most, have always thought that the air had to be stale and surely the source of the germs that often make you sick when travelling. Turns out that’s not quite the case.
Aircraft ventilation systems were developed in the era when smoking was permitted on board. These ventilation systems are therefore robust and super-efficient. Although there is some variation between aircraft manufacturers, most modern aircraft use similar ventilation systems.
The aircraft is usually divided in sections of five to seven rows, with each section becoming its own ventilation compartment. Air circulated in the aircraft is a 50:50 mixture of the pure, sterile outside air and air recirculated from the cabin. The cabin air is forced through high-efficiency particulate air filters 25 to 30 times an hour. These filters capture 99.97 per cent of all particles larger than 0.3 microns. The 50:50 mixture of filtered air enters the cabin where the side wall meets the roof and exits below the windows near the floor.
The entire volume of air in each section is exchanged 12 to 15 times an hour, which is equivalent to the air exchanges we have in modern operating rooms. The air coming out of the overhead nozzle is directly from the Hepa filter and so can act as an invisible envelope of super-clean air when aimed at your face.
Can you still catch something when you’re on a flight? Of course, but the point here is that the circulated air likely will not be the source. You can become infected if a sick passenger coughs or sneezes in your direction, or if you touch a contaminated surface and then touch your mouth, nose or eyes.
Strategies you can use to minimise the risk of getting sick include wearing a mask and wiping down all surfaces in and around your seat with disinfectant wipes. Some experts say that the window seat is safer because it exposes you to less people traffic. Having an empty seat beside you is ideal, but not always possible.
Take along your own snacks and drinks to reduce interactions with cabin crew and try not to use the washroom unless you really need to, as most surfaces are contaminated and the violent negative pressure flush creates aerosol.
Airlines are developing new methods to improve passenger safety. In the near future, we may be subject to health checks upon arrival at the airport — ie, think rapid ribonucleic acid tests, temperature checks and immunity passports.
Some airports are trialling “sterilisation” booths, which expose passengers to an antimicrobial fog. All carry-on and checked luggage are likely to undergo disinfection. Trays at security will be disinfected between each use. Aircraft cabins may be subjected to ultraviolet sterilisation between flights and washrooms between each use.
Long-acting, antimicrobial surface coatings are being developed for airports and aircraft cabins. In addition, newer aircraft such as the Boeing 787 Dreamliner have introduced changes that result in a much healthier environment for the passenger by decreasing the cabin pressure and increasing the humidity level. (Dry mucous membranes make you more susceptible to infection.)
The Situation in Bermuda
So how are we doing here in Bermuda? The short answer is “Really, really well!”
We are in the category of “local transmission with clusters of cases” and have no community spread. Our seven-day, real-time reproductive number at the time of writing was down to 0.63, which means we’ve got this thing under pretty good control.
Kudos to David Burt, the Premier, health minister Kim Wilson, Cheryl Peek-Ball, the Chief Medical Officer, and the Epidemiology and Surveillance Unit for the sterling job they have done. They have let themselves be guided by the science and have based their actions on the data.
One last bit of advice: please take Covid-19 seriously. This is not the flu, as most have begun to realise, and it is very likely that we’re stuck with it for a very long time. We will have to incorporate changes in our daily lives and likely learn to live with this virus as the “new normal”.
Let’s not let our guard down. Keep well and stay safe.
• Links to mask recommendations: https://www.who.int/publications/i/item/advice-on-the-use-of-masks-in-the-community-during-home-care-and-in-healthcare-settings-in-the-context-of-the-novel-coronavirus- (2019-ncov)-outbreak; https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/diy-cloth-face-coverings.html
• Joseph Froncioni is an orthopaedic surgeon
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