Doctors and nurses today continue to get infected while treating covid patients because they rely on apparel that was never designed for Infectious Disease defense.
Most American health care workers in 2020 wore surgical apparel in covid hospitals. Infectious Disease PPE and Surgical apparel are somewhat opposites. Surgical apparel prevents a doctor’s dust and germs from reaching a patient’s open wound or site, intending to create a sterile zone and avoid patient infection. Infectious Disease apparel defends the opposite direction: a patient’s germs from reaching a doctor. Let’s expand upon these differences and see why surgical apparel is so woefully inadequate for protecting doctors and nurses against covid.
A warning: reading the below will completely change how you view images of the outbreak. The images of a pandemic are so often the health care workers dressed in surgical apparel – yet, in a few paragraphs, you will understand how inadequate that apparel remains, look at pandemic pictures in a new light, and feel an added swell of sympathy for health care workers.
Back to surgical apparel: the primary goal of surgical apparel is to create a sterile environment for a patient. This just does not matter for Infectious Disease defense. Creating a sterile environment for a patient’s open hip or shoulder does little to protect a doctor or nurse's eyes.
The primary goal of Infectious Disease PPE is to prevent wearer contamination and infection. To this end, protecting the mucous membranes – the eyes, nose, and mouth – becomes a priority for Infectious Disease PPE, especially when covid becomes aerosolized. Most surgical gowns protect none of the mucous membranes. Read that again. To make up for this complete lack of protection, health care workers then turn to the shelves and patchwork pieces to compensate for the failure of surgical apparel: N95 masks, face shields, etc.
Using a face shield to defend its wearer from aerosols is utter nonsense. Aerosols can easily travel around a face shield. We can make a 4000-pound airplane fly – making 5 micrometer particles dance and turn corners is trivial. Here are two proofs of face shield futility for the non- fluid dynamics engineers. First, stand behind a 1967 Ford Mustang, wear a face shield, and test whether one can smell unburned gas in the exhaust. Of course one can. Note: the gasoline was a liquid before it was heated. Epidemiologists for years have used a droplet/airborne dichotomy based on virus particle size as a predictor of disease virulence, which may work fine for epidemiological modelling. For PPE and the rest of the mechanical world, however, the droplet vs airborne differentiation based on particle size is a false dichotomy since there are 7-8 variables who together determine whether an object stays airborne and how it travels (including around a face shield): particle size, pressure above the airborne object, pressure below/left/right, air flow speed, temperature, humidity, air density, gravity (albeit a constant), and object shape. Every breath that a person draws beneath a face shield creates a negative pressure to pull aerosols around and under the face shield (although an N95 mask will blunt the inhalation's negative pressure spike, any leak in the mask negates this); the point is … the eyes behind a face shield get exposed with each inhalation, covid ocular infection was proven in March 2020, and contaminated air will linger behind the face shield between breaths. As a second demonstration of face shield futility, kindly see this Israeli study, which showed that 7 out of 8 health care workers had contaminated skin after using a face shield, and that was only twenty minutes and two patients. Imagine how much more contamination exists after a real nursing shift of 8-12 hours and 15-30 patient visits. Then add a leaky patient ventilator mask (see side picture from Toronto in 2003) or two (this CDC graphic shows how common leaks are) and its pressurized and turbulent plume, and a face shield offers little protection for health care workers treating patients. A face shield could not even protect its wearer from a sneeze in this study, which did not even model the added effects of wearer inhalation.
Doffing is a common source of wearer self-contamination and infection. Watch dozens of health care workers doff soiled protective apparel, and one will see countless self-contaminations. This is especially problematic for surgical apparel, which was never designed for safe doffing. There are so many problems with surgical apparel doffing that I will save this expansion for a separate blog.
The popular yellow gowns are nothing more than PPE theater. They are inexpensive, abundant, and pretty much useless for Infectious Disease defense. As mentioned above, they do nothing for the mucous membranes. Do they protect any other body parts? No. A barrier material used in Infectious Disease defense must pass ASTM 1671, which certifies that the materials used in protective clothing are resistant to penetration by pathogens. If the yellow gowns do not even resist viral penetration, then what good are they?
Worse, surgical gowns are often called “isolation gowns.” This must stop in the context of Infectious Disease PPE. It is misleading. “Isolation gown” is a surgical apparel term for sterile garments that protect a patient from a doctor's germs or dust. Most do not pass ASTM 1671 and protect the doctor; such garments are not “isolation gowns” in the context of Infectious Disease PPE, and only create a false sense of security.
The yellow gowns attained widespread usage simply because of a failure to stockpile real Infectious Disease apparel before covid. The ensuing PPE shortage ushered many problems. The most obvious was thousands of infected, sick, suffering, and dead health care workers. The most subtle was a reduction in acceptable standards of what constitutes adequate Infectious Disease PPE. When one is starving, anything looks edible.
Given all these problems with surgical gowns, one must ask: why are we using surgical apparel in an Infectious Disease outbreaks? The simple answer is that the surgical products were on the shelf when the outbreak started, and remain what the manufacturers make profitably and at scale. Surgical products have been a constant supply item for every hospital for decades, so naturally the manufacturers were quick to dovetail an old product into a new market, and PPE buyers quickly achieved "better than starving" status. The deeper answer is that not enough people cared about Infectious Disease PPE before covid-19. There were spurts of interest after 2003 and 2014, but nothing sustained, and certainly not enough financial interest to propel long term supply. This changes in 2021 given covid’s economic devastation.
Optimized Infectious Disease PPE is commercially available now. There are better options than surgical apparel. And for health care workers' sake, please stop conflating the two.
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Will has been developing PPE for Infectious Disease defense since 2003. He's worked with PPE experts and health care workers everywhere from Toronto to Geneva, Atlanta's CDC, Singapore, Korea, Stanford U, Manhattan, Cleveland, countless hospitals, and a most memorable Panera Bread in Pittsburgh. Here are some lessons and stories from the journey.