Myth: Antibacterial Soap Works Against SARS-CoV-2.
Truth: It Doesn't.
Likely the single most reported preventative measure against the spread of COVID-19 has been frequent and thorough hand-washing. Even in March, before facemasks were found to be highly protective against COVID-19, hand-washing was seen as a major part of keeping healthy. Throughout the pandemic, but especially in the face of product shortages in the early months, consumers have been looking for anything that can give them an edge over the virus beyond hand-washing and mask-wearing. Many have turned to antibacterial soap, thinking that although the virus that causes COVID-19 is, well, a virus, it might be just slightly more effective than regular soap. It’s not (1).
Most antibacterial soaps use an antibacterial agent called Triclosan. Triclosan is a small molecule that targets an enzyme in bacteria called Enoyl-acyl carrier protein reductase (2). In simpler terms, it plays an essential role in bacterial growth. By binding to this enzyme, Triclosan prevents it from behaving properly and renders the bacterium useless. Humans do not have this same enzyme so there is no opportunity for the antibacterial soap to be harmless to us. Unfortunately, neither do viruses. So, using antibacterial soap against SARS-CoV-2 is like trying to drown a fish - you are exposing the virus to agents that do not hurt them.
Fortunately, soap is all you need from the hand-washing station to clear off any coronavirus, alive or dead. Soap is a very simple cleaning product that is often used in introductory science classes to explain the properties of water-loving (hydrophilic) and water-hating (hydrophobic) molecules. Molecular attraction and repulsion are two of the most fundamental properties of the molecular world, and we can all visually understand this with the way magnets attract and repel each other depending on which sides are pointed towards each other. Molecules work in the same way with water - some are attracted to it, and some repel it.
Dirt, oil, bacteria, and yes, viruses, along with just about anything else you'd want to clear off your skin are hydrophobic. Soap is an amphipathic molecule, meaning it has one end that is hydrophobic and one end that is hydrophilic. When involved with hand-washing, the hydrophobic end of soap attaches to the hydrophobic dirt (or virus) particle, and the hydrophilic end of soap attaches to water. Many, many soap molecules attach to the virus particle and encase it in a bubble of sorts. Water, attracted to this soap bubble because of the hydrophilic soap ends, pulls the soap bubble, with the dirt (or virus) with it down the drain.
Just like that, the virus is gone. No, soap doesn’t kill it always. As the diagram above shows, soap can wedge itself into the virus's membrane and pull it apart. But more often, soap simply encases the virus in a bubble. As we know, viruses can’t really hold their liquor and so alcohol-based hand sanitizers have been employed at scale to provide another effective option. These should really only be employed on the go, when hand-washing is not an option. Although alcohol in the right dosage is 99.9% effective at killing bacteria and viruses, it’s easy to miss spots on your hands and so hand-washing is definitively more effective.
So, as our mothers have told us for decades, WASH YOUR HANDS!
Myth: Mouthwash can prevent COVID-19.
Truth: It can’t.
Using mouthwash is a good idea. Along with fresh breath, mouthwash helps to rid the mouth of leftover food particles and fights plaque and cavities. Mouthwash, however, does not prevent contracting COVID-19. A new study published by researchers at Cardiff University teases the attractive idea that mouthwash can kill the coronavirus “within 30 seconds.”(3) This study is massively misleading and harmful.
Most mouthwashes kill bacteria by using chemicals that disrupt the cell walls of bacteria. Bacterial cell walls are negatively charged, which is attractive to the positively charged chemicals (often a chemical called Chlorohexidine) that mouthwash contains. As a result of this attraction, the chemicals bind to the cell wall and cause it to rupture, leaking fluids out of the bacterial cell and causing death. In theory, this mechanism can reasonably be thought to work the same way with viruses; SARS-CoV-2 also has a negatively charged lipid cell membrane just like bacteria, so the same bacteria-killing chemicals in mouthwash may have a similar effect on SARS-CoV-2.
Unfortunately, in practice, mouthwash has no effectiveness in preventing COVID-19 (4). Even the bacteria-killing and plaque-reducing power of mouthwash is really only effective when it is used every single day, and the cumulative power of the mouthwash chemicals can be consistently applied in the mouth. When looking at individual doses of mouthwash, it is not significantly effective against bacteria because of how much is present in the mouth and the numerous nooks and crannies that are found throughout the oral cavity. There is no reason to think that mouthwash would be able to come in and in a few seconds, easily neutralize every last SARS-CoV-2 virus in the mouth.
However, even if mouthwash was able to kill SARS-CoV-2, it wouldn’t have much of an effect on preventing COVID-19. Why? Because we wouldn't have mouthwash in our mouths constantly throughout the day. The chance that the coronavirus enters your mouth immediately before you use mouthwash is, for all intents and purposes, zero. Even if you use mouthwash twice a day, the chemicals don’t stick around in your mouth waiting for the coronavirus to come. Furthermore, even if mouthwash was 100% effective at killing the coronavirus, and using it was timed perfectly when the virus entered the mouth, a significant amount of the virus would remain in the body in the nose, throat, and lungs.
No matter if scientists in Cardiff were able to demonstrate that mouthwash can kill SARS-CoV-2 in vitro (in a lab), mouthwash is not an effective preventative device against COVID-19 because of the infrequency of use, the inconsistency of killing-power, the unrealistic timing required, and the location of virus particles.
WEAR A MASK INSTEAD.
Myth: The common blue facemasks should be worn inside out for more effective prevention.
Truth: Wear your mask properly.
We’re all painfully familiar with the blue surgical facemasks that, for good reason, much of the population wears during the COVID-19 pandemic. These masks are popular because of their ability to be mass-produced and their relative comfort that sacrifices little ineffectiveness. Unfortunately, it is becoming more and more common to see the masks worn with the white inside layer worn outside, with the blue layer closest to your face.
On March 15, a Facebook user posted a picture of a sign at her doctor’s office that said the following: “White side out when you’re not sick and want to keep the virus out and blue side out to keep germs in when you’re sick.” Furthermore, even healthcare workers at the hospital I work at, desperate to do everything they can to prevent the contraction of the disease, sometimes wear the masks inside out. Unfortunately, this effort to be safer actual backfires - wearing the mask inside out makes the mask much less effective (5).
It all comes down to the structure of the mask. These common blue surgical masks have a three-layer structure. The blue outer layer is a fluid-repellent layer that reduces the chance that viruses can attach to the mask (when we expel viruses from our mouths they are coated in a liquid layer made of our saliva). The middle layer is a high-efficiency filter that does most of the work in keeping out viruses that might get past the hydrophobic outer layer. The white innermost layer is an absorbent layer that captures moisture coming out of the mouth.
Key to an understanding of why the innermost layer needs to be closest to the mouth and nose is an appreciation of the fact that even with masks, we all breathe the same air. The innermost layer of the mask serves to capture the virus particles shot out of our mouth and nose that we expel while we breathe, talk, cough, and sneeze. Our breath hits the absorbent layer and particles are captured. The rest of the now filtered air will come out of the top and bottom of the mask, and other people will inevitably breathe that in. The difference, though, is that the innermost layer acts as a filter and extracts most of the particles first that could contain the virus.
By reversing the order of the layers, our breath will instead hit the blue fluid-repellent layer which simply allows virus particles to bounce off the mask and travel up over the mask and down under the mask with the rest of the air. We essentially use the properties of the mask to hurt us by harnessing the repellent outer layer to let potential virus particles escape.
So, wear the mask as it is supposed to be worn: blue side facing out. Pinch the top of the nose, and stay healthy.
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