Bursting Bubbles: How Hand Washing Kills Viruses
In your entire adult life, you have probably never been told to “Wash your hands” as much as you have over the past few weeks. Although as children we were constantly reminded to lather up our hands with soap after playing outside or stroking a stray cat, as grown ups we are pretty much left to decide when it is appropriate to wash our hands. Your hands are one of the main points of contact between your personal island and the outside world, meaning they are a primed to pickup a plethora of invisible organisms. From business handshakes to calling the elevator, your palms can catch and carry microorganisms such as bacteria and viruses from the world around us. And one rub of your eye or bite of a nail could lead to a direct inoculation of such species into your body. Despite the majority of microorganisms collected by your hands being benign, some nasty germs can be transmitted from a contaminated surface to your digits, and in recent news, this has been shown to be the case for novel coronavirus. Therefore, washing your hands with soap and water could be one of your biggest means of protection in the fight against an invisible killer.
How Viruses Work and The Novel Coronavirus
Viruses are tiny particles which need a host organism to survive. The aim of a virus is not to kill you, but to use your cells in order to copy itself & increase its numbers before spreading to a new host. Your body is packed with trillions of cells which make up all your tissues. Each cell is like a mini-machine which is kept up and running by thousands of different proteins. After getting into the boy, viruses enter cells and hijack the replication machinery needed to make cellular proteins, allowing the virus to copy itself over and over again, with new copies leaving the cell. Once a cell becomes overwhelmed with viral particles, it bursts open and these new viral particles can attack neighbouring cells to use their replication machinery. The bursting open of a cell normally results in its death, and the more dead cells in a tissue, the less well it functions.
The novel coronavirus (‘SARS-CoV-2’) responsible for causing a disease called COVID-19 acts exactly like any other virus; hijacking the cell’s replication machinery to increase its numbers. However, the specific cells vulnerable to attack by SARS-CoV-2 are those in the airway and lungs. This is because for a virus to enter a cell, it must be granted access from a protein on the human cell surface. Much like a body guard outside a bar, cells express proteins on their outer surface to interact with the outside environment and permit access to certain molecules. SARS-CoV-2 binds to a protein called ‘ACE2’, found in high numbers on lung and airway cells, and acts like a key in a lock. ACE2 grants the virus an inside pass to these cells and upon entry, SARS-CoV-2 can make a break for it and begin to replicate. The vulnerability of lung and airway cells to the SARS-CoV-2 virus explains two of the main symptoms of COVID-19; a dry cough and shortness of breath.
How Can You Catch Coronavirus and How Does Hand Washing Help Prevent Spread?
According to the World Health Organisation (WHO), SARS-CoV-2 is spread through respiratory droplets – a.k.a the particles released when a person coughs or sneezes. Droplets are heavy, so normally hit the ground within 1-2 metres on the individual releasing them (although these studies have not yet been performed on the exact droplets SARS-CoV-2 is carried in). It is believed the time droplets containing SARS-CoV-2 survive on different surface materials vary, but we can assume they do survive for a few hours on the majority. Therefore, the most likely ways you can ‘catch’ SARS-CoV-2 is by an infected person openly coughing (without tissue/elbow cover) within 1-2 metres of you or by you touching a surface contaminated with SARS-CoV-2 viral particles. The most effective ways to protect against droplet-transmitted diseases are to keep distant from infected individuals, catch coughs & sneezing into tissues and immediately discard, and to wash your hands after being out and about. Soap and water are two of the deadliest weapons in killing viruses and bacteria, and are more effective than alcohol-based hand sanitisers in completely removing pathogens from the skin.
How soap and water kill a virus is relatively straight-forward. Viruses consist of a membrane which protects the precious copying material required for the replication of the virus and this membrane is made up of lipids (fats). What lipids do not like is detergent, because this breaks apart the bonds between them. When soap molecules come into contact with lipid membranes, they edges themselves into the membrane and prize it open; like a crowbar cranking open a crate. Therefore, applying soap and water to hands contaminated with viral particles permits the breakdown of the membrane protecting the virus copying code. Once this membrane is broken, the virus is rendered ineffective as the membrane holds the ‘key’ to permit the virus entry into cells, meaning the copying material cannot get access to the host cells. The key with breaking down viral particles with soap and water is the time you have the soap on your hands for. You should aim for 20-30 seconds of lathering, covering all surfaces, before rinsing. This guide is a great one to follow (scroll down for pictures!)!
However, soap isn’t always to hand after you have touched a potentially-contaminated surface, and these are the most risky situations for disease transmission. The main entry routes a virus has into your body is through your eyes, nose and mouth, so if you cannot wash your hands after coming into contact with germ-infected material, the main thing you should avoid doing is touching your face. Face touching is a very automatic and unconscious behaviour, so training yourself to avoid brushing that hair off your forehead or rubbing your eye can be tough. But if your hands were visibly dirty, it is very easy to glue your arm to your side and not scratch that facial itch. As viruses and other microorganisms are invisible to the naked eye, a way to avoid face touching is to imagine the contaminant has a colour. Say you are on the subway and touch a pole, that colour (whichever you chose) transfers onto your hands and until your hands are scrubbed clean, the colour remains. Be overly cautious and assume the virus is on all public surfaces, and when you arrive home or to work, the first thing you should do is wash that colour away! This behaviour should prevent self-infection and the spread of the virus onto surfaces in your home, helping you to keep protected from contracting a potentially dangerous disease.
We are all in a pretty scary and uncertain situation right now, but the mains things we can do to stop further spread of this new virus is to stay at home and wash our hands properly. If done properly as a collective, these actions will really slow the spread of novel coronavirus and help take the weight off our over stretched healthcare services. Remember to lather up every time you get home before touching anything and avoid any face touching when you are out and about! We are all in this together and we will get through.
Julia (@julia.ravey.science) xoxo