How do you fight something you can’t see? That’s the question when it comes to the coronavirus crisis which currently has many of us holed up at home. Physical distancing is one important answer to preventing the spread of the virus, as avoiding catching it in the first place stops you from spreading it to others. But how can we take the fight directly to the virus?
First, the bad news. You’ve probably seen this virus referred to as ‘novel coronavirus’. This has nothing to do with long reads — it’s just another way of saying that it’s a type of coronavirus we haven’t seen in humans before. Coronaviruses are actually a big virus family, and some of them cause types of what we call the common cold. SARS-CoV-2 is the particular member of this family that’s causing this outbreak.
Anyway, because it’s a new virus, we don’t have a vaccine for it, and making vaccines tends to take a while. And we don’t have any proven treatments for it either (regardless of whatever claims to the contrary you’ve heard from random WhatsApp groups/social media/US presidents). This is why stopping the disease from spreading rapidly and overwhelming hospitals is currently our best bet.
Outside of the body, there are ways for us to destroy the virus and reduce our own chances of contracting it. To understand how these work, it’s useful to know about the structure of this particular virus. SARS-CoV-2 is a type of enveloped virus. This just means it’s got an outside layer around its genetic material. The outside layer is made of fat molecules and is one of the possible targets for destroying the virus. We can also target proteins in this layer, or even the genetic material itself.
‘Wash your hands for 20 seconds’ is a mantra you’ll have heard oft-repeated over the past month. That’s because it’s comfortably the best way to destroy the virus. Soap contains molecules called surfactants, which have two ends: one end dissolves really well in fats, while the other end dissolves really well in water. When these molecules come into contact with the fatty outside layer of SARS-CoV-2, they dissolve it and tear the virus apart.
All types of soap contain these surfactant molecules, so it really doesn’t matter which type you use. Some soaps contain additional antibacterial ingredients, but these are active against (you guessed it) bacteria, so they don’t affect the virus. The surfactant molecules these soaps contain still do the job, though.
If you want to delve deeper into the chemistry of soaps and surfactants, The Chronicle Flask has a great explainer of the history of soap and how it works. Soap and water isn’t just good for your hands — it’s also effective at cleaning surfaces, too, so you don’t need to rush out and buy any fancy surface cleaners.
Right, so soap is great. But what if you can’t wash your hands right away? If you’re popping to the supermarket to pick up your food shopping, you probably won’t have easy access to soap and a sink. This is where hand sanitisers come in — assuming you managed to get your hands on some before it seemingly sold out everywhere.
Firstly, it’s important to note that hand sanitisers are not all created equal. Alcohol-based hand sanitisers are the type that you want. There are non-alcohol-based sanitisers, but these have been shown to be less effective against viruses. The alcohol-based sanitisers, on the other hand, are effective against many types of virus, including SARS-CoV-2.
Another point is that they need to contain at least 60% alcohol. If you’re using it to clean surfaces, the CDC recommends that a minimum concentration of 70% alcohol is needed. The alcohol molecules are doing the dirty work here — they damage the structure of virus proteins, destroying the virus. In a double whammy, they also dissolve the fatty outside layer of the virus. There’s a whole graphic dedicated to how they work here.
Hand washing and alcohol-based sanitisers are the best options for destroying any traces of virus on your hands. For hard surfaces, you’ve also got a couple of other options which work in similar ways against the virus.
A bleach solution is very effective at cleaning hard surfaces. The Centers for Disease Control and Prevention (CDC) explain how to make a 0.1% solution from household bleach on their website. Bleach reacts with and destroys virus proteins and the virus genetic material. It’s important to spray it on the surface and then leave it to act for around 10 minutes for the maximum effect.
It’s also very important not to mix bleach with other cleaners. There’s no need to anyway, as it does a very effective job on its own. And if you do, there’s the risk of the cleaner reacting with the bleach and generating toxic chlorine gas. We’re trying to kill the virus here, not you.
A minimum of 0.5% hydrogen peroxide solution is also effective against viruses. It works in a similar manner to chlorine bleaches, reacting with and destroying virus proteins and genetic material. Similarly, it should be left to act for up to ten minutes. It’s also a good idea not to mix it with other cleaners, particularly those containing vinegar. Vinegar and hydrogen peroxide makes corrosive peracetic acid, and while this is also used in some cleaners, it’s not a good idea to mix it up like this yourself.
Really, the bleach and peroxide options are overkill. Soap and water will do an effective job on any surface you can clean with them. Soap’s less hazardous to work with, too, and can be easily used to regularly clean surfaces you touch frequently.
With all the above said, it’s disclaimer time. You could be washing your hands every five minutes, and cleaning the surfaces in your house on loop. It still doesn’t guarantee you won’t catch the virus. What we’re trying to do here is to decrease the risk of you catching it, but it’s very difficult to reduce that risk to zero.
But outside of the physical distancing you’re hopefully all practising, washing our hands and surfaces are the best direct action we can take to prevent the virus spreading. By doing so, we’re reducing the burden on our health services and hopefully helping save lives.
CORRECTIONS: The graphic and article originally stated that the minimum concentration of bleach was 10%. This has been changed to 0.1% hypochlorite for clarity. Both graphic and article have been amended accordingly.
A recent study has shown 0.5% peroxide solution to be effective against coronaviruses on surfaces. The figure in the graphic and article has been changed to reflect this.
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- WHO guidelines on hand hygiene in healthcare – World Health Organisation
- Guideline for hand hygiene in health-care settings – Centers for Disease Control and Prevention
- Show me the science – when & how to use hand sanitizer in community settings – Centers for Disease Control and Prevention
- Coronavirus: household cleaning products can kill the virus – an expert on which ones to use – L Ciric, The Conversation
- How we know disinfectants should kill the coronavirus – K Jansen, Chemical & Engineering News
- Cleaning and disinfecting your home – Centers for Disease Control and Prevention