Can you catch coronavirus (COVID-19) from contaminated surfaces?

Can you catch coronavirus (COVID-19) from contaminated surfaces?

Coronavirus (COVID-19) is thought to be transmitted primarily through respiratory droplets, which are produced when people speak, cough or sneeze.1

It is also thought that touching surfaces contaminated with the virus, and then touching your mouth, nose and (possibly) your eyes, could lead to transmission.2

This is why the government is encouraging increased handwashing through the pandemic, as well as the frequent cleaning of ‘high touch’ surfaces, like door handles, railings and light switches.

Scientists are still learning about the virus, and there’s some debate over the exact scale of transmission via contaminated surfaces. 

Some sources claim that the risk of transmission through inanimate surfaces is ‘very small’.3 Other scientists, such as Peter Collignon, from the Australian National University, have estimated that “probably around 10% of transmission is likely to be just hands and surfaces”.4

Although scientists disagree slightly on this, it’s safest to assume that contaminated surfaces do pose a potential risk of transmission.

An increased cleaning routine is a simple and straightforward way to minimise this risk. In fact, a study recently published in the Lancet suggested that “environmental contamination leading to SARS-CoV-2 transmission is unlikely to occur in real-life conditions, provided that standard cleaning procedures and precautions are enforced.”5

Once a surface is contaminated, how long can coronavirus survive?

A study carried out earlier this year estimated that coronavirus could survive for 2-3 days on stainless steel and plastic surfaces.6

A more recent study has suggested that, under certain conditions, it might be possible for the virus to survive for as long as 28 days on non-porous surfaces, such as glass, polymer banknotes, stainless steel, vinyl and paper banknotes.7

But why do these findings vary so much?

Put simply, these studies haven’t compared the virus under the same conditions. The most recent ‘28 day’ study looked at surfaces kept in complete darkness. This was to negate the effects of UV light, which is known to kill coronavirus.

The conditions of the experiment has led to some scepticism from scientists, who claim that the experiment’s conditions are not reflective of real-life scenarios. 

In reality, surfaces are often exposed to UV light from the sun. This is partly why outdoor settings are thought to be safer during the pandemic than indoor environments.8

The virus is also transmitted via human mucus, which in itself provides a ‘hostile environment’ for viruses to survive. Mucus, however, was not used as the vehicle for the virus in this study.9 

Given the differences between these lab conditions and real-life environments, it is unlikely that the virus would survive for as long as 28 days in most residential or commercial environments.

In practice though, this doesn’t make much difference to most of us - high-touch surfaces are used throughout the day, so even a 2 or 3 day survival time poses a risk of transmission. This is why it’s important to increase your cleaning frequency throughout the coronavirus (COVID-19) outbreak.

How should I be cleaning to prevent transmission of coronavirus (COVID-19)?

You should pay special attention to high-touch surfaces like light switches, door handles and stair rails.10

Thankfully, lots of regular household cleaning products are actually thought to be effective against coronavirus. Even using soap and water can be effective at breaking down the outer, fatty layer of the virus and the act of wiping alone removes a number of the germs from surfaces.

If you have reason to suspect that a surface has been contaminated, you should use a disinfectant product afterwards, to kill the remaining germs.11 

When choosing a disinfectant, look for something that kills ‘99%’ of bacteria and/or viruses. 

If you’re not able to buy a suitable product, you could make your own disinfectant using household bleach. We’ve published a handy guide to take you through this: How to make your own disinfectant.

People don’t always realise that different disinfectants have different ‘contact times’. This means they may need to be left on the surface for a certain period of time before they’re fully effective. You should always read the label on your disinfectant carefully to ensure that you’re using it effectively.

If you’re looking for more info on how you should be cleaning your home or office, make sure to check out our comprehensive guide to cleaning during the coronavirus (COVID-19) outbreak: Guide to home and office cleaning during the coronavirus (COVID-19) outbreak

References

1.https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/how-covid-spreads.html
2.https://www.health.harvard.edu/diseases-and-conditions/covid-19-basics
3.https://www.thelancet.com/pdfs/journals/laninf/PIIS1473-3099(20)30561-2.pdf
4.https://www.theguardian.com/world/2020/oct/12/virus-that-causes-covid-19-can-survive-up-to-28-days-on-surfaces-scientists-find
5.https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30678-2/fulltext
6.https://www.medrxiv.org/content/10.1101/2020.03.09.20033217v1.full.pdf
7.https://virologyj.biomedcentral.com/articles/10.1186/s12985-020-01418-7
8.https://academic.oup.com/jid/article/222/2/214/5841129
9.https://www.bbc.co.uk/news/health-54500673
10.https://www.gov.uk/government/publications/covid-19-decontamination-in-non-healthcare-settings/covid-19-decontamination-in-non-healthcare-settings, https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/cleaning-disinfection.html
11.https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/cleaning-disinfection.html