**This post was first published on March 11, 2020 and last updated on October 25, 2020 at 10:15pm PDT. It will be updated as more science and research becomes available.**
Research has shown that copper has anti-bacterial and anti-viral properties which make it more resistant to COVID-19 than other materials. In this post, we comprehensively discuss all available research and studies.
Please note that there is no scientific evidence to suggest, and we do not suggest, that copper or copper-based products are effective in preventing COVID-19 infections or reducing the likelihood of such infections. This article is focused solely on scientific evidence which indicates that copper as a material has anti-bacterial and anti-viral properties.
General Research and Studies
The effect of copper on bacteria and viruses has recently been the subject of a number of articles, including in Fast Company, Dwell, Vice, Cleveland, Smithsonian, and The New York Times. These articles are all in reaction to a number of recent studies which have explored the properties of copper which make it more resistant, as a material, to the coronavirus. The Washington Examiner also recently published an opinion piece from a well-known professor of economics who persuasively made the case for greater use of copper to help slow the spread of future pandemics.
The anti-bacteria and anti-viral nature of copper was discovered long before the outbreak of the coronavirus. It was discovered centuries ago by ancient civilizations which led to the use of copper in various health applications, including in water vessels to purify drinking water. In modern times, copper has been the subject of numerous studies by the scientific community as well as attention from the World Health Organization.
In one recent study, which was published in the Journal of Health, Population and Nutrition, scientists studied the effect of storing water in a copper pot on microbially-contaminated drinking water, including harmful bacteria such as e. coli, salmonella typhi and vibrio cholerae. In particular, scientists stored water contaminated with this bacteria in copper pots for 16 hours at room temperature. The bacteria was no longer recoverable when the researchers examined it, which was an incredible result compared to water stored in control glass bottles under the same environment (in which the bacteria continued to grow and flourish). The bacterial situation was even worse in reusable plastic bottles.
In another recent study, scientists again studied the effect of storing water in a copper pot on water contaminated with bacteria. In this study, the scientists incubated water with a colony of harmful bacteria and then stored the water overnight at room temperature in both copper pots and glass bottles. In the morning, the bacteria was no longer recoverable from the water that had been stored in the copper pots, although it was recovered from the water stored in the glass bottles.
In yet another recent study, researchers stored water contaminated with bacteria in a variety of different water containers, including copper and silver containers, in order to determine their efficacy at removing biological contamination from drinking water. The study revealed that the copper vessels had a significant inhibitory effect on the bacteria in the water after only a few hours of exposure.
In addition, in 2008 the United States Environmental Protection Agency published a study showing that copper surfaces are proven to continuously reduce bacterial contamination and provide continuous antimicrobial action even with repeated exposures. The study also found that copper surfaces continuously kill over 90% of bacteria after repeated exposures during a day, prevent the buildup of disease-causing bacteria, and deliver continuous, long-lasting antibacterial activity.
These and other similar studies confirm long-standing anecdotal evidence linking exposure to copper with resistance to infection. The first recorded medical use of copper appears in the Smith Papyrus, written between 2600 and 2200 B.C. This ancient text said that copper could be used to sterilize wounds and drinking water. In addition, it has been said that ancient civilizations in Egypt and Babylon observed that soldiers found scraping their bronze (an alloy of copper and tin) swords into wounds would tend to be more resistant to infection. In addition, storing water in copper vessels has long been utilized as a practice in India to eliminate microbes from drinking water.
More recently, in the 19th century, during an epidemic of cholera (a bacterial disease) which was spreading through France, a French doctor noticed that laborers at a copper smelter in Paris were not becoming infected with cholera. He observed that the same was true of other people in the city that worked with copper, including jewelers, goldsmiths and boiler makers. That epidemic ended up killing more than 6,000 people out of a population of approximately 1.6 million, reflecting a ratio of approximately 0.4 percent. However, only 45 of the people that worked closely with copper died, representing a ratio of only 0.05 percent.
Research Specific to Coronavirus 229E (HuCoV-229E)
In addition to the above-noted research, there was also a study on the effect of copper specifically in respect of coronavirus 229E (HuCoV-229E), which is distinct from COVID-19.
The study, published by the Centre for Biological Sciences at the University of Southampton in the United Kingdom, found that coronavirus 229E (HuCoV-229E) persisted in an infectious state on common surface materials for several days. However, when the surface material contained copper, the scientists observed rapid inaction of coronavirus 229E (HuCoV-229E).
In particular, scientists found that coronavirus 229E (HuCoV-229E) was rapidly inactivated on copper surfaces, with the inactivation rate being roughly proportional to the percentage of copper in the metal surface. In particular, metal alloys containing 90% copper were found to inactivate the virus in 30 minutes or less. The researchers provided the following chart to summarize the impact on coronavirus 229E (HuCoV-229E) by reference to the percentage of copper in the metal surface ("Cu" refers to copper content). The vertical axis represents the amount of virus left on the copper surface:
The researchers concluded that copper surfaces could be employed in communal areas and at any mass gatherings to help reduce transmission of respiratory viruses from contaminated surfaces and protect the public health.
Research Specific to COVID-19
More recently, on March 17, 2020, a new study was released concerning COVID-19 by the National Institutes of Health, CDC, UCLA and Princeton University scientists in The New England Journal of Medicine. The scientists examined the length of time for which specifically COVID-19 could survive on various materials, including aerosols (air), cardboard, plastic, stainless steel and copper. The study concluded that while the coronavirus could survive for up to two to three days on plastic and stainless steel and up to 24 hours on cardboard, it could only survive for up to four hours on copper. This study further confirms the anti-viral nature of copper.
The results of this study can be simplified as follows:
This study has also received attention from The Economist, which published the following helpful summary chart comparing (in a more complex manner) the longevity of the coronavirus on copper as compared to the other materials:
In another study, scientists found that the coronavirus was rapidly inactivated within a few minutes by copper surfaces.
Given this research, one may wonder why copper is not more actively used for surfaces in public places, including hospitals. In fact, in one study, scientists concluded that the use of copper surfaces could reduce bacterial and viral infection rates in hospitals by 58 percent. Although most hospitals have not yet adopted this approach, it appears to have significant potential. The following photograph of an intensive care unit in a hospital, care of the Medical University of South Carolina, illustrates the locations in which copper could be used as a surface in a hospital to minimize the spread of infections:
This body of research has recently inspired health sciences researchers at the University of Arizona to study whether or not certain copper-based chemical compounds could potentially stop the virus that causes COVID-19.
How Does Copper Kill Bacteria and Viruses?
The special effects of copper can best be analyzed through the lens of both chemistry and biology. When bacteria or viruses come into contact with copper, they absorb copper ions, which are essentially electrically charged particles.
These copper ions, through a process known as the oligodynamic effect, essentially punch holes into the membranes (walls) of the bacteria and viruses. Once the membrane is damaged, the copper ions move inside and destroy the DNA and RNA, preventing the bacteria and viruses from further multiplying. Interestingly, bacteria have both DNA and RNA while viruses have only RNA. However, notwithstanding that difference, the effect of the copper ions is essentially the same.
The following diagram, courtesy of the American Society of Microbiology, offers a more detailed depiction of this process. Portion "A" of the diagram depicts copper dissolving from the copper surface and copper ions causing damage to the membrane of the bacteria/virus. Portion "B" depicts the membrane rupturing as a result of the copper ions, causing damage to the bacteria/virus. Portion "C" depicts the copper ions inducing the creation of reactive oxygen which may cause further damage to the membrane. Portion "D" depicts the DNA/RNA within the membrane becoming damaged and inactivated.
In one leading study, cells of e. coli were exposed for 1 minute to a copper surface, a normal non-copper surface, and a stainless steel surface. The study showed that cells exposed to the copper surface suffered membrane damage and quickly became immobilized. The following microscopic images from the study show the result. Live bacteria with intact membranes are green, while those with damaged membranes are red:
Business and Government Start Considering Greater Use of Copper
As discussed in Forbes, this compelling research on the anti-bacterial and anti-viral properties of copper has led the medical industry to rush to create and manufacture specialized face masks made with copper. In addition, engineers have developed a process which is capable of spraying a thin layer of copper on door-handles and doorknobs.
Other recent investigations have demonstrated that the speed of copper's anti-bacterial and anti-viral effects can be accelerated if the copper is shaped in a way that maximizes the surface area of copper which makes contact with the bacteria or virus. It is for this reason that some businesses have started producing copper designed with a hammered or otherwise uneven texture to maximum surface area.
In addition, some governments have begun to consider the possibility of using copper in public areas in order to minimize the spread of infections. For example, a New York State Assemblywoman recently introduced a bill that would require publicly funded construction projects to use copper. The bill would require all new construction projects receiving state funding to use copper alloy touch surfaces – including door handles, bathroom fixtures, bed rails and handrails. It has been said that the legislation would reduce the spread of infection and help boost the local economy by investing in locally made materials.
The Problem with Normal Reusable Water Bottles
As research studies have shown, ordinary reusable water bottles can become environments that are prone to cultivating harmful bacteria and viruses. At this time, we are not aware of any studies specifically focused on copper water bottles and COVID-19.
As we use our water bottles throughout the day, they repeatedly come into contact with our hands, and thereby become covered in bacteria and potentially viruses. While the same is true of many other things (such as our smartphones), water bottles are more problematic because we put them to our mouths and drink from them. While it may be difficult to think about, the reality is that we put something covered in germs to our lips multiple times each day.
This problem is aggravated by the way that most reusable water bottles are designed. Often, we carry our water bottles by holding them by their caps or lids. This means that our hands come into contact with the lip of the bottle, which ends up touching our mouths when we drink from it.
Even if our water bottles are designed differently and we wash our hands multiple times per day, droplets floating in the air containing bacteria and viruses (from other people that may have coughed or sneezed) can land on our water bottles. We can then become infected by those same bacteria and viruses when we drink from our water bottles.
In addition, there is plenty happening inside most reusable water bottles which is concerning. As studies have shown, there is a significant link between reusable water bottles and the growth of bacteria colonies. In short, since the nature and function of reusable water bottles involves moisture, they become breeding grounds for bacteria and viruses.
This problem can be further aggravated by the way that we refill our water bottles. For example, if we use a water dispenser or water fountain at the workplace, gym or in an airport, there is a very good chance that bacteria or viruses left by someone else who used that water dispenser or water fountain before us will find their way into our water bottle, contaminating the bottle and the water in it.
As demonstrated by various research studies, copper naturally and safely kills bacteria and viruses through a natural process. As mentioned above, copper has been used for thousands of years to sterilize contaminated water naturally and safely. However, please note that there are no studies of which we are aware that examined copper water bottles and COVID-19.
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Lastly, please note that there is no scientific evidence to suggest, and we do not suggest, that copper or copper-based products are effective in preventing COVID-19 infections or reducing the likelihood of such infections. This article is focused solely on scientific evidence which indicates that copper as a material has anti-bacterial and anti-viral properties.
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About the Authors: This article was collaboratively written by our team of researchers and writers with the benefit of all available scientific studies and other relevant literature. Our team of researchers and writers include experienced health researchers including a qualified medical professional. Please note that information in this article is not intended or implied to be a substitute for professional medical advice, diagnosis or treatment.