Copper has been used for three millennia for its natural antiviral and antibacterial properties and are effective in killing 99.9% of bacteria within 2 hours. Bronze, brass, cupronickel, copper-nickel-zinc amongst others are all alloys of copper that are also natural antimicrobial materials.
On copper surfaces, bacteria and viruses die. When a microbe lands on a copper surface, the copper releases ions, which are electrically charged particles. Those copper ions blast through the outer membranes and destroy the whole cell, including the DNA or RNA inside. Because their DNA and RNA are destroyed, it also means a bacteria or virus can’t mutate and become resistant to the copper, or pass on genes (like for antibiotic resistance) to other microbes.
Ancient civilizations such as the Egyptians and Babylonians from 2600 and 2200 B.C. knew about the properties of copper in warding off infection. Soldiers would use copper to sterilise wounds by putting shavings from their bronze swords into their wounds to reduce infection and speed healing.
Copper was also used to cure medical problems in ancient China and India and is an important component of Ayurveda medicine today. Hippocrates in Greece and the Aztecs used copper oxide and copper carbonate, combined with other chemicals such as sodium carbonate, olive paste and honey, to treat skin infections.
French wineries even applied copper sulphate and slaked lime, called Bordeaux mixture, to vines to prevent fungal attack.
During the 19th century, outbreaks of cholera hit Paris from 1852-1855, Victor Burq a physician discovered the link between the antimicrobial properties of copper and certain professions. There were no cholera deaths in jewellers, goldsmiths, boiler makers, musicians who played brass instruments in the army.
After extensive research he concluded to the French Academies of Science and Medicine in 1867 that “copper or its alloys, brass and bronze, applied literally to the skin in the cholera epidemic are effective means of prevention which should not be neglected.”
Today, we have insight into why a person handling copper day in and day out would have protection from a bacterial threat: Copper is antimicrobial. It kills bacteria and viruses, sometimes within minutes. In the 19th century, exposure to copper would have been an early version of constantly sanitizing one's hands.
All of these laboratory studies have been translated into the healthcare environment. When copper alloy is used on regularly touched surfaces in busy wards and intensive care units, there is up to a 90% reduction in the numbers of live bacteria on their surfaces. This includes bed rails, chair arms, call buttons, over-bed tables, IV poles, taps and door handles.
Copper alloy touch surfaces are now being deployed worldwide in airports, trains, train stations, busses, restaurant kitchens and gyms. The new Francis Crick Institute in London is kitted out in copper alloys, supporting its foresight and vision as a world-leading research centre for the public good.
Some common viruses have no vaccine available, such as the winter vomiting virus (norovirus), influenza, mutate so rapidly that it is difficult for vaccines to keep up – and they need to be reformulated annually. Copper surfaces however wipe them out regardless of year-on-year changes in the microbes.