Even in the world of medicine, what is old is new again.

Thousands of years ago, Egyptians used it to sterilize drinking water. Ancient Romans, Aztecs and Greeks also used it for medical treatments.

I am talking about copper.

The symbol for copper on the periodic chart for elements is Cu. If we are talking about germs that might mean Cu later! (C + u = "See you")

Copper kills many germs on contact. Now it is back in hospitals to do just that.

One of the major ways we get sick is we touch surfaces out in the world, many made of metal or plastic. These surfaces are covered with germs. Germs live on poles on a train or bus. They are found on doorknobs and handles.

This is especially true in hospitals.

Bill Keevil is a microbiologist at Southampton University in Britain. He is investigating the properties of copper that kill germs -- or as researchers call them, pathogens.

Keevil points to studies that compare infection rates at U.S. hospitals that use copper surfaces and those that do not.

"They found that copper alloys gave a 58 percent reduction in infection rate. So that showed, you know, that in the real world of a hospital environment, copper alloys do a great job (in preventing infection)."

In a study published in the journal mBio, Keevil and his team found that copper surfaces can quickly kill the coronavirus 229E.

You may not know coronavirus 229E by name.

But if you ever have had the common cold or the more serious pneumonia, you have been in contact with it.

The coronavirus 229E is also closely related to the pathogen that causes SARS and MERS.

Keevil explains that copper ions -- electrically charged molecules -- kill dangerous viruses by destroying their genetic material. Copper ions do this by interacting with oxygen and changing the oxygen molecules. As a result, the virus cells cannot mutate.

"Now these ions are able to punch holes in the cell's membrane, enter the cell and destroy their nucleic acid. So they are completely killed. There's no chance of mutation leading to resistance, and there's no coming back. So the chemistry is fantastic."

Keevil notes that ancient civilizations knew about the germ-killing properties of copper. However, they may not have understood the science behind it.

Researchers at the U.S. National Institutes of Health wrote on their website about the oldest recorded medical use of copper.

They say its use is noted in an Egyptian medical book written about 4,000 years ago.

The book describes how they used copper to sterilize wounds and drinking water.

Keevil says earlier generations of builders in the United States also knew this about copper. That is why copper alloys such as brass were often used in building materials.

But more modern builders stopped using copper and copper alloys. They cost more than other building materials.

However, Bill Keevil says copper could save hospitals money. He says their other costs of fighting infection will drop, including drugs for treatment.

More importantly, less people will get sick.

I'm Anna Matteo.

Jessica Berman wrote this report for VOA News in Washington. Anna Matteo adapted it and added some additional reporting for Learning English. Caty Weaver was the editor.

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sterilize – v. to clean (something) by destroying germs or bacteria

pathogen – n. medical : something (such as a type of bacteria or a virus) that causes disease

mutation – n. biology : a change in the genes of a plant or animal that causes physical characteristics that are different from what is normal

fantastic – adj. extremely good