Hospital administrators should take a new look at copper, new research suggests, with evidence emerging that the metal can halt the spread of a wide array of diseases.
Long before Pasteur invented the germ theory of disease, copper, and alloys such as brass, were touted as protectors against ill health. While many such pre-scientific remedies have failed rigorous testing, copper has been demonstrated to be a powerful antibiotic.
Despite the pervasive myth that antibiotics fight viral diseases like flu, effectiveness against bacteria normally provides no indication of anti-viral properties. However, Warnes reports that copper kills coronaviruses, a category that includes severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS).
These diseases are often resistant to human-to-human transmission, but can be very long-lived when shed by animal hosts, allowing them to be picked up by humans touching surfaces on which they have survived. “Pathogenic human coronavirus 229E remained infectious in a human lung cell culture model following at least five days of persistence on a range of common nonbiocidal surface materials, including polytetrafluoroethylene (Teflon; PTFE), polyvinyl chloride (PVC), ceramic tiles, glass, silicone rubber, and stainless steel,” the paper reports.
However, when Warnes and her co-authors used copper alloy surfaces, they found the viruses were quickly inactivated so they were no longer effective. Even a low concentration of copper proved “very effective,” in the authors' words, when mixed with zinc to make brass.
“Exposure to copper destroyed the viral genomes and irreversibly affected virus morphology, including disintegration of envelope and dispersal of surface spikes,” the paper reports.
The paper explores the reasons for the effect, which it attributes to a combination of copper itself and reactive molecules containing oxygen that are generated on the alloy surface.
Coronavirus 229E is one of the major causes of the common cold, and seldom fatal. However, it is part of the same family as SARS and MERS, which have killed over 1,000 people between them. While researchers naturally prefer to work with a virus that causes colds than its more deadly relatives, they hope their discovery may prove more widely applicable.
A previous paper by two of the same authors showed that copper also kills the MNV-1 virus, part of the norovirus family responsible for roughly half of gastroenteritis cases. However, alloys containing over 60 percent copper were required in that case, higher than for coronavirus 229E. Where sewage and plumbing is well developed gastroenteritis is generally associated with a day or two hunched over a toilet and some unintended weight loss, but worldwide it kills millions of people a year. Since noroviruses and coronaviruses are not closely related, copper's effectiveness against both suggests its applications may be widespread.
The authors recommend using copper alloy surfaces in places where diseases are likely to spread, such as the communal areas of hospital respiratory disease wards.