US Pharm. 2020;45(4):28-32.

The novel coronavirus SARS-CoV-2 that causes COVID-19 is now likely to become the fifth endemic coronavirus in humans. Scientists are working to decipher its genome to help us stop other coronaviruses entering the human population.

How the novel coronavirus that causes COVID-19 made the leap from animals to humans is a puzzle that scientists are trying to solve as humanity comes to grip with the deadly pandemic sweeping the globe. At the frontline of this scientific work is Professor Edward Holmes, an evolutionary virologist who holds a joint position with the School of Life and Environmental Sciences and the School of Medical Sciences at the University of Sydney, Australia.

He has been working closely with scientists in China and around the world to unlock the genetic code of SARS-CoV-2, the virus that causes COVID-19, to understand its origins and assist in the race other scientists are engaged in to find an effective vaccine. Their work will also help in the monitoring and prevention of other viruses that could potentially transfer from wildlife into humans, causing what are known as zoonotic diseases.

Already this year, Professor Holmes has coauthored several papers on the novel coronavirus, including two of the earliest descriptions of the virus (published in Nature and The Lancet).

Published by Nature, the first paper identifies a similar coronavirus to the one now infecting humans in the Malayan pangolin population of southern China. Professor Holmes, a coauthor, is the only non-China–based academician on the paper. Understanding the evolutionary pathway by which this novel coronavirus has transferred to humans will help us not only combat the current pandemic but will assist in identifying future threats from other coronaviruses in other species. This paper is an important part of solving that puzzle.

Professor Holmes said, “The role that pangolins play in the emergence of SARS-CoV-2 (the cause of COVID-19) is still unclear. However, it is striking that the pangolin viruses contain some genomic regions that are very closely related to the human virus. The most important of these is the receptor-binding domain that dictates how the virus is able to attach and infect human cells.”

The paper identifies pangolins as possible intermediate hosts for the novel human virus that has emerged. The authors call for these animals and others to be removed from wet markets in order to prevent zoonotic transmission to humans.

Scientists and medical experts do not possess a good understanding of which virus characteristics and environmental factors control virus persistence in the environment, for example, in aerosols and droplets, on surfaces including skin, and in water, including seawater, according to Drs. Boehm and Wigginton. “When a new virus emerges and poses a risk to human health, we don’t have a good way of predicting how it will behave in the environment,” Dr. Boehm said.

In their paper, Drs. Boehm and Wigginton address potential threats that viruses such as SARS-CoV-2 pose to water sources. We usually only worry about viruses in water if they are excreted by humans in their feces and urine. Most enveloped viruses are not excreted in feces or urine, so they are not usually a first thought when it comes to our water sources. There is increasing evidence that the SARS-CoV-2 viruses, or at least their genomes, are excreted in feces. If infective viruses are excreted, then fecal exposure could be a route of transmission, according to Dr. Boehm, who added, “It’s unlikely this could be a major transmission route, but a person could potentially be exposed by interacting with water contaminated with untreated fecal matter.”