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

Much remains unknown about how the virus that causes COVID-19 spreads through the environment. A major reason for this is that the behaviors and traits of viruses are highly variable—some spread more easily through water; others through air; some are wrapped in layers of fatty molecules that help them avoid their host’s immune system; while others are “naked.”

This makes it urgent for environmental engineers and scientists to collaborate on pinpointing viral and environmental characteristics that affect transmission via surfaces, the air, and fecal matter, according to Alexandria Boehm, a Stanford professor of civil and environmental engineering, and Krista Wigginton, the Shimizu Visiting Professor in Stanford’s Department of Civil and Environmental Engineering and an associate professor at the University of Michigan.

Drs. Boehm and Wigginton coauthored a recently published viewpoint in Environmental Science & Technology calling for a broader, long-term, and more quantitative approach to understanding viruses, such as SARS-CoV-2, that are spread through the environment. They are also principal investigators on a recently announced National Science Foundation–funded project to study the transfer of coronaviruses between skin and other materials, the effect of UV and sunlight on the coronaviruses, and the connection between disease outbreaks and virus concentrations in wastewater.

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.”