How COVID-19 spreads in health care settings

Researchers are trying to better understand how COVID-19 spreads in health care environments. Texas A&M University School of Public Health professor and Director of the Program on Environment and Sustainability Virender Sharma, PhD, recently published an article on surface contamination and contact transmission of the novel coronavirus in the journal Environmental Chemistry Letters. Sharma and researchers from the Central Texas Veterans Health Care System, analyzed studies conducted on viral shedding by COVID-19 patients, specifically how long the virus can survive on surfaces and the sequence of contact events that can spread the virus from one surface to another within health care settings.

From the earliest stages of research, scientists concluded viral shedding occurs from both symptomatic and asymptomatic patients. Viral shedding is when an infectious disease is released from a host, making it possible to infect others. Awareness of a viruses’ viral shedding is critical to understanding how the disease spreads. Sharma’s team found several studies that concluded the SARS-CoV-2 virus that causes COVID-19 can survive on many different types of surfaces commonly found in health care settings.

Thanks to the mask mandate, many understand that COVID-19 can be spread through respiratory droplets that travel through an infected person’s cough or sneeze, or when they talk or sing. Now, it is recognized that aerosol transmission is another major factor of disease spreading. The air itself can remain contaminated, as well as the nosocomial objects in health care settings like bedrails and mobile medical devices. Building upon even more studies, Sharma and fellow researchers concluded evidence has shown that objects or materials such as clothes, utensils and furniture—known as fomites—can, too, carry the virus. These fomites can be contaminated by direct bodily contact, contact with body secretions or fluids, or respiratory droplets.

It is vital, especially for the safety protocols of health care workers, to understand this fomite transmission. It is likely that transiently contaminated hands of health care workers contribute to the viral spread. The studies analyzed in Sharma’s review reveal that a transfer of disease through a series of events, like touch from bedrail to patient to bedrail to doorknob, is very possible. Survival of the virus on copper surfaces was the shortest.

SARS-CoV-2 replicates in the upper respiratory tract, making it more transmissible than some other respiratory infectious diseases. A recent review estimated that up to 45 percent of infections come from asymptomatic patients. Both asymptomatic and symptomatic patients had several day periods of viral shedding, the median duration being 12-24 days. Some studies have begun to examine the possibility of viral stool shedding leading to sewage contamination as well.

Study reviews like this one emphasize the critical importance of regular and thorough decontamination processes for hospital surfaces. This factor will play a crucial role in the control and prevention of COVID-19.

– by Laura Larocca