Aiming to safely simulate how SARS-CoV-2, the virus that causes Covid-19, can spread across surfaces in a hospital, researchers left virus DNA on the rail of a bed in an isolation room in a hospital. Within 10 hours, this surrogate genetic material had spread to 41% of the sites sampled around the hospital ward, from arm rests in a waiting room to children’s books and toys in a play area, according to the study. Published as a letter in the Journal of Hospital Infection, the study, by University College London and Great Ormond Street Hospital, found that after three days, the surrogate genetic material had spread to 59% of the sites. On the fifth day, it had fallen to 41% of the sites.
“The main takeaway message for nurses and physician assistants is that it is important to take extra care with hand hygiene and when using PPE (personal protective equipment),” senior study author Dr. Lena Ciric told Florence Health in an email interview. “In this case, the virus DNA moved from surface to surface due to touch. Changing gloves after seeing each patient is very important.”
To prepare the virus DNA, the harmless substance that they used in the study, the researchers artificially replicated a section of DNA from a plant-infecting virus that cannot infect humans. This was then added to water at a similar concentration to SARS-CoV-2 copies that were found in the respiratory samples of infected patients. This water was then placed on the rail of the hospital bed in a room that is normally meant for higher-risk or infected patients.
Of all the sites that tested positive for the surrogate genetic material, the highest proportion came from the immediate area around the bed, including a nearby room with several other beds. Clinical areas like treatment rooms also tested positive for the virus DNA. On the third day, some 86% of sampled sites in the clinical areas tested positive, and a day later, 60% of the sampled sites in the immediate bedspace area tested positive.
“Locating the surrogate DNA outside the isolation room highlights how easily surfaces play a role in transmitting infectious agents, even from rooms designed to help containment,” the study authors wrote.
Dr. Ciric, who is in the department of Civil, Environmental and Geomatic Engineering at University College London, notes the importance of cleaning surfaces. “A virus like coronavirus is removed easily with wipes and normal cleaning products,” she told Florence Health.
The letter in the Journal of Hospital Infection pointed out that although thevirus DNA was inoculated just once to one site, patients who are infected with SARS-CoV-2 can continually shed the virus through touching surfaces and coughing. “Healthcare workers cannot prevent the spread of the virus during aerosol-generating procedures (AGPs) and contact with infected patients unless strict hand hygiene, careful donning and doffing of personal protective equipment, and consistent cleaning is undertaken,” the letter said.
One caveat of the study is that although it shows how rapidly a virus can spread when it’s left on a surface, it can’t determine how likely it is that a person would actually get infected by the virus.
- Letter to the Editor: COVID-19 pandemic – let’s not forget surfaces. Journal of Hospital Infection.