A new study has aimed to simulate how SARS-CoV-2, the virus that causes Covid-19, may spread across surfaces in a hospital. For safety, the researchers did not use the SARS-CoV-2 virus but artificially replicated a section of DNA from a plant-infecting virus, which cannot infect humans, then added it to a millilitre of water at a similar concentration to SARS-CoV-2 copies found in infected patients’ respiratory samples.
The result: the virus DNA left on a hospital bed rail was found in nearly half of all sites sampled across a ward within 10 hours and persisted for at least five days. The study, by University College London and Great Ormond Street Hospital (GOSH), is published as a letter in the Journal of Hospital Infection.
Researchers placed the water containing the DNA on the hand rail in an isolation room – that is, a room for higher-risk or infected patients – and then sampled 44 sites across a hospital ward over the following five days. They found that after 10 hours, the surrogate genetic material had spread to 41% of sites sampled across the hospital ward, from bed rails to door handles to arm rests in a waiting room to children’s toys and books in a play area. This increased to 59% of sites after three days, falling to 41% on the fifth day.
The highest proportion of sites that tested positive for the surrogate came from the immediate bedspace area – including a nearby room with several other beds – and clinical areas such as treatment rooms. On day three, 86% of sampled sites in clinical areas tested positive, while on day four, 60% of sampled sites in the immediate bedspace area tested positive.
SARS-CoV-2 will likely be spread within bodily fluid such as cough droplets, whereas the study used virus DNA in water. More sticky fluid such as mucus would likely spread more easily.
One caveat to the study is that, while it shows how quickly a virus can spread if left on a surface, it cannot determine how likely it is that a person would be infected.
Dr Lena Ciric of UCL, a senior author of the study, said in a statement: “Our study shows the important role that surfaces play in the transmission of a virus and how critical it is to adhere to good hand hygiene and cleaning. Our surrogate was inoculated once to a single site, and was spread through the touching of surfaces by staff, patients and visitors. A person with SARS-CoV-2, though, will shed the virus on more than one site, through coughing, sneezing and touching surfaces.”
Source: University College London
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