Coronavirus DNA could spread across hospital ward within ten hours

Viral DNA that models the coronavirus was present on nearly half of all ward sample sites after just ten hours in a simulation study.

Following placement of a sample of viral DNA on a bed rail, 48 percent of locations sampled across a hospital ward had viral DNA present after ten hours. The DNA persisted on surfaces throughout the ward for at least five days, and was found to have travelled a distance of 260 feet from the inoculation site. 

A letter to the editor of the Journal of Hospital Infection, titled 'Let’s not forget surfaces', contained results of the study showing how the virus could spread from a single site, in this case an isolation room bed. The joint Great Ormond Street Hospital (GOSH) and University College London (UCL) study did not name the hospital involved but made suggestions based on the results for cleaning regimes and hand hygiene, such as frequent cleaning and regular hand-washing, to prevent spread in clinical environments in general.

Researchers used a 'surrogate' virus that cannot infect humans, rather than SARS-CoV-2, the virus responsible for the current pandemic. This removed any risk of a propensity to cause the disease and allowed viral spread through water droplets to be simulated in a clinical setting. 

The viral DNA was added to water in similar concentrations to those found in infected patients' respiratory samples and 44 sites were then sampled across the ward for five days. The bed originally infected was located in an isolation room where higher risk patients are kept, so would be expected to have heightened cleaning and hygiene regimes compared to the rest of the ward.

The largest number of samples tested positive after three days, when 60 percent of the locations across the ward were found to have traces of viral DNA. Researchers varied the types of samples sites across the ward and the highest proportion of infected sites were in the immediate isolation room area and a nearby room with several other beds and clinical areas such as treatment rooms.

The team cautioned that their study explored the way the virus could spread across surfaces and does not indicate the likelihood that a person will become infected from contact with a contaminated surface.

Dr Lena Ciric, co-author from UCL, said: '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.'

Dr Ciric also related this to patient spreading of the virus: 'It 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.' The study also outlined how coronavirus could spread even more quickly due to droplets also containing mucus, which is more sticky than the water solution droplets used in this study.

Lead healthcare scientist at GOSH and co-author of the study Dr Elaine Cloutman-Green added that 'cleaning and hand-washing represent our first line of defence against the virus and this study is a significant reminder that healthcare workers and all visitors to a clinical setting can help stop its spread through strict hand hygiene, cleaning of surfaces, and proper use of personal protective equipment (PPE).'