A study has suggested that traces of coronavirus can linger in the air – with researchers finding material in hospital toilets and rooms where medical staff change out of protective gear.
In February and March, researchers analysed hospitals in Wuhan, China, with sensitive detectors that detected the virus’ genetic material.
They found that traces of its genetic material were detectable in rooms including an indoor space with large crowds. The study is published in the journal Nature.
But other experts have pointed out that the tests used are very sensitive, and can pick up “dead or degraded” virus, not just infectious virus.
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Whether this means that the virus can be transmitted through the air is open to question, scientists have said.
Until now, the novel coronavirus has been shown to be transmitted via close contact with infected people, contact with a contaminated surface, and inhalation of respiratory droplets.
Analysis by the World Health Organization (WHO) of 750,000 cases in China found no evidence of airborne transmission.
The new study does not prove that the virus can be transmitted through the air, merely that traces of the virus can travel through the air, said Professor Lawrence Young, a specialist in molecular oncology at the University of Warwick.
Young said: “This publication shows that the genetic material (RNA) of SARS-CoV-2 can be detected in aerosols sampled from various locations in two hospitals in Wuhan.
“It highlights the capacity for protective materials worn by medical staff to contaminate areas where this protective clothing is removed and for ventilation to disperse the virus RNA.
“The study also demonstrates that outside areas where people congregate could also be a source of the virus.”
But the study does not prove that live viruses are travelling through the air, Young added.
He said: “Detecting the virus genetic material (RNA) with a very sensitive test (RT-PCR) is not the same as detecting infectious virus. Dead or degraded virus would still be detected with this technique.
“In fact, this method is so sensitive that there needs to be stringent control measures to prevent sample cross-contamination. The sampling of aerosols is subject to enormous variation and the small sample size in this study also means that the data needs to be interpreted with caution.”
The study instead demonstrates the importance of existing measures to contain the virus, such as washing hands after touching surfaces.
Young said: “This study supports previous work which shows that infectious virus can be shed into the environment and remain viable (infectious) on surfaces for up to three days.”