The killer coronavirus can spread through the air and remain contagious for hours, another study has suggested.
US scientists found high levels of the bug lurking in the air in rooms long after patients had left.
What's more is that traces of the coronavirus were also discovered in hospital corridors outside patients' rooms, where staff had been coming in and out.
The University of Nebraska researchers behind the study say the finding highlights the importance of protective clothing for healthcare workers, reports Daily Mail, UK.
It follows a wealth of studies that have suggested the highly contagious disease does not just spread via droplets in a cough or sneeze.
Scientists around the world are scrambling to understand how the virus, which has now infected 785,282 people and killed almost 38,000, sheds and spreads.
The latest study, which has not been peer-reviewed by other scientists yet or published in a scientific journal, took samples from 11 patients' rooms after they had been placed in isolation following a diagnosis.
The researchers found viral particles in the air both inside the rooms and in the hallways outside of the rooms.
Their finding suggests people may be able to contract the bug without ever being in direct close proximity to an infected person.
The study's authors said this highlights the importance of wearing personal protective equipment (PPE).
Shortages in the UK have meant NHS workers cannot get their hands on PPE, with some staff resorting to buying their own from DIY stores.
Lead author James Lawler, an infectious diseases expert at the Nebraska University, said in a statement: 'Our team was already taking airborne precautions with the initial patients we cared for.
'This report reinforces our suspicions. It's why we have maintained COVID patients in rooms equipped with negative airflow and will continue to make efforts to do so - even with an increase in the number of patients.
'Our health care workers providing care will be equipped with the appropriate level of personal protective equipment. Obviously, more research is required to be able to characterize environmental risk.'
The researchers also found traces of the bug on commonly used items such as toilets, adding to the theory that the virus can spread on surfaces.
Fears the virus can survive on surfaces have existed since the outbreak began in Wuhan, China, last December.
England's chief medical officer has warned people can get infected by touching any contaminated surfaces and then touching their face.
Professor Chris Whitty said the coronavirus can stay contagious on hard metal or plastic surfaces like door handles or handrails for as long as three days.
It comes after the Royal College of Nursing (RCN) yesterday revealed there are medical staff working to save lives and turn the tide in Britain's war with coronavirus that have no access to basic protective clothing at all.
Dame Donna Kinnair, chief executive and general secretary of the RCN, has blasted the 'unacceptable' levels of masks, gloves and aprons in some hospitals and care homes.
Whistleblowers in the NHS say they have been 'hiding' safety equipment for their next shifts and others have gone off sick fearing they will fall ill if they don't get away from work.
Dame Donna's warning based on worried emails and phone calls from nurses came as horrifying pictures of unprotected staff on the frontline emerged today despite new Government guidance making it clear that anyone within 3ft of coronavirus victims must wear full PPE.
She said: 'I am hearing from nurses who are treating patients in Covid-19 wards without any protection at all. This cannot continue. They are putting themselves, their families and their patients at risk.
'Every minute we wait is a minute too long. All nursing staff, no matter where they work, must feel safe. We need action, we need equipment, we need it now'.
She added: 'The Government is finally prioritising Covid-19 testing for NHS staff, including social care, but it is completely unacceptable that weeks into this crisis there are colleagues in all settings - hospitals, community or care homes - who have not been provided with personal protective equipment.
'As the professional trade union representing potentially the largest group of affected workers, the RCN has said repeatedly that we will not accept anything less than aprons, gloves and masks for all staff, in all settings. But this is a minimum - and that is why we are so disappointed even that level of protection has yet to be provided'.
NHS medics must wear full protective equipment if they come within three feet of a coronavirus patient, the government warned today, as shortages of the gear saw a brave nurse forced to dress in just an apron and gloves.
But numerous medical staff including doctors and nurses have expressed serious concerns about a lack of PPE in NHS hospitals.
One described how staff are 'hiding' equipment out of sheer desperation.
Some workers are saying they are sick as they fear the provisions are inadequate, another said.
Another doctor compared the situation to sending a soldier to war without the necessary equipment while a junior doctor said it feels like it is 'inevitable' that they will contract the virus due to a lack of PPE
Public Health England has issued stricter guidance on personal protective equipment (PPE), making it a requirement to wear a face mask, gloves, an apron and eye-protection as a shield against infectious airborne droplets.
A global shortage of the equipment medics and carers need to protect themselves against Covid-19 have led to shortfalls in the UK, with warnings the lives of thousands of NHS staff are being put at risk.