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The coronavirus can be found lingering in the air even when patients are not in the room, according to a new study.

Scientists found traces of the virus in rooms and outside hallways at the University of Nebraska Medical Center, where patients who were diagnosed were put into isolation, according to the report on MedRxiv.

“We also did identify a number of samples that detected the virus genes in the air, which confirmed for us the value in prioritizing respiratory protection when possible and prioritizing negative-pressure environments to provide direct patient care to these individuals,” said co-author John Lowe, who is vice chancellor for Interprofessional Health Security Training and Education, in a statement.

The study, which has not been peer-reviewed, collected air samples from 11 hospital rooms and found high levels of concentration of the virus.

Samples from hallways outside of rooms where hospital employees had come in and out of the doors were also positive, the report said.

Researchers said the study doesn’t evaluate whether the virus is contagious in the air, but reinforces the need for personal protective equipment for medical staff until there are more conclusive findings on the subject.

“Studies like these are needed to understand proper precautions for health care workers, first responders and others who care for the ill and are needed to combat this pandemic,” said co-author Joshua Santarpia, who is an associate professor of pathology and microbiology at the University of Nebraska Medical Center.

“This ongoing work will continue to improve our understanding of… transmission and help identify ways to improve safety in the care of patients with this disease.”

The World Health Organization has insisted that the virus is primarily transmitted through respiratory droplets, such as coughs and sneezes.