An early study by University of Nebraska Medical Center researchers and others has found some potential for airborne transmission of the novel coronavirus.
But it’s not the type of spread associated with highly contagious airborne diseases such as the measles and chickenpox.
The researchers stressed, however, that their findings do not confirm that the virus spreads in an airborne fashion. While they recovered the virus’s genetic material in the samples they collected, more study is underway to determine whether they captured live virus that can be grown in the lab. Additional evidence also is needed to determine the risk of airborne transmission of the virus.
“It doesn’t appear to spread like classic airborne viruses,” said Dr. Mark Rupp, chief of UNMC’s infectious diseases division. “We’re not seeing that with COVID-19.”
Many things, in fact, still aren’t known about the virus and how it spreads, including how much it takes to infect another person. The report, published in an online archive before peer review by outside scientists, is one of many that researchers around the world are conducting and publishing rapidly as they seek to get a better handle on the virus.
In this case, the researchers collected samples from the air, in bathrooms and from surfaces in 11 isolation rooms that housed some of the original 13 people who tested positive for COVID-19, the illness caused by the virus, after being rescued from a stricken cruise ship.
The 13 were among a total of 15 passengers who were monitored and treated in the Nebraska Biocontainment Unit and the National Quarantine Unit, both on the UNMC campus, between mid-February and mid-March. The researchers are affiliated with UNMC, Nebraska Medicine and the University of Nebraska’s National Strategic Research Institute.
The study found high levels of contamination by the virus, detected by genetic testing, on commonly used surfaces and in the air of patients’ rooms. Air samples from hallways outside of rooms where staff were moving in and out of doors also were positive.
The study suggests that COVID-19 patients, even those who are only mildly ill, may create aerosols of virus and contaminate surfaces that may pose a risk of transmission.
The findings, the researchers wrote, suggest that the virus might be spread through both larger droplets produced when people cough or sneeze and person-to-person contact, as well as through indirect contact with contaminated objects and airborne transmission.
Rupp said the study doesn’t do much to change recommendations for the general public. The federal Centers for Disease Control and Prevention has posted guidance on how to prevent spread through close contact with family members, including limiting an infected person to a separate bathroom and bedroom if possible.
That guidance includes information on properly cleaning surroundings if someone has a respiratory illness. The virus is believed to be killed relatively easily by a long list of household cleaners.
It does, however, emphasize the need for aggressive social distancing. “This will really crimp down the transmission of this virus from person to person in society,” Rupp said in a discussion of the study on Facebook Live.
Rupp said he did not believe the general public needed to wear masks.
Tuesday, Dr. Jeffrey Gold, UNMC's chancellor, posted a video on YouTube about airborne transmission.
Whether to recommend that the public wear cloth masks when out and about is a matter the CDC reportedly is reviewing. Any recommendation, however, is expected to come with the caveat that medical masks be reserved for health care providers.
The study also shows how important it is for health care workers caring for COVID-19 patients to take precautions against virus transmission, said John Lowe, UNMC’s vice chancellor for Inter-professional Health Security Training and Education.
“That means wearing the proper personal protective equipment, using negative air pressure rooms for these patients whenever possible and being mindful about the method of entering and exiting these rooms,” he said.
Dr. James Lawler, director of the Global Center for Health Security at UNMC, said teams who were caring for the cruise ship passengers were taking such precautions and will continue to do so, even as the number of patients increases.
More research, however, is needed to characterize the virus’s environmental risk.