UNC Chapel Hill professors back new theory of COVID-19 spread

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RALEIGH, N.C. (WNCN)- More than 200 scientists including three from UNC Chapel Hill, have asked the World Health Organization to consider a new theory for how COVID-19 may be spreading.

It’s widely believed the virus spreads through droplets traveling up to six feet before falling to the ground. The new theory suggests smaller virus-carrying particles are expelled from a person when speaking or even singing. Those particles then spread farther than six feet and stay suspended in the air for longer periods of time.

“I think it’s worth being worried about,” said Professory Barbara Turpin, department chair at UNC Chapel Hill’s Gillings School of Public Health. The professor explained people emit more of these particles than droplets.

Titled, “It is Time to Address Airborne Transmission of COVID-19”, an open letter to the WHO advocated new preventative measures to mitigate exposures through airborne transmission.

“Aerosal particles are coming out and forming a little cloud in front of my mouth- and then they really quickly spread with the rest of the air in the room,” said Turpin.

Turpin and the letter said there is a line of evidence supporting the plausibility of aerosol spread and that it needs to be taken seriously.

The professor explained theory has a bigger impact indoors. When spending time outdoors, aerosol particles are able to more quickly diluted and moved out of your immediate space. Indoors, those particles are able to move around with nowhere to go for extended periods of time.

Turpin gave an example of running on a greenway. She explained under this theory, passing by someone on the trail will leave you less likely to become infected than if you were running behind someone breathing heavily on a trail.

COVID-19 research is ongoing

Turpin said what is still unclear about COVID-19 is how much of the virus needs to move into a person’s system for them to be infected. It means whether you are exposed to COVID-19 via droplets or airborne particles, your chances of actually catching COVID-19 depends on how much you are exposed. She explained that might differ from person to person.

In a press conference this week, Prof. Benedetta Allegrazzi, WHO coordinator of the infection prevention and control unit said about the letter, ”These are fields of research that are really growing and for which there is some evidence emerging but is not definitive. And therefore, the possibility of airborne transmission in in public settings, especially in very specific conditions, crowded, closed, poorly ventilated settings that have been described cannot be ruled out.”

Dr Maria Van Kerkhove, WHO COVID-19 technical committee head said, “We welcome the interaction from scientists all over the world, from many different disciplines, many of the signatories are engineers, which is a wonderful area of expertise, which which adds to growing knowledge about the importance of ventilation, which we feel also is very important. We have been talking about the possibility of airborne transmission and aerosol transmission as one of the modes of transmission of COVID-19 as well as droplet.

Does the mode of spread matter?

Turpin said in some ways the mode of COVID-19 doesn’t matter. She said keeping your distance from people, limiting your contact with those outside your home and wearing a mask outside your home are important steps to avoid picking up the virus.

However, it does matter when it comes to limiting exposure. Turpin explained good ventilation can help clear the virus particles from a building or home. If ventilation is poor, those particles can more easily move across a room.

Turpin said the theory should make schools and places of business consider not only how many people are in a building and how far apart they are but how long they are in the building. She said the longer they are in the same building, the higher their chance of becoming exposed if someone in the building is infected.

“We are concerned that the lack of recognition of the risk of airborne transmission of COVID-19 and the lack of clear recommendations on the control measures against the airborne virus will have significant consequences: people may think that they are fully protected by adhering to the current recommendations, but in fact, additional airborne interventions are needed for further reduction of infection risk”

It is Time to Address Airborne Transmission of COVID-19

Professor Glenn Morrison and Professor Jason D. Surratt, both with the department of Environmental Sciences and Engineering were also signatories on the letter to the WHO.

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