Speaking to the BBC on Sunday, Barclay said: ""It is the first time that the World Health Organization has acknowledged that the airborne route contributes to the spread of this disease.
"Of course, there are other routes as well... But what this new acknowledgement means is that the route through the air probably also contributes in some circumstances."
Barclay said the virus could remain suspended in the air and travel some distance away from the person who had breathed them out, with laboratory studies showing it could remain infectious in the air for more than an hour.
She added that replenishing the air in a room was important to avoiding spreading the virus, rather than recirculating the air like some air conditioning systems do.
Barclay's remarks come after the World Health Organization (WHO) last week acknowledged that there emerging evidence that COVID-19 can be spread by tiny particles suspended in the air, the BBC reported.
The airborne transmission could not be ruled out in crowded, closed or poorly ventilated settings, a WHO official had said.
WHO officials have cautioned the evidence is preliminary and requires further assessment.
If the evidence is confirmed, it may affect guidelines for indoor spaces.
As of Sunday, the total number of global coronavirus cases stood at 12,735,924, with 565,489 deaths, according to the Johns Hopkins University.