Two biggest risk factors when queuing

QUEUES at shops or cafes as COVID-19 restrictions ease will be high-danger zones for virus transmission if they do not move quickly and people are not adequately spaced, one of the country's leading infectious disease expert warns.

University of Queensland graduate and now head of clinical research at the National Centre for Immunisation Research and Surveillance Professor Robert Booy told The Courier-Mail the 1.5m regulation was an absolute minimum, and Queenslanders should look to spread out further.

He also highlights that hanging around in a queue for 15 minutes or more heightened the risk of infection.

This comes as a global transmission researcher warns that droplets from coughs and sneezes could propel as far as 8m.

"There is the worry of a new wave of coronavirus, and people must understand that distance and time is vital in keeping them safe when isolation eases," Prof Booy said.

"In queues Queenslanders should look to be 2m apart, and if they stand around for 15 minutes or more the risks blow out.

"It is necessary that queues move fast.

"If someone is 2m away from a COVID-19-positive person rather than 1m away they are reducing their risk tenfold."

Queensland stores have already introduced snaking queuing systems so it is vital to be distanced from the person in front as well as those in the next lane.



Meanwhile, a global disease transmission expert says the 1.5m guidelines are 90 years old and has called into question their value in modern society.

Associate Professor Lydia Bourouiba, from the Fluid Dynamics of Disease Transmission Laboratory at the Massachusetts Institute of Technology - a private research university - says the distancing measures were modelled in the 1930s.

"Although such social distancing strategies are critical in the current time of pandemic, it may seem surprising that the current understanding of the routes of host-to-host transmission in respiratory infectious diseases are predicated on a model of disease transmission developed in the 1930s that, by modern standards, seems overly simplified," she writes in a commentary in the Journal of the American Medical Association.

The fears of the transmission researcher have been shared in Australian Doctor magazine.

Prof Bourouiba said exhalation, sneezes and coughs were primarily made of a multiphase turbulent gas (a puff) cloud that entrained ambient air and trapped and carried within it clusters of droplets with a continuum of droplet sizes.

This turbulent gas cloud could propel respiratory droplets up to 7-8m.

The professor said a report from China that studied COVID-19 patients was consistent with the gas cloud hypothesis.






Originally published as Two biggest risk factors when queuing