Fine microdroplets, too small for the human eye to see, may have the ability to spread COVID-19 when someone is shouting, singing, speaking loudly or even, in some cases, by just breathing, warned Professor Jon Watson.

“Six months into the pandemic, we are still now discovering more about the virus and there is increasing evidence that COVID-19 is spread by microdroplets, though more work is still to be done in this area.

If you are socially distancing outside, then the chances of the microdroplets travelling far enough to infect someone else are low.

Professor Jon Watson

 “Initially, when the virus was first discovered earlier this year, we thought it was spread solely by droplet transmission which is essentially when someone coughs or sneezes and a visible droplet spreads the virus. Now there is evidence of spread by microdroplet.

“If you are socially distancing outside, then the chances of the microdroplets travelling far enough to infect someone else are low. However, if you are in an enclosed space and the ventilation in that enclosed space is not as good as it should be, then that increases the risk. 

“So now quite a few health centres, supermarkets and shopping centres are mandating masks for their staff, particularly if they are in front-facing positions. I think that is sensible, if we think this virus can be transmitted by these microdroplets then having a Perspex screen alone is probably not going to protect us. 

“It is also important to remember that microdroplet transmission can occur if the person carrying the virus then touches their face, their mask, their lips or blows their nose then does not observe good hygiene and does not sanitise their hands and then touches a surface that someone else goes on to touch afterwards. The virus can probably live for an hour or two on that surface and can be picked up again.”

Following the recent winding back of restrictions in WA that has seen big crowds gather at football games and music concerts and possibly shouting and singing, Professor Watson said he was not concerned at this stage due to the low level of viral transmission in WA, but that it should be reassessed if the infection rate increased.

Further guidance is expected to come from a German research study that will use DNA technology to track the microdroplet spread in a crowd of 4000 masked research participants attending a music concert.