covid-19
(Image: AAP/James Gourley)

There are more than 3000 coronavirus cases in Australia still under investigation, with many of Victoria’s cases coming from unknown sources.

Without knowing the source of the virus, little can be done to halt the source of the cluster. Crikey takes a look at some common myths and theories around where people are picking up COVID-19 infections.

✓ Close contact Chair in Epidemiology at Deakin University Professor Catherine Bennett told Crikey the most likely unknown source was through close contact of an infected person. 

“Victoria has wide enough spread that it doesn’t take much to lose connections between asymptomatic carriers, non-identified cases and those with mild illnesses who don’t get tested,” Bennett said.

“You get other cases that appear to be random, but are actually connected through these invisible chains.” 

Close contacts in Victoria are defined as people who have been sitting across from an infected person for 15 minutes, or in the same room for two hours.

“You might be getting it from the air — either through droplets or aerosols,” Bennett said.  

New research has suggested COVID-19 is not just transmitted through dense droplets, but through smaller, lighter air particles which float in the air for longer.

✖ Surfaces Deep cleaning of offices, wiping down gym equipment and pre-packaged goods in supermarkets: surface transmission has been talked about as a risk for a while, but how common is it to catch COVID-19 from a table? 

According to Melbourne University biostatistics expert Dr Alex Polyakov, pretty unlikely. 

“It could happen if an infected person touches a surface, then another person immediately touches the surface, then immediately touches their face,” Polyakov told Crikey.

“We don’t think the virus survives that long on surfaces.”

COVID-19 could survive anywhere from minutes to hours to days depending on the surface, temperature and humidity of the environment, though one study found these results had little resemblance to real-life scenarios. 

✓ Through the eyes Horrifyingly, research has suggested droplets or air particles with COVID-19 can enter the body not just through the mouth and nose, but through the eyes, too. 

“Say you get into a lift shortly after someone has sneezed, the virus may be present in very very small droplets of saliva that float around in the air. If that gets into your eyes, that’s a possible route of transmission,” Polyakov said. 

“That’s why a lot of major hospitals now recommend not just masks, but face shields, too.”

✖ Young Children Children as a possible petri dish of transmission is often raised when debating whether schools should reopen.

Garvan Institute of Medical Research immunologist Dr Stuart Tangye told Crikey children aged 10 to 19 spread the virus at least as well as adults do.

“As for kids under 10, that’s ambiguous,” he said.

One study in Iceland suggested kids under 10 were less likely to catch the virus — though for those who do catch it, it can be dangerous with some developing features of toxic shock syndrome and atypical Kawasaki disease. 

✖ Pets Dogs, cats and tigers have caught COVID-19 from humans. So how likely is it that our beloved four-legged friends are passing the virus along?

Not very. Cases are far and few between, though little research has been done, Tangye said. 

“Experimental animals like mice and rats don’t get infected with SARS-COV 2 … it’s possible the virus could mutate to use other domesticated animals as their host,” he said.

The virus has not been reported in pets, livestock or wildlife in Australia.

✓ Masks Dean of the School of Health Sciences at Swinburne University Professor Bruce Thompson told Crikey misuse of personal protective equipment, including face masks, is a potential source of infection. 

“As soon as you put your mask on, you need to make the assumption that it has COVID-19 on it,” he said, adding it’s more likely a person will reinfect themselves with COVID-19 than catching it from another person’s saliva droplets landing on the mask. 

“Your mask is like your underwear: don’t take them off or touch them in public,” he said. 

Importantly, Thompson added, the main reason the virus is spreading is because humans are giving it to humans. 

“We need to focus on the majority of transmission cases … it’s not from pets, the footpath or a loaf of bread, it’s mostly from humans to humans.”