Understanding COVID-19

Associate Professor Allison Imrie is a virologist in the Faculty of Health and Medical Sciences’ School of Biomedical Science, with knowledge of the history of novel viruses and their transmission. She has shared responses to some commonly asked questions surrounding COVID-19 in a dedicated factsheet produced by UWA. 

Professor Imrie explained that novel viruses are those we did not know about until they were identified. This can happen by investigating an outbreak of a new disease, by looking for novel viruses, or even accidentally while investigating something different.

A key question during this COVID-19 environment has been around transmission and what makes a virus easy to pass on. Professor Imrie said it was because the virus itself was able to infect human cells and tissues that, in turn, allowed for more efficient transmission.

A virus that infects the respiratory tract is more transmissible between people than a virus that infects nerves. Also, some human hosts may be more infectious than others. ‘Superspreaders’ are people who have been reported to infect many more people than they might otherwise be expected to.

Professor Imrie

The COVID-19 virus, or SARS-CoV-2, was first identified in December 2019 in people who presented with pneumonia of unknown cause. A novel coronavirus was then identified in all patients, most of whom had visited a seafood market in Wuhan, China. It is possible, Professor Imrie said, that the virus had been circulating elsewhere in China before December 2019, but had not been identified.

Within two months of the beginning of the outbreak in February 2020, more than 80,000 cases with more than 2800 deaths had been reported, mostly in China. Professor Imrie said each infected person could infect 2.2 other people. While this is deemed efficient transmission, it means other viruses are more infectious, such as measles, chicken pox and mumps.

 So, how exactly did the virus spread so quickly? It comes down to our behaviour.

“People travel more now than ever before in human history, and they arrive at their destinations very quickly,” Professor Imrie said.

“This means a person can be infected in one country or area and take their infection with them to their new destination, and infect others.

“When you combine this pattern with a highly infectious respiratory virus that is transmitted by droplets and perhaps aerosols, you have the situation we see now with COVID-19.”

Looking ahead, Professor Imrie said we still don't know if the antibodies produced against the virus will protect us from a second infection. still waiting for confirmation that if you recover from COVID-19, you are immune from the virus.

"We also don’t know how long our immune memory of the infection lasts," she added.

For answers to these questions on COVID-19, download our dedicated factsheet.

• What is a novel virus and how often does one occur?

• How does a virus jump from animals to humans?

• Are there certain at-risk animals in which this is more likely to occur?

• What behaviours around the globe and locally in WA increase the risk of a virus jumping from animals to humans?

• What is it about a virus that makes it easy to pass on?

• How did recent pandemic viruses emerge?

• How easy is the COVID-19 virus (SARS-CoV-2) to pass on in comparison to other viruses?

• How exactly does it enter via the nose and mouth, and where does it go from there?

• How does a virus spread so quickly, from a single market to across the globe, in a few short months?

• Has the COVID-19 virus spread been quicker in comparison to other pandemics?

• If you recover from COVID-19, are you then immune from the virus and can’t be infected again?