In a media briefing on 02 April Director for CSIRO Health and Biosecurity Dr Rob Grenfell said that it’s a “very special time due to the global pandemic disaster,” and what usually takes the CSIRO a year to achieve has been done in just a few months.
“We have identified there are three distinct clusters globally and we’re looking at how this will impact the severity of the infection people get and that we’re developing the right structures for the vaccine that may work,” he said.
CSIRO are currently, as of 15 April 2020, in pre-clinical stage which means they are not testing on humans, they’re testing on ferrets.
Ferrets, according to CSIRO Director of AAHL (Australian Animal Health Laboratory) Professor Trevor Drew, were used as a model for the 2002-2003 SARS outbreak and are a “very good” model for influenza. The reason why CSIRO chose to test SARS-COV-2 in ferrets is due to the fact that the team is very used to working with the model and have prior knowledge to help them.
“Ferrets have a specific receptor called Ace2 which is seen on a number of animals,” which also includes humans. Through the work on the model CSIRO have discovered that SARS-COV-2 can replicate not only in the lungs but also in the intestines which is why it can be excreted.
Herd immunity, not such a great idea
In terms of herd immunity, it’s hard to fathom what that would mean for the Australian population. According to Professor Trevor Drew …”in some instances when a human responds to the disease, sometimes that immune reaction can cause damage to the lungs in particular but possibly also damage to other organs. So this is why we’re very careful and want to fully understand both the course of disease in the infected animal and also a vaccinated and then challenged animal,” he said.
“The basis of this immune response is that when cells of the immune system see an infected cell they tell it to kill itself. So this signal can cause overt damage to the lungs if there are a lot of cells in the lung which are infected at that time. Also other arms of the immune system that can also damage the tissues so we need to make sure that any vaccine that we trial, we need to measure its ability to produce a defence immune response which actually gets rid of the virus but without causing this overt damage to the tissues.”
To achieve herd immunity within our population can only happen through two avenues. The first option is to let everyone become sick, contract the virus and develop an immunity to it. The second option is to wait for a vaccine and then vaccinate as much of the population as possible.
The problem with option one is that according to Professor and Dr William Hanage in an article for The Guardian, “vulnerable people should not be exposed to COVID-19 right now in the service of a hypothetical future.”
Even though the mortality rate (rate of infected people that die from the virus) is low, even a low mortality rate of the entire Australian population is a large number. Due to the ongoing nature of the pandemic, it’s actually quite difficult to calculate what the mortality rate is. Initially reported by the WHO as 2%, in some countries that number is as high as 5-8% mortality rate.
2-8% of the Australian population dying to achieve herd immunity should not even be contemplated by the Australian government. More importantly, because the virus is Novel (new) we don’t even know if we can get herd immunity for the virus.
Australia is not “leading the way” in testing, despite what the Australian Government says
Only today 15 April have state governments across Australia expanded the testing criteria. Due to the 5-6 day incubation and the four-day long weekend expect to see a rise in the number of reported cases.
“From tomorrow, any South Australian who has a fever or respiratory symptoms consistent with COVID-19, no matter how mild, is encouraged to attend a COVID-19 clinic or their GP, for assessment and testing,” says SA Health.
“The testing blitz will last for two weeks and will give symptomatic South Australians the reassurance they are not infected, while also providing public health clinicians greater understanding of the prevalence of the virus within the state.”
South Australia has a number of COVID-19 clusters in areas such as the Adelaide Airport and the Barossa Valley Region. The clusters caused 750 Qantas staff forced to self-isolate and travel in and out of the Barossa Valley Region to be discouraged.