Pre-clinical trials will assess how effective and safe the potential vaccines are using an animal model before human testing. Mirjam Guesgen reports.

The Australian national science agency, CSIRO, has begun testing two potential vaccines for Covid-19, with results due by June, 2020.

These pre-clinical trials will assess how effective and safe the potential vaccines are using an animal model and are the first step before human trials.

Other laboratories worldwide have already begun human testing, but the Director of Health and Biosecurity at Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO), Rob Grenfell, said their pre-clinical trials are vital to “ensuring no vaccine reaches the market that causes more harm than good”. Speaking this morning, he said they’re working as fast as they can (most vaccines take years to develop) without compromising safety.

There are currently dozens of vaccine hopefuls out there, but the two CSIRO are testing were recommended by the World Health Organisation and the Coalition for Epidemic Preparedness Innovations.

Vaccinologist Helen Petousis-Harris said any vaccine remains around 12 to 18 months away. “If we flatten the curve we can potentially buy time until we get vaccines,” the University of Auckland associate professor said.

“Effective treatments will probably come first which will alleviate some of the death toll and serious cases. Vaccines will likely follow. Deployment of vaccines will ultimately stop Covid if it does not burn out before this.”

CSIRO will test the vaccines in ferrets, because their lungs are similar biologically to humans and the virus duplicates itself in a similar way to humans.

Although this is an early-stage trial, scientists are being realistic yet optimistic. “I cannot recall an example of where the world science teams have actually worked together in such harmony to solve such a perplexing problem. That in itself gives us a lot of hope,” said Grenfell. “We know that the journey from here has a lot of technical pitfalls and a lot challenges along the way.”

As with all vaccines, these examples will try to trigger a person’s immune system by presenting it an inactive form of the virus or certain virus proteins. Once the immune system has been triggered, it will be primed to fight infection should a person get the virus later on.

One vaccine, developed at Oxford University in the UK, is what’s known as a vector vaccine – it carries a replica part of the SARS-CoV-2 virus, which can’t cause disease. The second vaccine, developed by US pharmaceutical company Inovio, sends in a gene that codes for part of the virus. Our cells then make a protein from those DNA instructions – essentially our bodies make the vaccine for us.

Ferrets will be given each vaccine, either using a nasal spray or as an injection into the muscle, and will then be infected with Covid-19 sometime later to see how their bodies respond. Scientists will compare the responses of vaccinated ferrets with unvaccinated ones. If the vaccines are effective, the virus shouldn’t show up in the animals’ poo.

Scientists are also keen to keep an eye on any side effects of the vaccine. Because of the way the immune system works – by telling infected cells to kill themselves – there is a risk that the vaccines could cause damage to lung tissue. This was the case for a SARS vaccine back in 2012.

The intricacies of whether the vaccine will be effective for everyone will become clearer once human trials begin, said Professor Trevor Drew, the director of CSIRO’s Australian Animal Health Laboratory.

For now, Grenfell is urging people to continue acting safely to slow the spread of the virus. That means staying at home, keeping in our bubbles and washing our hands. “If we can keep the rate of new infections every day below certain levels then those individuals that get severe disease and are hospitalised receive the care they need,” he said.