All results to date show the Australian coronavirus vaccine candidate is safe and "likely to provide protection" against Covid-19, researchers say.
Photo: AFP
Scientists from the University of Queensland (UQ) released information about the vaccine's pre-clinical trials, showing it triggered the immune system to protect against the disease.
During the trial, the UQ team gave doses of their vaccine to hamsters and then exposed them to Covid-19 to test whether the drug provoked the desired immune response.
Keith Chappell from the UQ School of Chemistry said this was just "one step in the process".
"Following a single dose, we see a really good level of protection against virus in the lung," he said.
"Around half of the animals had no virus at all detected in the lungs and the other half had reduced levels.
"We saw a marked reduction in the severity of the disease in the hamsters."
Chappell said the vaccine was likely to provide protection against both the virus and symptoms of the disease, according to the pre-clinical trial data.
"The protection we saw after a single dose was better than we expected," he said.
"[It] looks like two doses do a great job of protecting both against virus replication and the disease."
His colleague Trevor Munro said the double dose was in line with expectations of an effective vaccine.
"Everything we have seen so far gives us continued confidence to keep pushing," he said.
These tests were done on hamsters, but the UQ vaccine is already in phase one human trials.
Chappell said the trial was going well and there were "absolutely no safety concerns with all the participants dosed so far".
The trial has recruited 120 people, with the last 20 people given a dose this week.
Of the vaccine candidates currently in stage one clinical trials, the researchers said this was the first to release detailed results of hamster modelling.
The UQ scientists presented this crucial new data to the International Society of Vaccines overnight, sharing their findings with a group of scientists.
For the first time, scientists around the world will be able to compare the effectiveness of different vaccines.
"Until now, it has been extremely difficult to compare, but we are the first ones to make public how the vaccine is performing," Chappell said.
Currently there are more than 150 Covid-19 vaccines being developed, with several such as the Oxford University candidate already used in large-scale human trials.
Scientists are confident the Australian-developed candidate will be able to be mass-produced.
"With the optimisation that we've done and the proof of concept … this vaccine will be able to be produced at scale," Munro said.
They said as many as 10 million doses of the vaccine would be able to be produced at one time.
"The headline findings are that we can manufacture this vaccine in sufficient quantities to reach a large percentage of the population," Chappell said.
Researchers said it was too early to say whether people would need an annual vaccine to maintain protection against Covid-19.
"That data would take time to come in," Munro said.
They found some virus continued to live in the respiratory tract, but was largely wiped out from the lungs of the animals.
"We are confident we are inducing the right type of antibody and t-cell response to best protect against the virus," Chappell said.
'They are thinking about the next step'
Magdalena Plebanski, a professor of Immunology at RMIT University, said the development was exciting and showed the UQ team was a potential contender in the race to find an effective and safe vaccine.
"But it's early days and we still don't know whether it will induce an immune response in humans," she said.
What impressed her about the UQ study was that the team were looking to accelerate the process of getting a viable vaccine into the community.
"They are thinking about the next step, about scale-up and production and they have shown scale-up is possible," Plebanski said.
She also said demonstrating hamsters could be used as animal models was an exciting new development.
Plebanski said the researchers had shown the pathology in the hamster lungs was similar to that in human patients, and the animals could be used to test new interventions and vaccines.
"It looks promising. Thus far, all the signs are good," she said.
"As to which is going to offer the best protection, it's still too early to know."
- ABC