SYDNEY – An Australian biosecurity laboratory has started the first comprehensive global animal trials of potential Covid-19 coronavirus vaccines and said it expects human testing to begin in several months if they are successful.
The two candidate vaccines were developed by researchers at University of Oxford in the United Kingdom and American company Inovio Pharmaceuticals as part of an international collaboration that is now funding eight partners.
Scientists said ferrets were deliberately injected with the candidates at the Australian Animal Health Laboratory, a facility in Victoria run by the Commonwealth Scientific and Industrial Research Organization (CSIRO).
“Eventually we will challenge the ferrets — we’ll inoculate them with some of the virus and see how they compare to unvaccinated controls,” said director Professor Trevor Drew.
The ferrets, used in the tests because they have a similar virus reaction to humans, were fine afterward apart from fevers, he said.
A third candidate vaccine developed by the University of Queensland has also started initial animal trials. Full tests are likely to begin within weeks.
The vaccines are being funded by the Coalition of Epidemic Preparedness Innovation (CEPI) and the World Health Organization (WHO), which will choose the best two candidates for human tests and then commercial production.
Other partners in the program are US biotechnology companies Moderna and Novavax, German pharmaceutical group CureVac, University of Hong Kong and a consortium comprising France-based Institut Pasteur, Austrian biotechnology company Themis and the University of Pittsburgh in the US.
Scientists at the CSIRO will check whether the candidates work and if they would be safe for human testing, with initial results expected to be ready as soon as early June. Clinical trials will be approved if they are successful.
CSIRO director of health and biosecurity Rob Grenfell said the trials were being fast-tracked at an unprecedented pace, but cautioned that it would still take many months for the vaccines to meet regulatory requirements.
“Normally it takes about one to two years to get to this point and we’ve in fact shortened that to a period of a couple of months,” Grenfell said. “The end of the year would be an optimist’s view [for an approved vaccine]. Early next year would be closer to the reality, all things working well.”
The University of Oxford’s candidate is a vector vaccine that uses a “defective” virus to introduce Covid-19 proteins to the immune system and induce a response. The virus itself does not harm the patient, as it cannot replicate.
The Inovio candidate is designed to encode certain Covid-19 proteins to the immune system, which should then prompt the body’s cells to generate the same proteins before the immune system reacts to them.
University of Queensland’s candidate vaccine has undergone initial animal studies in Brisbane. A full pre-clinical program, including tests on animals, will get underway at the CSIRO’s Victorian facility within weeks.
Paul Young, head of the School of Chemistry and Molecular Biosciences, said his researchers tested 100 different versions of a protein before choosing the one that showed most promise against the coronavirus.
He said the trials would test whether the candidate induces the immune response the team is expecting. If so, human trials could begin by June.
“What we are aiming for is [a vaccine in] somewhere between 12 and 18 months, which is remarkably quick,” Young added.
The Pittsburgh consortium has already conducted initial tests of a vaccine candidate on mice and discovered that it can induce an immune response against the Covid-19 coronavirus at levels that might prevent infection.
They used a patch design known as a micro-needle array, consisting of 400 tiny needles made out of sugar and a spike protein, to give the vaccine more potency. This targets the skin, where the immune reaction is strongest.
Researchers said it was too early to determine whether there would be a lasting immune response against the virus, nor how long it was effective. The consortium hopes to begin human clinical trials within the next few months.
Hong Kong University, which joined the CEPI partnership two weeks ago, was given initial funding of US$620,000 to undertake preclinical testing of a candidate vaccine. Its prototype uses a weakened version of the flu virus that was adapted to express the surface protein of the Covid-19 coronavirus.
The same approach was used to develop preclinical vaccine candidates against Middle East Respiratory Syndrome, another novel coronavirus.
No timetable has been announced for the start of preclinical testing.
Meanwhile, the National University of Singapore and US pharmaceutical firm Arcturus Therapeutics expect to start clinical trials of a candidate later this year that uses a non-viral delivery system to produce proteins.
Their clinical method, which uses nanoparticle technologies, is designed to produce a response at much lower doses compared with traditional vaccines, which enables more people to be treated with a single batch.
“By using a molecular approach to measuring these outcomes, rather than waiting and seeing whether these happen clinically, we shorten the process from what would otherwise take six months down to a few days,” said Ooi Eng Eong, NUS’ deputy director of emerging infectious diseases.