COVID-19 vaccine commences human trials in Adelaide

The SARS-Cov-2 vaccine candidate known as COVAX-19 has become the first COVID-19 vaccine developed in the Southern Hemisphere to commence human trials, according to its creators, with a Phase 1 trial kicking off in Adelaide yesterday.

The vaccine was developed by researchers from Flinders University and Australian biopharmaceutical company Vaxine, a specialist in adjuvant platform technology, after the latter saw it as a public health imperative to respond to the threat of a pandemic.

“As early as January 2020 our modelling data identified that COVID-19 was a major pandemic threat that could potentially cause millions of deaths globally,” said Professor Nikolai Petrovsky, Chairman and Research Director of Vaxine. “Unfortunately our early predictions were spot on.

“Although international bodies resisted our early calls to call it a pandemic and downplayed the imminent threat, Vaxine immediately went into overdrive to develop a vaccine against the impending COVID-19 pandemic.”

By February, Vaxine had already rapidly developed a variety of different COVID-19 vaccines, including DNA, mRNA and recombinant protein versions, but quickly concluded that the recombinant spike protein approach, which mirrored Vaxine’s earlier SARS coronavirus vaccine approach, provided the most certain and reliable results when combined with the company’s non-inflammatory Advax-CpG55.2 adjuvant.

“Past experience with adenovirus-based vaccines has shown disappointing protection and high toxicity, and DNA and mRNA type vaccines have their own problems, including being unproven technologies that may still turn out to be poorly scalable or have unexpected side effects,” Prof Petrovsky said. “Low immunogenicity of adenovirus, DNA and mRNA technologies in particular could be a major problem when it comes to coronavirus vaccines, where immunity will need to be strong and long-lasting.

“Most of these vaccine technologies are unable to benefit from adjuvants, which are the key turbochargers that are bolted onto protein-based vaccines to dramatically enhance their effectiveness.

“This, along with exceptional safety, tolerability, manufacturing scalability and a proven regulatory pathway, is why Vaxine chose to go with a recombinant spike protein approach for COVAX-19 vaccine.”

Computer-simulated model of COVID-19 spike protein binding to the human ACE2 receptor through which it gains entry into cells lining the human lung. Vaxine’s COVID-19 vaccine is designed to mimic the portion of the spike protein attaching to ACE2, with the aim of inducing human antibodies that will bind to the COVID-19 spike protein thereby blocking it from binding to ACE2 and getting inside human cells, thereby preventing infection.

The company’s Phase 1 trial will provide initial safety and immune response data on COVAX-19 and is being conducted by the PARC clinical trial unit at the Royal Adelaide Hospital (RAH). 40 healthy participants, aged between 18 and 65 years, will receive two doses, three weeks apart, of COVAX-19 or a placebo injection. They will then have blood tests to measure protective antibody and T cell responses induced by the vaccine.

“This COVID-19 vaccine has already shown promising results in animal models, so it is exciting to take this national breakthrough to human trials in Adelaide,” said Flinders University Professor David Gordon, principal investigator on the project.

“The development of antibodies and other immune responses will be determined two weeks after the second injection, so the results of the first trial will be available in around two months’ time.”

After health checks are run on the first volunteer, the other participants will be called in to receive the vaccine at PARC Clinical Research at the RAH. After assessments, Phase 2 clinical trials will be scheduled for further testing.

Image caption: Vaxine’s promising new COVID-19 vaccine candidate.

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