Our virology expert answers questions about the quest for a coronavirus vaccine.
Federal Minister for Industry, Science and Technology, Karen Andrews, recently reported on the status of three coronavirus vaccines and Australia’s ability to manufacture these at the capacity required to vaccinate our population.
So what are the three vaccines and how do they work? What issues impact our vaccine manufacturing capacity? And is anyone testing a vaccine for children? Virology expert Professor Eric Gowans explains….
Read also: Debunking the myths about a COVID-19 vaccine
Minister Andrews mentioned the Oxford vaccine, the University of Queensland (UQ) vaccine and a messenger RNA (mRNA) vaccine. What is the difference?
All three vaccines are designed to induce ‘neutralising antibodies’ to COVID-19. Therefore, all three vaccines include the Spike protein that is vital for the virus infection process.
Many studies have shown that these neutralising antibodies can prevent infection, although the level of antibodies needed to circulate in an individual in order to be protective is still unknown. We hope that the current Phase 3 clinical trials will provide this information.
Minister Andrews also said Australia currently does not have the technology to manufacture mRNA vaccines. Should we be worried?
Although these three vaccine strategies are fairly well-developed, none is currently licensed for use in humans and not in general use. Therefore, the Minister is correct to suggest this. The development of these vaccines depends on skilful molecular biology (genetic engineering) which is readily performed on a laboratory scale but not so readily scaled up to generate the millions of doses which will be required worldwide.
The technology behind the Oxford vaccine is well established while the UQ vaccine (called molecular clamp) and the mRNA vaccine are more recent developments. All three are designed to deliver the Spike protein to cells of the immune system with an injection in the same way we deliver the flu vaccine. However, the manner in which the Spike protein is presented to the immune system differs.
I haven’t heard of the mRNA vaccine before – what does it entail?
mRNA vaccines are relatively recent developments in the vaccine field and are currently in development against infectious agents and cancer.
There are two major mRNA vaccines in development for COVID-19, including the Moderna vaccine, which depends on a similar principle to the others but produces a slightly different form of the Spike protein. In each case, the vaccine is reliant on genetic engineering of DNA to contain the gene for the Spike protein, flanked by upstream and downstream genetic control elements.
Are there any other vaccine strategies?
The three vaccines we’ve discussed represent only a fraction of the strategies currently in the experimental stage. The other strategies include conventional methods such as using the whole inactivated virus, a weakened live virus, and also DNA vaccines.
THRF awarded a grant to Dr Branka Grubor-Bauk at the Basil Hetzel Institute to investigate COVID-19 infections in South Australia and this funding encompasses the design and synthesis of a DNA vaccine (although more funds will be needed to perform the necessary pre-clinical studies).
What other issues may impact on our capacity to produce the required vaccines?
Current strategies to develop an effective COVID-19 vaccine are dependent on two doses of the vaccine at 4-6 week intervals. This obviously increases the pressure on vaccine manufacturing capacity.
It is likely that CSL has the capacity to manufacture the UQ or the Oxford vaccine, but may be unable at present to manufacture a mRNA vaccine.
However, we should not underestimate the capacity of the vaccine industry to develop a manufacturing strategy for any vaccine that is shown to have an advantage over others!
It has been stated that the vaccine rollout will (rightly) target health workers and vulnerable people first. But this made me think, has anyone been investigating a vaccine for children?
Children largely present as asymptomatic to the virus so they have not been the priority of global vaccine work.
It is likely they will be the last population cohort to be vaccinated, as once a vaccine is determined to be safe, more trials will be needed to determine the appropriate vaccine dose and immune responses in children.
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