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20 Aug 2020

COVID-19 Vaccine: Are we seeing the light at the end of the tunnel?

By University of Melbourne Professor Dale Godfrey, Immunology Theme Leader at the Doherty Institute

This article was originally published in the Herald Sun

Almost eight months into the pandemic, COVID-19 has infected more than 22 million people and claimed almost 800,000 lives. We all bear the scars of this virus in some way, shape or form, as we wait with bated breath for a vaccine to put an end to this suffering.

Fortunately, many of the world’s scientists are laser focused on vaccine research and development to tackle this disease. Research teams, institutes, universities and pharmaceutical companies globally have seen unprecedented progress over the past eight months, with more than 200 vaccines in development and over 30 already in clinical trials. Some of these have already reached the crucial stage of phase III clinical trials; a clinical trial that follows phase I and phase II trials for safety to inform us about how effective these vaccines are at protecting us against COVID-19 disease. This is science moving at lightning speed.

One of the leading vaccines is the Oxford University-derived ChAdOx1 vaccine, supported by the pharmaceutical company Astra Zeneca. Australia is now exploring an agreement to produce 25 million doses of this vaccine locally in association with pharmaceutical company CSL, and production could begin in the next few months. This vaccine, like several others, has shown very encouraging results from phase I and II clinical trials, generating immune responses in people that should provide at least partial protection against the virus. Based on results from early phase trials, the ChAdOx1 vaccine seems to be generally well-tolerated, with only transient, minor to moderate side effects that can be managed with paracetamol. An advantage of this vaccine is that it may be effective after a single dose, which addresses the difficulties of vaccine deployment if people don't return for the second booster injection.

Normally, the production, testing and deployment of a vaccine takes many years. With COVID-19, the timeframe has been dramatically condensed down to months. The need for this rapid development is obvious, but it does mean that we are not as confident as we would like to be about how effective the vaccine will be.

Safety is the most important concern when producing a new vaccine. We are still gathering data about the safety of vaccines in clinical trials, however, the results have been reassuring so far. It is risk-benefit analyses like these that regulators such as the Food and Drug Administration (FDA) in USA and the Therapeutic Goods Administration (TGA) in Australia will be carefully weighing up as they try to determine if the vaccine is ready to be approved for general use in the community.

So, if the vaccine can provide protection against COVID-19 and can be successfully deployed, what next? For a vaccine to be protective for the entire community it is important that enough people are vaccinated to provide ‘herd immunity’. This is where vulnerable members of the community are protected by the fact that they are less likely to encounter the virus when people around them are immune. For a vaccine to protect our most vulnerable citizens from COVID-19 – such as those who are immunosuppressed and the elderly - estimates state that 70 per cent of people or more will need to be immune. To achieve this, the vaccine would initially be offered to healthy children, adults and the elderly - but may not include pregnant women and infants until further testing and assessments emerge.

As the world races towards a vaccine, there are still many unanswered questions remaining. One is an important question of how long immunity will last before we need a boost. Another is how to know who is immune and who is not. This may involve the use of “immunity passports” or “vaccine visas” where people use simple test kits to measure their immune status – perhaps a temporary requirement if indeed at all. The real hope is that COVID-19 vaccines will provide long-term protection that lasts for years, and that we will eventually add COVID-19 to the list of diseases that we can keep under control as we get back to life as we knew it.

Despite the many unknowns, there are important lessons on what can be done when scientists, governments and industry collectively focus on a problem. As a scientist, my hope is that we can focus the same attention and energy to other critical problems that are no less important. Diseases - such as dengue, malaria, tuberculosis, cancer and cardiovascular disease – and the challenge of anthropogenic global warming still await us. As we look to the light at the end of the tunnel with a COVID-19 vaccine, the world is witnessing the incredible power of working together towards great change. This may be the most important lesson for us all.