Cosmos Q&A: vaccines, antivirals and why you should get a jab

Australia’s COVID vaccination program has been announced and will soon begin. While most people welcome COVID vaccines, concerns linger over the speed at which they’ve been created and the new technologies used in their development. We asked Dr Rob Grenfell, CSIRO’s Health Director, Health & Biosecurity, to tell us about COVID vaccines (and other treatments) and explain why it’s a good idea to get vaccinated.

Is it right to say that vaccination is the only thing at our disposal for fighting viruses long term?

One of the cornerstones of managing any infectious disease is public health measures, such as case detection and isolation, personal hygiene and social distancing. We have seen how effective this can be in Australia with significant control of the SARS-COV-2 virus and its spread during this pandemic.

There are three other major weapons in our arsenal against viruses: vaccines, antiviral drugs and diagnostic tests. A safe and effective vaccine is one of the best defences against COVID-19, but certainly not the only one.  

Antiviral drugs can help reduce the severity of disease caused by SARS-CoV-2 and lessen the pressure on our health systems. The HIV and Hepatitis C epidemics have been effectively controlled by public health measures and medications. 

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Rob Grenfell, CSIRO Health Director, Health & Biosecurity.

Diagnostic testing is also critically important in containing the spread of a virus. It helps authorities determine who’s infected, who’s infectious and where the cases are. Wastewater testing in Australia has provided an early warning system to help identity COVID-19 cases in the community.  

Even as a vaccine is rolled out, ongoing diagnostic testing will be crucial in supressing further spread of disease while immunity is built up in the population.  

Have any other medical interventions proved efficacious in treating people who contract COVID, and how do they compare to prevention methods such as vaccination and isolation? 

Antiviral treatments have a crucial part to play in our ongoing management of COVID-19. In the case of HIV/AIDS, while an effective vaccine has not been found, “antiretroviral” drugs were developed to treat the disease. They work by stopping the virus from replicating in the body and allowing the immune system to repair itself and prevent further damage. 

Hundreds of trials are underway globally to evaluate potential antiviral treatments for COVID-19.  

The speed with which COVID vaccines have been developed has prompted discussion, and possibly hesitation, in people who’d ordinarily have no issue with vaccination. Compared to other medical trials, why was it so much faster to make COVID vaccines than other vaccines? 

Scientists had a head start in fighting COVID-19 thanks to existing research and knowledge of SARS, another type of coronavirus that broke out in 2002–3. The severity of the pandemic has also led to unprecedented levels of scientific funding, focus and collaboration, allowing vaccine developers to leap into action.  

It’s important to note that the timelines for vaccine trials have remained the same — no shortcuts were taken around scientific rigour, safety or quality. Given the emergency situation of a public health emergency of international concern, some clinical trial phases were conducted concurrently.  

Some countries started manufacturing vaccine candidates in anticipation of regulators assessing the candidates, such that a supply of the vaccine would be ready if regulators granted approval or emergency authorisation. This was the case with the Pfizer vaccine, which was ready for deployment as soon as emergency use authorisation was granted in the UK.

The regulators began working with the clinical trial agencies and manufacturers prior to trial completion. Usually, they will wait for a formal application after all trials have been completed. This is an exacting process and is typically the major cause of delay in the eventual release of any vaccine to general use. This step is very important in ensuring the safety and efficacy of the vaccine. 

How safe are vaccinations generally – and the COVID vaccines that will be used in Australia in particular? How do vaccinations compare for safety and side-effects to antibiotics, for instance? 

This is a difficult question to quantify an answer to. There are many different types of vaccine, with differing mechanisms of action, similar to antibiotics. Because of this there is a wide range of safety and adverse events across both vaccines and antibiotics. Therapeutics that have been approved by regulators are given parameters for their clinical use, the so-called approved use. This also outlines the side-effect profile and the clinical use cases. The vaccines and antibiotics in general use are deemed safe by regulators and have documented well known side-effects.  

What is the difference between mRNA vaccines and “traditional” vaccines, or DNA vaccines such as AstraZeneca? How do they compare in terms of safety? 

mRNA is a new vaccine technology where a genetic material resembling specific proteins on the virus surface stimulate the immune system to generate antibodies. Pfizer and Moderna are examples of mRNA vaccines. 

The AstraZeneca vaccine is on an attenuated viral vector. That is a virus that has been selected that will infect the host, but not cause an illness. By tagging the viral vector with specific proteins from the COVID virus it is possible to stimulate immunity against SARS-COV-2 in the host. 

The safety profile of mRNA and DNA vaccines are comparable, based on phase III clinical trial results. 

Will vaccines based on genetic material become more common in the future?

The success of the mRNA vaccines in this current pandemic have demonstrated the value of this technology. Further science in this area will lead to novel vaccines against infectious disease. The mRNA vaccine technology has shown some early experimental success in the management of some cancers such as some blood cancers and melanoma. 

What are the risk/reward questions that need to be answered when administering a vaccine under emergency conditions? 

We are in the grip of a global pandemic, with quite a long way to go. Worldwide there have been over two million documented deaths, with many uncounted. The virus can cause protracted damage to survivors, with damage to the lungs, heart, kidneys and nervous systems already documented. So, the stakes are high. 

Relative to the unfolding situations in US and Europe, Australia is in a somewhat fortunate position to have community transmission of the virus under control. The consideration of whether or not to grant emergency authorisation to vaccine candidates is therefore not as pressing as in other countries. Our independent regulator, the Therapeutic Goods Administration, is in the process of rigorously assessing clinical trial results in order to determine approval (or not) for vaccines.  

What are the benefits and disadvantages of administering two different types of vaccines, such as is proposed in Australia? 

After development, manufacture and approval of vaccines, the next challenge is supply. The whole world needs a vaccine and producing enough is a major challenge, with an array of logistical issues to overcome. Australia is fortunate to have secured 10 million doses of the Pfizer vaccine with which to commence the immunisation of high-risk groups. We are also fortunate to have the capability in Australia to manufacture to-scale the AstraZeneca vaccine. The supply of vaccine is also compounded by the transport requirements, which can limit the availability. Having multiple vaccines — including one that is logistically easier to manage — should help with a smoother and swifter roll out of vaccinations. 

What’s the risk of coronavirus mutating enough to overcome a vaccine? 

As we have seen during this pandemic, various sub-types of the virus are emerging that are more infectious. This is to be expected because, as we limit the chance of spread through public health measures, more transmissible virus sub-types start to dominate. 

While it is normal and anticipated for RNA viruses to mutate, the SARS-CoV-2 virus has a “proof-reading” mechanism which limits the rate at which it can mutate. So far, the majority of the virus’ mutations have not had an impact on vaccine efficacy, but this is something that scientists are watching closely.

There’s been coverage of potential vaccine side-effects, and of volunteers who weren’t able continue in trials. This appears to have had an impact on public perceptions. What does this data mean in the context of a scientific study/paper and how do they relate to vaccine safety? 

All therapeutics have a side-effect profile. The scientific process involves quantifying the degree and severity of side-effects and assessing that against how effective the vaccine is in controlling the disease.  

Some, perhaps many, of the large pharmaceutical companies that have participated in COVID vaccine development don’t have fabulous reputations. Why should we trust the work they’ve done? 

Australia’s Therapeutic Goods Administration is one of the most stringent independent regulatory authorities in the world. Part of the scientific and regulatory process is to ensure the safety, quality and effectiveness of vaccines that are released in Australia. Vaccine developers and pharmaceuticals companies will have to put their candidates through this rigorous process before a vaccine can be approved for use. 

Aside from discussion specific to COVID vaccines, there remains a cohort in society who are against any vaccine. Nationally, vaccination coverage rates for Australian children runs above 92% so we can assume this cohort isn’t large, but any growth in vaccine scepticism surely wouldn’t be helpful. As a scientist, what do you say to those people who are generally accepting of vaccination but somewhat hesitant in the case of COVID vaccines? 

The choice to be vaccinated should be made on sound logic and reliable evidence, this includes: 

Your general health – the elderly and those with pre-existing health conditions, when infected with COVID are more likely to experience dire consequences. My opinion as a scientist and doctor is that vaccination in these cases in absolutely critical. 

The vaccines approved to date all reduce the likelihood of severe disease. This is certainly a result that would allow you to re-emerge with the confidence that you are safe from hospitalisation from COVID. It will still require adherence to the public health measures to avoid any potential spreading of the virus to others, if you are carrying it. But it will mean that you could re-establish a range of your previous activities. So, if you wish to roam around the community with a greater degree of safety; go to movies, go to entertainment venues, travel and so on, then a vaccination is suggested. 

Effective vaccines will increase immunity. The more people who become immune, then the less likely the disease will spread to those who could die from it. On that basis, you could argue that being part of a community response is a moral imperative. 

Related reading: COVID vaccines: where the bloody hell are we?

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