Pfizer is claiming 95 per cent effectiveness against COVID-19 and close behind it is the Moderna vaccine, with a similar claim of 94 per cent effectiveness.

Both use a breakthrough technology called mRNA (or messenger RNA), which encodes genetic instructions for human cells to make a harmless part of the coronavirus spike protein in order to prime the body’s immune response.

Professor Ian Frazer warns it’s going to be a five- to 10-year exercise getting a sufficient level of vaccination across the world.

Professor Ian Frazer warns it’s going to be a five- to 10-year exercise getting a sufficient level of vaccination across the world.

But let’s return to Kelly’s friend’s daughter. To gain the maximum protection from the Pfizer jab, she’d have to get a second jab three or four weeks after the first (as will also be the case for nearly all the vaccines now under development).

And while that might well protect her from developing the disease of COVID-19 if she caught the virus, it is far from clear whether she’d cease to be an infection risk to others.

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Indeed, warns vaccine researcher Professor Peter Richmond from the University of Western Australia, that remains “one of the biggest unknowns – whether these vaccines will interrupt transmission”. And it remains an unknown for all the vaccines now under development, with a definitive answer many months away.

For those dreaming of an “immunity passport” – something that lets you swan through airline check-ins because you can produce proof of having had a shot – the uncertainty about whether you remain potentially infectious once vaccinated is a major impediment. “It’s the cart getting ahead of the horse,” says Richmond. “It’s just too early, we don’t have the data to support how it might work.”

It’s also far too early to say how long the protection conferred by Pfizer or the other leading contenders might last. That could vary depending on the type of vaccine a person had received – again an unknown that could take months to clarify.

Currently there are five different vaccine technologies being used by researchers to develop vaccines against the SARS-CoV-2 coronavirus, of which mRNA and DNA vaccines are the newest.

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According to Queensland University’s Professor Ian Frazer, one of the country’s most eminent immunologists, “each has their advantages and disadvantages ... That’s why we are using at least five different technologies, because we don’t know in the long run which is going to be the best”.

There remains the possibility of rare side effects coming to light once hundreds of thousands or millions of people – as opposed to groups of 30,000 in heavily monitored clinical trials – start receiving coronavirus vaccines. Any such scares could delay rollouts or trigger new safety trials.

The mRNA vaccines are the “new kids on the block” says head of the NSW Immunisation Specialist Service and Sydney University researcher, associate professor Nicholas Wood. “Unlike protein- based inactivated viral vaccines we don’t have a huge amount of experience with them. That’s why there will be very robust safety surveillance systems that each country will have to develop.”

And as yet none of the vaccines have been tested on children, who can also transmit the virus although not as readily as adults.

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Then there’s the challenge of so-called vaccine hesitancy from those yet to be convinced of their safety, something the federal government is set to combat with health minister Greg Hunt’s announcement on Thursday of a $23.9 million information blitz which will include a national advertising campaign.

Australia has a purchasing agreement for 10 million doses of the Pfizer vaccine, along with 53.8 million doses of a viral vector vaccine developed by AstraZeneca and Oxford University, and 51 million doses of a protein vaccine now being trialled by US-headquartered Novavax.

But AstraZeneca has encountered delays in winning regulatory approval in the US because of confusing data which showed participants in its trial benefited more from an accidentally-administered lower dose than from the full dose. It is still hoping for approval to proceed in the UK, Canada and India in coming weeks.

Meanwhile the fate of the homegrown vaccine which had been under development by a team at the University of Queensland is another sobering illustration of how high hopes can come to grief at the final hurdle.

The UQ product, based on a unique “molecular clamp”, had incorporated a small fragment of protein from the HIV virus in its design. But the venture had to be abandoned when it was discovered that participants given the trial vaccine started returning false positives to HIV tests. It came as shattering news to the UQ team who had worked long hours over months to develop the product, though the government says it will continue to support the UQ research because the work still holds promise.

Richmond says “it really shows that producing a vaccine rapidly for any disease, but particularly COVID-19, is a difficult process and there are a number of steps where you can run into problems that may or may not be addressable”.

Prime Minister Scott Morrison at the University of Queensland. The vaccine venture had to be abandoned when it was discovered that participants given the trial vaccine started returning false positives for HIV tests.

Prime Minister Scott Morrison at the University of Queensland. The vaccine venture had to be abandoned when it was discovered that participants given the trial vaccine started returning false positives for HIV tests.Credit:AAP

Another challenge which could emerge - even for the successful first crop of vaccines - is the risk of the virus mutating over time to weaken or negate the protective effect of vaccination.

Sydney University virologist Professor Edward Holmes, who first published the genome sequence of the SARS-CoV-2 virus earlier this year, says RNA viruses (of which the coronavirus is one) “mutate all the time, it’s what they do for a living”.

“Eventually as immunity builds up [in the population] there will be selection pressures on the virus for variants to escape that immunity,” he tells the Herald. “I suspect we will be able to get through the first vaccination program without that happening. But it will happen and then we will have to update the vaccines every so often; I think that’s completely predictable.”

Last week reports emerged from the UK of a more infectious “strain” of the virus circulating in south-east England although so far there is no evidence that it is more virulent or likely to be able to dodge the vaccine.

Sydney University virologist Professor Edward Holmes.

Sydney University virologist Professor Edward Holmes.Credit:Louie Douvis

Kelly went to some pains this week to hose down any concerns, saying information so far out of Britain was that it was a “minor change, not a major one” and did not “appear in any way to affect the effectiveness of the vaccines″⁣.

For the world as a whole, equitable access for poorer countries remains both a public health and a moral challenge. The new mRNA vaccines are not a good solution for those nations as they are more expensive and need to be kept at low sub-zero temperatures, a logistical challenge in the developing world.

There is also mounting concern that richer nations have been able to bag the lion’s share of what are still limited stocks, until such time as manufacturing can be ramped up at multiple sites around the world.

A recent analysis published in the British Medical Journal found that 51 per cent of pre-market purchases (amounting to 7.5 billion doses) of coronavirus vaccines have been reserved for high-income countries, which account for only 14 per cent of the global population.

Frazer warns, “if we are talking globally it’s going to be a 5- to 10- year exercise to get sufficient level of vaccination across the world; we have never immunised even a whole cohort of people of one age across the planet before, and now we are trying to immunise all nine billion of us. It’s a huge, huge logistic task”.

He is hoping new antiviral drugs will emerge as an additional weapon against COVID-19, because “the virus will continue to circulate in the community, and people who are not fully protected by the vaccine will continue to get sick”.

He says there will be “stepwise progression” towards a next generation of vaccines because “we have all these wonderful technologies at our disposal now, and are so much better prepared than we would have been 50 years ago. We will continue to use these to develop better methods still to protect against this virus and hopefully against whatever comes next”.

But the new normal, he says, “is not going to be the old normal for the foreseeable future.”

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