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'Will you need boosters?': 10 of your most-asked vaccine questions answered

von Michael Doyle - Aug 26th 3,019 Views
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All around the world, teams of scientists are racing to develop a coronavirus vaccine.

Readers have asked us thousands of questions about the vaccine race.

Here are 10 of the most common questions.

Why don't we have vaccines for diseases such as malaria, AIDS and hepatitis C?

We have many vaccines, so it can come as a surprise to realise there are many diseases which do not have a vaccine to date.

There are multiple reasons for this, depending on the disease in question.

Let's use malaria as an example.

There have been many obstacles in the way of developing a malaria vaccine.

One of them, according to the US Centers for Disease Control and Prevention (CDC), is the disease's complexity.

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"Malaria parasites have a complex lifecycle, and there is poor understanding of the complex immune response to malaria infection," the CDC states on its website.

"Malaria parasites are also genetically complex, producing thousands of potential antigens.

"Unlike the diseases for which we currently have effective vaccines, exposure to malaria parasites does not confer lifelong protection."

Also, vaccines are very hard to develop.

Jerome Kim, director-general of the International Vaccine Institute based in South Korea, told Radio National's Geraldine Doogue .

In very basic terms, a vaccine is taken from the living disease, purified, then put through rigorous safety protocols before it can be produced.

Can you please explain in layman's terms how the abortion issue plays into the COVID vaccine?

who posted on social media warning about possible ethical issues with the vaccine being developed by scientists at Oxford University.

If it works, this is the vaccine the Federal Government wants to give to Australians.

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The Oxford University vaccine has been developed from a of line kidney cells from an aborted foetus dating back several decades, according to Professor Colin Pouton, from the Monash Institute of Pharmaceutical Sciences.

He said it was developed decades ago and had been widely used around the world.

"It's not like people are using a new cell line," he said.

"It's already there, so in many respects, the ethical issue is in history."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume.

Nick Coatsworth addresses ethical concerns surrounding a potential vaccine.

This has raised concerns with several religious leaders.

Anglican Archbishop of Sydney Glenn Davies said there were ethical questions about the potential vaccine.

"To use that tissue for science is reprehensible," Dr Davies told AM.

The WHO recently indicated that the COVID-19 pandemic would not last as long as the Spanish flu. Why?

Indicated is probably not the right word — "hoped" would be more suitable.

World Health Organization (WHO) boss Tedros Adhanom Ghebreyesus said last week that the COVID-19 pandemic could be shorter than the Spanish flu.

The Spanish flu pandemic lasted roughly two years from 1918.

Dr Tedros said advances in technology over the last century had put humanity in a better position to develop a vaccine.

"Of course with more connectiveness, the virus has a better chance of spreading," he said.

"But at the same time, we have also the technology to stop it, and the knowledge to stop it."

Are there other options like 'herd immunity'?

In the early stages of the pandemic, the idea of herd immunity was touted as a possible method to fight COVID-19.

The UK's chief science adviser, Sir Patrick Vallance, said on March 13 that one of "the key things" Britain needed to do was .

Herd immunity is the idea that if a large portion of the population get the virus and recover from it, they will become immune to it.

An outbreak eventually fizzles out because there are fewer viable hosts for the virus to infect.

However, show that, even in hotspots where there have been large numbers of cases and deaths in the last few months, less than 10 per cent of the population show evidence of an immune response from the infection.

The percentage of a population who need to be vaccinated to reach herd immunity using the basic reproductive rate (R0).

This is the average number of people that each person who catches the disease would naturally pass it on to without any medical or public health interventions

Numerous diseases have been eliminated in many countries thanks to herd immunity produced by vaccination program, including measles.

Take the example of measles, which is caused by a virus that has been around in humans for centuries. It is highly infectious — the R0 value is 15.

This means that, on average, one child with measles can infect 15 others. As a result, of people need to be resistant to the disease for a population to achieve herd immunity.

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Until such time, health measures including social distancing, wearing masks and washing hands are very important.

Have any safety trials of potential vaccines considered the effects on respiratory tracts?

Issues with the respiratory tract are some of the reasons a vaccine for any of the coronavirus strains has not been developed, according to the University of Queensland's Ian Frazer.

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There are several reasons why our upper respiratory tract is a hard area to target a vaccine.

"It's a separate immune system, if you like, which isn't easily accessible by vaccine technology," Professor Frazer told the .

Despite your upper respiratory tract feeling very much like it's inside your body, it's effectively considered an external surface for the purposes of immunisation.

"It's a bit like trying to get a vaccine to kill a virus on the surface of your skin," Professor Frazer said.

Ian Frazer and the late Jian Zhou's wife Xiao Yi Sun.Ian Frazer and the late Jian Zhou's wife Xiao Yi Sun. Professor Ian Frazer (right) worked on the HPV vaccine and thinks a coronavirus vaccine is unlikely anytime soon.( Supplied: European Inventor Award )

Your skin, and the outer layer of cells in your upper respiratory tract act as a barrier to viruses, stopping them getting into the body.

And finding a way to neutralise the virus "outside" of the body is very difficult.

Is the vaccine for immunity and for how long? Will you need boosters?

In short, we won't know until we know.

"My personal prediction — based on decreases in antibody levels in individuals infected with other types of coronavirus, rather than data from the current vaccine trial — is that we're likely to need yearly boosters, similar to annual flu jabs."

However, this potential vaccine is still being developed and there is no way to know its effectiveness until it has gone through all of the necessary tests.

An employee wears a mask, goggles and hairnet at the Brazilian trials for the potential coronavirus vaccine developed by Oxford.An employee wears a mask, goggles and hairnet at the Brazilian trials for the potential coronavirus vaccine developed by Oxford. Trials for the potential vaccine developed by Oxford University and AstraZeneca are being conducted in Brazil.( Reuters: Amanda Perobelli )

of a study that looked at people who had recovered from COVID-19 infection.

The research found levels of antibodies that can fight the virus peaked in the blood three weeks after people got sick, and then declined after as little as two to three months, in some cases to nothing at all.

This is important because getting sick and creating a good level of antibodies to a particular virus means your immune system is better able to fight the virus the next time you're exposed to it.

This could mean boosters are needed, if the antibodies do not last.

I'm allergic to eggs so can't have the flu vaccine. Will I be able to have the COVID vaccine?

Similar to the last question, we will not know until the vaccine (if there is one) is developed.

This issue was raised during the aforementioned interview with Geraldine Doogue on Radio National.

Emeritus Professor Ian Gust, from the faculty of medicine at the University of Melbourne, said every vaccine was different.

While some flu vaccines use eggs during testing, this does not mean that coronavirus vaccines would be the same.

"For most vaccines, the manufacturing process is unique for that particular project and that particular product," he said.

In short, for many new vaccines, developers will need to start from scratch.

I read that the tuberculosis vaccine is effective against other viruses too. Is it being investigated for use against coronavirus?

The tuberculosis vaccine, known as the Bacille Calmette-Guerin vaccine (BCG), has shown the ability to boost immunity against other infections.

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Executive director Professor Steven Wesselingh told the ABC in April that BCG is a common treatment for bladder cancer patients.

With this knowledge, a clinical trial was established in April to see if BCG could boost immunity for COVID-19.

More than 400 frontline health workers in South Australia took part in the trial.

SA Health and the Murdoch Children's Research Institute were partners in this trial, which is still being conducted.

The trial aims to test 10,000 healthcare workers.

What if there is never a working vaccine? How long will people stay in their own countries?

With no vaccine at the moment, the WHO has already advised countries to consider safe and effective ways to slowly increase international travel.

At the end of July, the WHO said bans on international travel could not stay in place forever.

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Essential travel for emergencies, humanitarian work, transport of essential personnel, and repatriation were the main reasons the WHO encouraged countries to increase travel.

In Australia, international arrivals have been limited to about 4,000 a week.

Prime Minister Scott Morrison said after National Cabinet on August 7 that there was no plan to change this in the near future.

"International travel constraints on inbound arrivals to Australia should be continued in their current form," he said.

"At some point, that might be able to be altered. But at this point we are not going to put any further strain on the quarantine arrangements around the country.

"That will remain in place now for some months."

Is it necessary to wait for a vaccine to revive the economy?

This is probably a question being asked by governments across the world.

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KPMG says that in the absence of a vaccine in the next two years, Australia's population in 10 years is projected to be 28 million rather than the 29 million forecast by the Australian Bureau of Statistics.

That prediction was made before the COVID-19 pandemic.

The $117 billion loss to GDP, on an ongoing basis, equates to an $80 billion drop in household disposable income — or $2,800 a person.

"What net overseas migration does is it gives us a demographic dividend," KPMG chief economist Brendan Rynne told 7.30.

"That enables us to reinvigorate our population with younger people into our workforce."

This is a big reason why welcoming back overseas travellers is being touted as an important step for the nation's economy.

However, as answered in the question above, there would need to be a risk analysis done for issues like these until a vaccine was found.