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Introduction
Hello curious people. I'm Associate Professor Jane Frawley, a maternal and child health expert with a focus on immunisation and infectious diseases. I'm here to answer your curious questions about the spread of disease, pandemics, and how we can help to protect each other. This is Health Curious.
Our UTS community have sent in some thought-provoking questions to tackle. Let's get started.

Is it a case of when, not if, for the next pandemic?
Is it a case of when, not if for the next pandemic? Yes, absolutely. Pandemics have been part of our human experience forever. In the last hundred, 120 years, we've had six pandemics.
So we had three pandemics between 1918 and 1968, we had an HIV pandemic in 1981, a swine flu pandemic in 2009, and then, of course, Covid-19 in 2019.
In the last 23 years we've also had SARS, MERS, Zika and Mpox. They weren't pandemics, but they had the potential to be pandemics. So yes, it's definitely a case of when and not if.

What do you think are some of the biggest lessons from Covid-19?
Wow. It's hard to know where to start with that because there were so many lessons. But I think for me, the biggest lesson was how much we can achieve when we work together.
So for example, from first identifying the virus and characterising the virus very quickly through shared experience across borders so that vaccines could be made, and then in vaccine production, vaccines were made in an incredibly expedited fashion.
But this was only because of the resources that were given to that production at the time, which meant that different phases of production could be done at the same time rather than one after the other, which is what normally happens.

How does a vaccine work?
This is a great question. So our bodies have this unusual hack, if you like. Where if we've experienced an infection, our immune system remembers that infection, and we are unable to contract that disease again or we can only ever get a very mild form of that disease, meaning it can never be fatal.
So vaccines work by tricking the body into thinking that it's had the disease. A vaccine will use a very, very tiny amount of a bacteria or a virus. This is always weakened. Sometimes it's only part of a fraction of the virus, for example, or sometimes it's weakened in another way with heat.
But it's enough to trick the body to think that it is actually the real infection, to fight that infection and to make antibodies that last. That means that you can either never get that infection again, or you'll get a very mild dose of that illness.

What is herd immunity? What does it take to achieve it?
So herd immunity refers to the number of people in the community that need to be vaccinated in order to protect everyone in that community.
So if this is our community and all of these people are immunised and for some reason this person isn't—let's say that they're too young to receive a measles vaccine, or perhaps they're a really small infant and they're too young for whooping cough vaccine—then we need to protect them with herd immunity.
So that means that if the vast majority of people in the community are vaccinated, then there's almost no opportunity for the virus or bacteria to move from person to person and to essentially find and infect someone who hasn't been immunised.
For something like measles, we need a very high number of people to be vaccinated in the community. It's 95%, and that's because measles is an incredibly infectious virus.
If I was in a room and I had measles and then I left that room and you walked into that room an hour later, up to two hours later, you would have a 90% chance of catching measles.
So you can say that it's an incredibly infectious disease that we need to keep out of our communities. So we have a rate, if you like, of 95% around the world that we aim to achieve, to keep measles out of our communities.
So unfortunately, since Covid, uptake of some vaccines like measles has dropped a little bit. So measles uptake for two-year-olds in Australia at the moment is sitting around 92 to 93%, which is a little bit less than we would like it.
This isn't unusual in terms of it has happened all around the world. It happened largely due to the pandemic, due to stockouts, public health orders, border closures, etc. and of course, some people also being reluctant or, I guess, a little hesitant to immunise their children after hearing some of the misinformation about the Covid vaccine.
We're largely back on track in many countries of the world and improving vaccine uptake, especially for children. But there's still a little way to go.

It seems like we get a lot of vaccines, especially as kids. How is the vaccine schedule developed?
This is an excellent question. So vaccine schedules are developed based on very close and detailed analysis of risk versus benefit—so the risks associated with the disease itself compared with the risks associated with the vaccine, which means side effects of the vaccine.
Infants, children and adults are vaccinated when they're most at risk. Childhood and infancy is a period of time when you're most at risk for the majority of vaccine-preventable diseases.
So diseases like whooping cough, diphtheria, tetanus, polio, measles, rubella, for example, are deadly for children. So these vaccines are on the schedule from very, very young. In some instances, there's a birth dose of a vaccine—so for example, Hepatitis B—but then vaccines start routinely at around six weeks when the infant is still quite small. And that is to protect them when they're out and about in the community.

Why do some people choose not to vaccinate their children or themselves?
About 5% of parents choose not to vaccinate their children in Australia. So it's really important, I think, to keep this in perspective. It's actually quite a small number.
And for many of those parents they have questions about the safety of vaccines and maybe also the need for vaccines.
Vaccines in many ways have been a victim of their own success. And there's many diseases that we commonly vaccinate against in Australia that we don't see in our communities anymore—for example, polio.
So for many parents, they may feel that those diseases aren't really a risk anymore in their communities and perhaps have concerns around the safety of vaccines and therefore think that perhaps the risks may outweigh the benefits for their child.
The diseases, of course, are only at bay because high numbers of our communities are vaccinated. These diseases really do still exist, both in Australia and overseas. So immunisation and herd immunity is incredibly important.
It’s very normal to have questions about vaccines. It's normal to have questions about any medicine or medical procedure. And it's important that you find someone to talk to about this and have an open and frank discussion with a health care provider, with your GP about your concerns.

How do I know I can trust a source of information about diseases and vaccines?
You always need to check the source of information. Is it credible? Is it reliable? Who is it? Do they have any particular agendas? Is it evidence based? Is it a government website? Is it a different type of website?
And I guess also, how in line with the scientific information and that knowledge about diseases and vaccines is the information that you're receiving?
If it's very different, it's probably worth having a very close look at the sources and to see if it's credible.
It can be really hard, especially on social media. So social media, of course, is a really common way that we all communicate. And often we're receiving messages about immunisation that can be good and they can be bad.
But sometimes the misinformation can be really amplified on social media. So it's always really important to check.

That was all the questions for today. I hope you learned something new. Until next time, stay curious.