Top 3 with Dr Lucas De Toca – Flu vaccination, what is in it and how safe it is

Dr Lucas De Toca, COVID-19 Primary Care Response First Assistant Secretary, answers the Top Three questions across our channels.

Date published:
General public

Hello, I'm Dr Lucas de Toca, and I lead the vaccine rollout for COVID-19 for GPs, pharmacies and Aboriginal health services. But today, again, we're talking about flu. I had my flu shot yesterday, and more and more people are getting their flu shot every day. So, it's really important that we answer some of your questions about flu vaccination as we approach winter. First of all, I'd like to acknowledge the Ngunnawal Dhawura and pay my respects to the Ngunnawal people, and thank them for having us here on their land.

I also want to acknowledge that it's International Nurses Day today, the 12th of May. Nurses are the backbone of the health system. There's more than 450,000 in Australia, and have played an absolutely vital role throughout the pandemic, keeping us all safe, staffing the testing centres, doing the majority of the vaccinations. So, I want to thank all nurses for the incredible work they do. Encourage that you reach out to your colleagues who are nurses, to your friends and family, and thank them for the work they do. And you can go to the website of the Australian College of Nursing to access resources and see some events to celebrate this very, very important day. Thank you to all nurses. We can't say it enough.

So, today we're going to talk about what's in the flu vaccine. How do we decide what virus strains we put in them, also what the ingredients are. And if you look at a list of ingredients of pretty much anything, it can sound pretty scary, but it doesn't have to be. And we're also going to talk about whether the vaccines are safe. So, first of all, virus, and the flu virus is no exception, mutates. And when viruses mutate, new strains, variants, versions come up. And we all know that too well with all the talk about variants with COVID. But flu is a virus that generally mutates on a seasonal basis, and there's several strains of influenza A and influenza B, the viruses that cause the flu, that cause a flu season in one hemisphere, generally during winter. And then once people who could get infected, get infected and the epidemic stops, then they cause a flu season on the other hemisphere, normally in time for their winter. And when that happens, the virus can mutate, which means that by the time it comes back for the following flu season, it could be different. So, the World Health Organisation assembles a group of experts in February and September every year that look at all the circulating cases of flu in both hemispheres and what strains are becoming dominant and the most common ones. And based on that, make recommendations on what specific strains of the virus are or what specific components are, put in the vaccines to fight the specific strains of the virus that we expect are going to be predominant every year. And that's why the effectiveness of flu vaccines changes from year to year because it's a bit of an arms race between what strain it's going to be the main one that is going to impact us on this season, and is that the one that we put in the vaccine at the beginning? So far, although it's early in the season, it seems like the match between the four strains that we are getting protected from with the flu shots this year and the strains that we are seeing circulating in Australia causing infection are a good match. So, it's probable that 2022 is going to be a good vaccine year, in which vaccines are going to be more effective. They're always effective, but the effectiveness varies. So, once the WHO makes those recommendations, the TGA does their own assessment, as always, the Therapeutic Goods Administration, and then there's a decision on which different strains go into the vaccines that will be supplied as part of the national immunisation program in Australia to cover for two variants of influenza A and two variants of influenza B. And like any other vaccine, what that does is exposes components of that virus to your body so that your natural immune system can learn to recognise it, mount up a response, generate antibodies that attach like sticky to the virus. And then if, 2 to 3 weeks after you get the vaccine, you get in contact with the actual virus, you're already armed with the immune arsenal to fight it. Like all vaccines, it's not 100% effective at preventing infection, but greatly reduces chances of getting it. And then even if you get it, because you already have the tools to fight it, the chances are you will have a much milder course than if you weren't vaccinated. Vaccines also contain adjuvants and other substances that help both the immune system recognise the component of the virus that you want to expose your body to, but also keep it stable, make sure that it doesn't break down and make sure that it can do its job. So, when you look at a list of vaccine components, or vaccine ingredients, it can be a little bit daunting. However, if you look at a list of ingredients, pretty much anything that you buy in the supermarket, it also can sound pretty daunting because there's a lot of numbers and names that sound pretty chemical. So, I think we need to take a step back and think of what some of these things mean.

So, for the second part today, I thought we would explain some of those components and what they do and do not mean to make sure that you have all the information that you need, but also that it's not taken out of context because there's always a lot of noise around vaccines. So, you will have heard that vaccines contain traces, flu vaccines may contain traces of egg protein. That's because flu vaccines are manufactured, are grown using fertilised chicken eggs where the viruses grow and then we extract the components that make the vaccine. Even though that's pretty thoroughly cleaned and removed before the later stages of the vaccine manufacture, it can contain traces of egg-related proteins. So, while the vaccines are generally safe for people with egg-related allergies, it is rare, but possible, that people with egg-related allergies get a reaction from a flu vaccine. So, if you have an egg-related allergy or you're worried about that, have a chat to your regular GP, your health professional or your immunisation clinic before you get your flu shot and you can talk about options. Then, you will have seen that vaccines contain very small amounts of formaldehyde. And that's a substance that sounds scary, sounds nasty. But formaldehyde is a product that is generally produced in our metabolism. It's in all of our bodies as part of the regular function of the cell. In really high levels of external exposure over a long time it can be harmful, but the traces of it that are present in vaccines, which are not more relevant than what you already have in your body, there's no risk from the formaldehyde in the vaccine. And it's used to make sure that there's no contamination of the vaccine itself during the manufacturing process. It's good at eliminating toxins and making sure that while the vaccines are being made, you don't get nasty viruses or bacterias contaminating the product. You might have heard some noise about mercury, and a substance called thimerosal containing in the vaccines as a preservative. Mercury, especially in large quantities, is very toxic. The influenza vaccines, the one that we have in this season in the National Immunisation Program and privately in Australia do not contain mercury. So, please do not listen to that if there is a concern on that. We also use stabilisers, which are substances that make sure that the active components, the bits of the vaccine that actually help your body recognise the virus, can survive transport, exposure to light, changes of temperature, and those stabilisers are most commonly sucrose and sorbitol. Again, chemically sounding names, but sucrose is sugar, the sugar that you have on your table and that some people put in their coffee, that's sucrose. And sorbitol, it's also used very commonly in food as a sweetener. And in fact, if any of you are chewing sugar-free chewing gum, that's got sorbitol. And again, these substances that help the active component of the vaccine remain stable are in very, very small amounts. So, they're not a concern for people who have sugar restrictions or diabetics. You might have heard as well that the vaccines can have traces of antibiotics like neomycin, gentamicin and other antibiotics. The vaccine manufacturing process includes antibiotics to make sure that there's no bacterial colonisation, that there's not a contamination of the product. They are removed in the later stages, but there might be small traces, and that's why it's listed in the list of ingredients. Again, no concern from that, and all vaccines undergo a really rigorous process. Finally, you might have heard about Polysorbate 80. And I mean, we're going through all of this because if you look at that list of ingredients, have questions, we think it's much better that you actually know what these things do. Polysorbate 80 is an emulsifier agent. It just makes sure that the different components of the vaccine are evenly distributed within the solution, within the vial. It's also very commonly used in sauces. It's what helps emulsify things like mayonnaise.

So, it's nothing that should be of concern, I mean, that's pretty commonly used in many other products that are not medical and you use in your day to day living. So, after that list of massive numbers of ingredients, the ultimate question is, are the vaccines safe? And the answer is, of course, yes. The Therapeutic Goods Administration, Australia's medicines and drugs and therapeutic goods regulator, is one of the strictest regulators in the world and they would not approve a vaccine that is not safe and effective and of high quality to be used in our population. Millions and millions of people get flu vaccines. We estimate about 17 million people will get it this year. And this is after years and years and years of using these vaccines, just changing the strains that are packaged up every year. So, they're very safe and they can protect you not just from the flu, but also from some of the nasty secondary infections that you can get after a bad flu. If you have a bad flu, you can get pneumonia following that. You can get bronchitis when bacteria or other nasties colonise your respiratory system. And that can be quite serious. It can also make asthma much worse for people who have baseline asthma and trigger asthma attacks. The vaccines not only help prevent getting the flu but also reduce the severity, which in turn reduces the chances of getting any of these secondary infections. And that's why it's really important, particularly for young children, particularly for older people.

But our general advice for everyone, six months and older, to get your flu shot, to get it as early as possible 'cause it takes 2 to 3 weeks for it to take, to start to take effect, and of course, to also maintain your COVID-19 vaccination status up to date. So, if you are due for your booster, go and get it and you can get your flu shot at the same time. If you're due for your winter dose, go and get it. And you can also get your flu shot at the same time. Continue to practice the COVID safe behaviours that you've been, that we've all been doing for the last 2.5 years because they help with transmission of infections, particularly respiratory infections in general. If you have symptoms, even if you're negative for COVID and can stay home, please stay home. And that can help reduce the transmission of flu. Wash your hands frequently. Wear a mask if you feel like you're in an indoor space close to people and you wish to do so. And yeah, stay up to date with all your vaccines. If you need more information, please go to or the National Immunisation Hotline on 1800 671 811. Thank you for watching.

Top 3 questions

  1. Flu vaccination in readiness for winter
  2. How the vaccine is developed in Australia
  3. What’s in it and how safe it is.

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