Do I need a COVID booster? What the science says

Sam Hawley: Hi, I’m Sam Hawley, coming to you from Gadigal Land. This is ABC News Daily. As we head into winter, the Government’s launched a fresh round of ads urging adults to get their COVID boosters. But there are differing views in the medical field over whether we all need another shot. Today, an epidemiologist on the next wave, and what the latest science says about protection against COVID.

Professor Tony Blakely: I’m Professor Tony Blakely, Melbourne School of Population and Global Health, University of Melbourne. I’m also the chair of the New Zealand Royal Commission, but what I say today is not representing them. And finally, I also do contract work for Moderna that I should declare.

Sam Hawley: Tony Blakely, many people might not have realised it, but we have been through a fourth wave of COVID.

Professor Tony Blakely: Well, the numbers keep on rolling, which is what you would expect because we’ve essentially got a virus whereby our immunity to it keeps waning over time, from previous infection or previous vaccination, and it will keep coming back in waves. For how long? We don’t know unfortunately, it’s really, really hard to predict these things, but we are slowly working our way out of this. We are becoming more resilient through a combination of vaccination and infection.

Sam Hawley: So we have a higher level of hybrid immunity?

Professor Tony Blakely: Yeah, absolutely. Hybrid immunity, which is whereby you’ve both been infected and vaccinated – hopefully vaccinated first because it reduces the severity of the infection – hybrid immunity has really been our pathway out of this pandemic, there’s no doubt about that. Why? Because natural infection actually gives you stronger and better lasting immunity. It’s not perfect. You still get waning immunity from previous infection, but it’s better, quote unquote, than the vaccines.

Government ad: Chances are you’re due for a COVID-19 booster.

Sam Hawley: Let’s look now at the government’s latest ad campaign, because last week they launched this and really encouraged people, I think, to get a booster shot.

Government ad: You can now top up your protection with the latest vaccine. Visit the website to book your free booster. The ball’s in your court.

Sam Hawley: For some people, if they’ve had all the shots available, that will be the fifth shot, so another booster shot. But, Tony, it’s a bit confusing, isn’t it? Because also last week the World Health Organisation came out saying it doesn’t think another booster is necessary, except for people in high risk groups. So who’s right?

Professor Tony Blakely: Well, I think you can make a case for both of them. Again, I sound like I’m sitting on the fence, but let’s work through the pros and cons. So let’s run the case for vaccinating, say, 60-plus-year-olds, or people with co-morbidity. Why does that make sense? Well, it makes sense because they’re the ones who, if given enough infection, that are most at risk of going to hospital and perhaps also dying from it. So, them being vaccinated is a good idea. I think that’s fairly… that stands up to to logic. However, you can also run the case for vaccinating all ages and encouraging them, but not making it mandatory. We published recently a paper, and it was really interesting: we compared 60-pluses getting vaccinated, 60-plus-year-olds, or 30-plus-year olds, and actually it was more cost effective to vaccinate all 30-plus-year-olds. Why? Well, not so much, because the 30 to 59-year-olds get a lot of protection themselves. But, even though the vaccines are not perfect, they help reduce the transmission and therefore act as a sort of indirect protector for the elderly people and those with co-morbidity. So, on that ground alone, if I was the Chief Medical Officer, and all I was looking at was one study by Blakely et al, I’d say, “Oh, yeah, let’s vaccinate all ages”. But that’s just one piece of evidence, and it’s important that researchers like me don’t just talk, you know, about our own research. There’s a heap of other things and other considerations that policymakers should have.

Sam Hawley: Yeah, because I can see also the Australian Technical Advisory Group on Immunisation, ATAGI, which is probably an easier way to say it, also seems to agree with the W.H.O. because it’s saying Australians not at high risk should consider, but only consider, having the booster, while everyone under 18 shouldn’t have it at all. And of course everyone at high risk should have it. But it’s not saying you must go out there and get this booster shot. It’s not saying that at all.

Professor Tony Blakely: Exactly. And, you know, we’ve all had views about how ATAGI has done – I think they’ve done pretty well in the pandemic – but their kind of approach is, and this is not being critical, their approach is kind of individualistic. They’re thinking about, “how much does the individual getting vaccinated get benefit from this?”. Now, I’m not saying it’s all they think about, but there’s just a little bit of a… it’s not even a bias… it’s a little bit of a weighting that they use that way. And on that criteria alone, their logic stacks up. However, if you pull back and consider the whole of society, the population, dare I use the word the “herd”, then you do actually get that added benefit from vaccinating more people just to dampen the transmission – it provides that indirect or “shielding” type of protection for those with comorbidity. Now, is it correct? Is it ethical? Is it right for us, as public health people, and for society, to vaccinate all the younger adults to get that indirect benefit for those with co-morbidity, et cetera? That is a philosophical, if you like, or an ethical question – you can run an argument both ways.

Sam Hawley: The counter to that is, I guess, this very small risk of side effects, and the argument that young people, healthy young people don’t really need a booster, and if they have it, there is that risk of these negative side effects. Is that still the case?

Professor Tony Blakely: It’s still the case. And exactly the sort of thing ATAGI needs to think about, because when you vaccinate a population, it’s a little bit different from the patient coming into your practice as a general practitioner and saying, “I’ve got a hell of a headache, can you do something for me?”. This is us, as public health people, reaching out to the population and… not imposing… But strongly encouraging them to do something. So the ethics and the weighting of the harms and, and pros, differ a little bit. So we do need to take those considerations seriously. That all said, the risk of myocarditis is not that high, other than for teenage and young adult males. So that’s the risk that we can identify with the mRNA viruses (sic), and it’s really not that severe.

Sam Hawley: What is that? Just remind me what myocarditis is.

Professor Tony Blakely: Myocarditis – “myo” for muscle, “carditis” for heart – so it’s an inflammation of the heart tissue. Almost inevitably, it’s pretty trivial and goes away. Very seldom does it result in serious consequences, but it’s definitely a increased event that happens for people, young males in particular, also young females, but more young males, after an mRNA vaccine. It’s hardly surprising that there are few side effects and adverse effects because otherwise it’s not really doing much. It’s part of the physiological response of the body.

Sam Hawley: So there are some risks, as you note, they’re quite low. Another reason people think we should be getting vaccinated as a whole group, as the herd, as you say, is to reduce this risk of long COVID.

Professor Tony Blakely: Okay. So we’ve just talked about one of the harms. Now we’re talking about the sort of sequelae, the long-term effects of of COVID, and there’s two: there’s long COVID, there also appears to be an increased risk of those people who get infected of having heart attacks for at least a year. Right, let’s look at both of those. For both of those, the risk now is much less than it used to be. I can’t emphasise that enough. The pre-Omicron variants were more likely to induce long COVID, and when you’re vaccinated, you reduce the risk further. So, for example, the risk of long COVID for somebody infected now with Omicron, who’s been vaccinated, is probably 12.5% of what it was before Omicron if you’re unvaccinated. That is not to trivialise long COVID for those people who get it, it’s really quite unpleasant for those who’ve got it. But there’s a lot of people saying at the moment how bad long COVID is. Yes, that was true in 2020, but now it is less of a risk. It’s not zero risk, it’s a lesser risk.

Sam Hawley: Okay, that’s interesting. So, Tony, let me ask you this then, because we’re heading into winter and we know things tend to get worse when the weather gets colder. So what should we expect? I mean, will there be, do you think, a fifth wave and that wave is going to be bigger than what we’ve seen in recent times?

Professor Tony Blakely: Yep, pulling out the old crystal ball – every year we do this!

Sam Hawley: Yeah here we go. Yes, please do. Where is it? Come, have you got your bag next to you?

Professor Tony Blakely: Pulling it out now, and gazing into it! With COVID, as everybody will remember, we used to talk about our R-noughts and R-effective. That’s the number of people one person would infect, if you drop them into pre-2020, so you drop that infected person into the world in 2019 with no public health and social measures. Now we’re up to about 10 people who would get infected from that one person. That’s an R-nought of 10. That’s a lot higher than what it is for influenza – it’s somewhere around 2 or 2.5. So, for those reasons, I don’t think we are going to see COVID settling into becoming a winter-type illness for some time, if ever, because it’s got such a high R-nought. It’s just going to come and go, based on how long it takes for the population’s immunity to wane, be it from previous infection or vaccines, and whatever the new variant that comes along with its immune escape. It’s going to just keep popping up whenever it feels like popping up. And my current crystal ball says, anywhere between every three and five months, we’ll expect to see another surge.

Sam Hawley: Okay, but what about a new variant? What’s your crystal ball say saying about that?

Professor Tony Blakely: That’s highly stochastic. It’s like me looking at a rock of uranium and trying to predict which atom in there is going to be the next one to, um, to break down. I know from that rock of uranium what the average half life across all of them is, and I kind of know what the average of COVID does, but it’s impossible to say when the next variant is going to come up and whether it will be more virulent, less virulent. It will definitely have a selective advantage, so it will probably have some immune escape or something different about it that just slightly gives it an edge on the immunity we have so far, but very… impossible actually… To predict exactly what’s going to come when.

Sam Hawley: And your advice on the vaccines is: you may as well get the booster? We’re protecting society as a whole, we’re protecting the herd?

Professor Tony Blakely: Yes, but I wouldn’t be saying to people less than 60 who are fit and healthy, “you must go out and get vaccinated”. I think that becomes more of a personal choice. But part of that personal choice, part of that personal decision-making, is that individual thinking about not only their own benefit, but the benefit they provide to the herd. And people, different people, have a different response to that.

Sam Hawley: Tony Blakely is an epidemiologist and public health medicine specialist at the University of Melbourne. He’s also the chair of the Royal Commission into the COVID Response in New Zealand, and performs contract work for Moderna. In the US, the federal regulator has authorised a second booster shot for people over 65 or who have a weak immune system, while in the UK it will be offered to those over 75. This episode was produced by Flint Duxfield, Veronica Apap, Chris Dengate and Sam Dunn, who also did the mix. Our supervising producer is Stephen Smiley. Over the weekend, Catch This Week with David Lipson. I’m Sam Hawley. ABC News Daily will be back again on Monday. Thanks for listening.