Lab Notes: Are we on the brink of another pandemic?
13:24 Share

A strain of avian influenza is currently ripping through the US, infecting wildlife, livestock and people. The first American to contract a severe case of bird flu has died in Louisiana. There are now 70 confirmed cases in humans, but the real number of infections is likely to be much higher.

The latest from the US Centers for Disease Control and Prevention is: The risk level right now to public health is actually low. But this comes as the Trump administration makes massive cuts to the nation's leading health agencies. So does this mean we're on the cusp of another pandemic? Hi, I'm Belinda Smith and this is Lab Notes, the show that dissects the science behind new discoveries and current events.

Today, we find out how the US got into this situation and what it means for pandemic preparedness, not just in the States, but also around the world. Joining us is Professor Raina McIntyre, head of the Biosecurity Program at the Kirby Institute, a medical research organisation in Sydney.

Now, bird flu has been making dozens of people sick in the US and in January this year, the first person died from the disease. So what's the current situation now? It's very serious in that, you know, really since 2020, there's been this unprecedented increase in

This one particular strain of bird flu, H5N1, a new variant of it, if you like, emerged around 2020 and then just started to spread further and wider across the world, infecting far more species of wild birds than had ever historically been infected and also starting to infect mammals and other animals across the world. And together with that, we saw a shift from the historical trend

epicenter of bird flu, which used to be in Asia and now has moved to the Americas and Europe. So we've had really unrelenting epidemics. Normally, the pattern has been that you get an outbreak and then it dies down and then it goes away for a while and then you might have another outbreak

But this H5N1 outbreak just won't quit. And it's been in poultry farms in the US since 2022. So how did it get into dairy farms? We've done some research showing that likely the first incursion into the US early last year was through a wild bird into a farm. Once it was in the farms, it spread farm to farm and back and forth between birds to animals, animals to birds. The

The most recent figures suggest that nearly 1,000 dairy herds across 17 US states have since been infected with H5N1. The whole milking process has acted like a super spreader event. So we now have a situation in the US particularly where it is not just in wild birds and farmed poultry but in farmed animals as well. And not just dairy cows, it's been affecting goats as well.

alpacas and other farmed animals. And it's close contact with infected farm animals which has mostly led to infected people. Humans have a particular kind of receptor in their upper respiratory tract, so in the nose and throat, that binds human seasonal flu. So the seasonal flu virus will come in and it'll bind into receptors in our nose and throat and then invade the body and cause illness.

Birds have a different kind of receptor that humans do not have abundantly in their respiratory tract. That is why avian flu doesn't spread easily between humans. But that might change. Flu viruses switch up their genetic code, like, a lot. It's why we need a new flu shot each year.

And there's a lot of flu flying around. The Centers for Disease Control says this flu season is the worst the US has seen in 15 years. What we worry about is that when a human being with human influenza has close contact with an animal or a bird with bird flu, that the two viruses can exchange genetic segments and reassort to generate a human pandemic virus.

Now, that's not happened yet. But if this genetic exchange between flu viruses did happen, it'd probably happen in a pig. Pigs have both the receptors that humans have and birds have. This means a worker on a pig farm could pass the human flu to a pig and a wild duck might fly in and also give that same pig the H5N1 bird flu.

So the pig is the ideal genetic mixing vessel to allow that mutation to happen. And last October in Oregon, US agriculture officials have found the first ever case of bird flu in a pig, along with 70 birds. The Crook County farm where they lived is not commercial though, so the animals weren't part of the public food supply. So what we worry about is the avian virus adapting and mutating to

to pick up genetic characteristics from the human virus that allows it to bind easily to the human respiratory tract. And when that happens, you've got the conditions for a pandemic. Just to clear up any confusion, the bird flu that's recently been found in poultry farms in Australia, particularly Victoria, that's the H7N8 virus.

The H5N1 virus, which is currently infecting humans in the US, that's not been detected in Australia yet. We're the only continent without it. Now, this spread of a respiratory disease between animals and humans all sounds eerily familiar to COVID. So how similar are the viruses? Similar in that they're both respiratory viruses that have pandemic potential. And the potential to cause a pandemic, what we call a pandemic, is really...

a virus that humans haven't experienced before, which makes us very susceptible because our immune systems are not primed to meet this virus. That's why you get really severe illness when it first hits. So the seasonal flu viruses that we see every year, once upon a time, they were pandemic viruses.

but they've been circulating for so long in human populations that we have immunological memory to them and we don't get as sick as we would have back in the 1918 pandemic. Look, it may be too early to say this, but since we've seen one fatality in the US to this H5 strain of bird flu...

Do we know how serious this illness might be? H5N1 has been affecting humans since 1997 and all the data from H5N1 up to this epidemic in the US suggested about a 50% case fatality rate. However, it's been a lot less. About 70 human beings in the US have had it and it's been largely mild. Most of those 70 people in the US had a variant of H5N1 called PN1

B3.13. I know, not the greatest name, but we've got to work with it. The person who died in the US, as well as a teenager in Canada who was put on life support, they were infected with a different variant called D1.1.

Luckily, it's just those two really severe D1.1 human cases so far, most are B3.13. Some variants of this virus, including one found in eagles in the US, is it invades the brain. So one of the clinical presentations I might expect or be looking for in a human pandemic is neurological. You might also see encephalitis, seizures, you know, cerebral effects of the virus.

Is there a vaccine for bird flu for humans? There is. There are what's called pre-pandemic vaccines, which is where they make vaccines that are matched to what they think is the most likely H5 variant. So it's matched to the H5. And some countries like Finland, they've started vaccinating people at high risk. Oh, wow. It sort of feels like we have a jump here.

On the situation compared to early 2020, I'm not saying that bird flu will definitely become a pandemic disease, but...

you know, is this kind of like a good place to be in that we've got potential vaccines? No, it's not a good place to be in at all. But having said that, if it's flu, we are better prepared than any other virus because flu has always been the focus of pandemic planning. And we are very experienced at making flu vaccines. We've got numerous flu vaccine manufacturers. We've got manufacturing capacity in Australia. We've now got mRNA capability as well in Australia.

This means we could turn around mRNA vaccines relatively quickly, like in six weeks or so. But whether people are willing to get vaccinated is a whole separate issue. We are going to face an uphill battle because I think the COVID pandemic has seen a massive rise in disinformation and anti-vaccine sentiment, anti-science sentiment. We're going to see a lot more

societal resistance to vaccines and public health measures in general if there was another pandemic. That's a more important barrier, I think, than the science of making the vaccines. And that's particularly relevant now that Robert F Kennedy Jr., a well-known anti-vaxxer, is head of Health and Human Services. We've also seen the Trump government tell the CDC to stop publishing some of its data. What does that mean for other countries?

I think the world has relied on the US for a very long time. They've had really good data on their CDC website and they've obviously funded global health in many different organisations and countries more than anyone else. So I think, you know, the role of

independent and resilient health intelligence is going to increase, where we may not be able to rely on governments or on NGOs like WHO to provide us what we need. I mean, after the US announced they were leaving WHO, a handful of other countries have also signalled their interest in leaving WHO. So we could see a sort of domino effect.

What about Australia? So, you know, does this change how we would get ready for the next pandemic? I don't know. I think Australia also is at a bit of a crossroads. I think there's some work that Australia needs to do around our national identity and who we are and what's in the best interests of our country.

But there's a lot we can do as a nation to protect our own interests and we should be doing that. And that includes, you know, ensuring that there is a commitment to adequately fund the CDC in Australia and to make sure that it is sustainable and can withstand changes in government. What are you most worried about with this bird flu thing going on in the US? I think of everything in terms of statistical probabilities.

And the statistical probability of that mutation occurring because the human-type virus and the bird-type virus have opportunities to mix together, there's enormous opportunities, not just through the farmed animals and humans working on farms and the poultry. It's in the food chain. If you check the milk on the supermarket shelves in the U.S.,

about 30%, sometimes higher, sometimes a bit lower, depending on what studies you look at, are positive for H5N1. Now, pasteurization would generally kill the virus, so you wouldn't expect to get infected even if the milk is contaminated. But there is a huge market for raw milk in the US. So people who are drinking raw milk, absolutely, it's a risk. Whether or not it's in the beef, who knows, you know? So it's in the food chain. And

there's just greater opportunities for that event to happen. As individuals, is there anything kind of we can do? Getting out and getting vaccinated. So if you have your seasonal flu vaccine...

You're probably better off than not having been vaccinated at all. And we're coming up, you know, in March, April to the time when the seasonal flu vaccines will be available. We've just seen a very, very severe flu season in the US. It's still ongoing. We've seen young, healthy teenagers and children dying of the flu in the US. If that's any sign of what's ahead for us, it's really worth getting vaccinated. Professor Raina McIntyre, Head of the Biosecurity Program at the Kirby Institute.

Thanks for listening to Lab Notes, where every week we bring you the science behind new discoveries and current events. I'm Belinda Smith. This episode was produced on the lands of the Wurundjeri and Menang Noongar people. The show was produced by Fiona Pepper and mixed by Tim Simons. And if you've got topics you'd like us to cover, send us an email, labnotes at abc.net.au. I'll catch you next week.