番茄社区

In part 2 of this Instagram Live discussion, 番茄社区 editor-in-chief Jeremy Faust, MD, Katelyn Jetelina, PhD, MPH, and Katrine Wallace, PhD, talk about the science and anxiety surrounding a potential H5N1, or avian flu, pandemic.

Jetelina is the author of "Your Local Epidemiologist" newsletter. Wallace is with the School of Public Health at the University of Illinois at Chicago.

Watch part 1 of this interview here, where they discuss the recent rise in measles cases in the U.S.

The following is a transcript of their remarks:

Faust: I do want to move on to threat number two, H5N1 -- bird flu, avian influenza.

Just to let everyone know if they haven't gone to virology camp, seasonal flu is one thing. Year to year, there can be changes in the genetic code -- that's called antigenic drift -- but then if you have a complete swap out of a big, huge chunk of the genetic material, that's called shift.

And that usually happens and that does happen when you combine maybe one part of a flu from a bird with maybe a human flu virus, and they intermingle and out comes a new version of this virus, which we don't have any sort of immune memory to. And so H5N1 could be one of these highly pathogenic avian influenzas. That's the setup.

Again, I'll start with Dr. Wallace. What do we know about this virus, this H5N1?

Wallace: Obviously people have probably heard that we've had some human cases, all of which have been people that work directly with either poultry or dairy cattle. So there hasn't been any person-to-person spread of this virus. It doesn't seem like it's very good at spreading between people. It hasn't achieved the kind of mutations it would need to do that, so that's good.

But what I find to be a little surprising is that we're not doing a whole lot of surveillance on cattle unless they're being moved across state lines, which is the law, but we're not really doing a whole lot of active surveillance here. There's been some testing of people, but I think only like 60 people have been tested for it or something like that.

So it makes me a little bit nervous that we don't have a handle, really, on the numbers that we would need to have.

Everybody's worried that it might become like the next pandemic, and you keep seeing headlines like that. I don't think that this virus, on its own, will probably become that.

I could be wrong obviously, but what worries me is, like you're saying, one of these shift situations where a person who's working in one of these farms who has influenza already gets a co-infection with this H5N1 and then has some kind of recombinant virus that can then lead to it being more transmissible in humans.

That's what worries me about it. That's why I feel like we need to be doing a little bit more surveillance to make sure that doesn't happen.

Faust: You said that very clearly, but just to repeat something and add to it -- the way that these major pandemic-potential bugs emerge in flu is just as you said, a co-infection, so that something that's spreading through humans but is causing a normal amount of influenza disease -- which is not a good thing, but nor is it a 1918 situation -- but it's spreading in the way we would see in December and January. Imagine combining that degree of spread with the ability to cause disease that is on a 1918 level or a COVID level, and now you've got a problem.

What's interesting is, as you said, we're not seeing a human-to-human spread, but shots on goal, right? I mean, if this happens during flu season, a co-infection with a highly contagious but otherwise run of the mill flu, it could be a real shit show. I don't usually swear on these things, but I just feel like that's what we're dealing with here.

Dr. Jetelina, you are plugged into a lot of organizations and healthcare leaders that are watching this. What's the mood on the inside?

Jetelina: What's the mood on the inside? I think it depends who you ask. I think there are really two big camps here. One, that they don't believe that this is going to turn into a pandemic. And the other, that is "Let's prepare for the worst and hope for the best."

I think I'm more in the camp of "Let's prepare for the worst and hope for the best." The probability of this turning into a massive pandemic is small, like about 2% to 5% --

Faust: But that sounds big to me! That sounds huge!

Jetelina: But if we catch it, we have some huge implications to that, right? Especially since we think H5N1 is more deadly than COVID-19 or even seasonal flu that we see.

I think there's also a lot of frustration. Just like Dr. Wallace said, we feel like we can be doing more, we should be doing more. The really huge challenge with H5N1 is you have other groups, because this is a one health problem, it has animals and has humans and has a virus. So you have to get all these people talking on the same level.

The challenge is that they have different priorities. They have different legal authority, they have conflicts of interest -- it's election year, and a lot of these outbreaks are happening in swing states. I mean, it's really hard to watch, especially coming off the heels of a COVID pandemic.

So I don't know, I guess we'll see what happens. I am concerned about fall, I'm concerned about these mixing vessels that you guys are talking about. We know that pigs are mixing vessels, but we haven't seen H5 in pigs yet. We don't know if cows are mixing vessels, they certainly could be, because they have both receptors to bird and human. And then there's of course just humans working very closely to cows that could have influenza at the same time they go to work and you get a mixing vessel.

So I don't know how to answer that question other than, there's a lot of mixed feelings right now.

Faust: We had a question just now in the chat from Dr. Marcio Nehab about how long does it take to produce a big amount of vaccines for bird flu? And I think that's a great question to tackle.

First of all, I want to preface this by saying that one of the things that went well in the COVID experience was Operation Warp Speed. That was our effort to get a vaccine out, and there were a couple of things that made that work.

One was to sort of combine phase one and phase two and to get phase three going really quickly.

Another thing that helped -- which was not even a matter of the policy of Operation Warp Speed, but just the situation -- was that a lot of times vaccine trials take a long time because you don't have enough cases. Unfortunately, in the COVID experience, we had plenty of cases, right? So we got data. We usually would've expected it would take 10 years to get as many cases for a pathogen that we're interested in preventing. It took a few months.

But the third thing that was so important that gets to this question is that the companies got permission to start making the vaccine before we knew it worked. Meaning [the companies] were going to be made whole, the government was going to pay Moderna, in our case, and then Pfizer. Even if it didn't work, they were going to get paid for that stuff. That way if it did work, we didn't have to build up and spend months and months producing this stuff.

Do we have any idea of how long it would take to get 10,000 doses of a new vaccine, and then a million, and then a hundred million?

Wallace: What I do know is that Moderna has entered into the same type of deal with the NIH to develop a bird flu vaccine here in the U.S. So that's at least being worked on, it's already underway. And I guess they're trying to do it pretty quickly because flu season is coming up.

Faust: I'd forgotten about that. $176 million, right? It's funny how many news cycles ago that was. I forgot! I know. But I actually don't know, and maybe you don't either, whether that money is purely "Just go make the stuff and test it," or is part of that "If it works, make us a couple million doses, then if that works, do that a hundred times."

Wallace: I don't know.

Faust: Yeah. But I think that Warp Speed showed that principle at work, which is that we could get it done in 100 or 150 days.

Jetelina: Yeah. I'll add to that we already are manufacturing vaccines. We'll have 5 million ready in August. Those aren't mRNA vaccines, they're your traditional types of vaccines, but that's a really big difference from COVID is that we're not starting from zero. We actually know a whole lot about H5N1. In fact, we know exactly where it needs to mutate so we start seeing human-to-human transmission. So I think that we're already ahead.

The other thing that we have in place is we already have a massive system in place to manufacture and distribute flu vaccines. So we just need to figure out what's that "oh shit" line where we start integrating it into our full flu vaccine pipeline. That gives me a little hope.

The challenge is that like we just saw with COVID-19, vaccines aren't everything. It's not going to fix it. We actually don't know how well a H5N1 vaccine would work once it mutates to humans. We don't know how much prior immunity to flu will help. We have a lot of unanswered questions.

And so, I urge people not to just say, "Hey, we will have a vaccine. We'll be fine." Because it can turn into quite a disaster quickly.

Faust: There's a good question someone here has. Dr. Jetelina, when you say a 2% to 5% chance of becoming a pandemic, what's the timeframe of that over the next year or the next 20 years?

Jetelina: Every year. So every year we have about a 2% chance of any pandemic hitting. Now, with H5 and it's spreading in cows and we're close to cows and humans are getting infected, that increases the probability a little. So that's why I say 5% to 7%. I haven't done the math, but that's just my back of the napkin guess.

Faust: Right. It's funny you mentioned like the two moods, when people are more hopeful or more measured. But it seems to me like the cautionary principle is often invoked in a weird way that means alarmism. I think this is a good example of the precautionary principle being important.

Like you and me, we don't have to act like there's bird flu in our neighborhood right now, but there are farmers and surveillance workers who do. And so I think the action items aren't for the average person right now. The action items are for public health officials and people working in the cattle and bird space.

Jetelina: Right. And I actually think that's a really important distinction that leaders aren't really making that much clearer. Because there's a time when epidemiologists and virologists freak out, right? That's kind of now. We're like, "This is not great. Red flag, red flag," but that doesn't translate to "red flag, red flag" to the general public because there's no action for them to do. And the problem coming off the heels of COVID is that red flag for epidemiologists was directly translated to red flag for the general public.

But this is a very different situation right now, and I think we could do better communicating that disconnect so people don't feel fear or anxiousness or hopelessness. Because literally, their risk is low and there's nothing that they can do unless they're working on farms.

Faust: Right. And I think that the risk is low thing, that's very much a today thing. That's like the weather forecast. The risk of rain today is low here, but the risk of rain next month is high.

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