WEBVTT - Why Is a Universal Flu Vaccine So Difficult to Develop?

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<v Speaker 1>Welcome to brain Stuff, a production of iHeart Radio, Hey

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<v Speaker 1>brain Stuff, Lauren vogelbam here. Your annual flu shot protects

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<v Speaker 1>you from some types of influenza, usually the ones that

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<v Speaker 1>got people sick the year before, but if a new

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<v Speaker 1>strain of flu shows up, the shot may not work

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<v Speaker 1>for it. That's why holy grail of medicine is to

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<v Speaker 1>create a universal flu vaccine, and a universal flu vaccine

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<v Speaker 1>can't come soon enough, especially for particularly vulnerable populations such

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<v Speaker 1>as children, the elderly, and the immune compromised. More than

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<v Speaker 1>six hundred and fifty thousand people around the world die

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<v Speaker 1>of seasonal influenza every year, according to the World Health Organization.

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<v Speaker 1>The seasonal flu also costs the US health care system

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<v Speaker 1>in society in general a lot, about eleven point two

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<v Speaker 1>billion dollars in eighteen alone. Of course, this is to

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<v Speaker 1>say nothing about COVID nineteen, which is caused by a coronavirus,

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<v Speaker 1>which is an hirely different virus than the multiple strains

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<v Speaker 1>of influenza that cause the flu. Although some symptoms of

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<v Speaker 1>both COVID nineteen and the flu can be similar. The

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<v Speaker 1>researchers are racing to develop the first coronavirus vaccine, though

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<v Speaker 1>none have been successful yet. These things take time. But

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<v Speaker 1>we've had vaccines for the flu for years, so why

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<v Speaker 1>haven't we developed a universal flu vaccine that could stop

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<v Speaker 1>all future iterations of the flu. The threat and impact

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<v Speaker 1>are so great that it would surely be worth researchers time.

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<v Speaker 1>It has to do with the fact that influenza is

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<v Speaker 1>incredibly cunning. We talked with Dr Greg Poland, spokesperson for

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<v Speaker 1>the Infectious Diseases Society of America and professor of Medicine

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<v Speaker 1>and Infectious Diseases at the Mayo Clinic in Rochester, Minnesota.

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<v Speaker 1>He noted the trillions of new strains of the flu

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<v Speaker 1>can develop in mere minutes. Quote, you can hardly imagine

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<v Speaker 1>a more promiscuous virus. Fortunately, of new strains don't have

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<v Speaker 1>genetic fitness us they can't survive. However, those that remain

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<v Speaker 1>can pack a pretty serious punch. Those survivors can either

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<v Speaker 1>experience antigenic shift or antigenic drift. Let's break that down.

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<v Speaker 1>In antigenic shift, a gnome strain of the flu morphs

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<v Speaker 1>into a novel strain that can cause a pandemic level

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<v Speaker 1>flu event, such as H one, N one and avian influenza.

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<v Speaker 1>This hardly ever happens. There have been just four influenza

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<v Speaker 1>pandemics in the last hundred years, but when it does,

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<v Speaker 1>it can be dire. The shift that resulted in the

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<v Speaker 1>H one N one influenza pandemic of en sometimes called

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<v Speaker 1>the Spanish flu, infected five hundred million people and killed

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<v Speaker 1>fifty million around the world. This was, of course, before

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<v Speaker 1>antibiotics were available to treat secondary bacterial infections associated with

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<v Speaker 1>the flu. Also, vaccines were not around to prevent infection

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<v Speaker 1>and lesson severity. But back to shift and drift. In

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<v Speaker 1>comparison to rare but dangerous shifts, antigenic drift happens all

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<v Speaker 1>the time with influenza, resulting in many small changes to

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<v Speaker 1>the virus, which makes it tricky for vaccine developers to

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<v Speaker 1>nail even the annual flu virus squarely on the head.

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<v Speaker 1>Poland said, so, what happens is about a quarter of

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<v Speaker 1>a million viruses are isolated every year and genetically sequenced

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<v Speaker 1>to give us an idea of what's circulating. It takes

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<v Speaker 1>six months or so to develop and distribute the flu vaccine.

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<v Speaker 1>By that time, many of the strains have drifted to

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<v Speaker 1>the point where they have next to no protection, meaning

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<v Speaker 1>that one of the reasons you can still get the

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<v Speaker 1>flu after receiving a flu vaccine is that the strain

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<v Speaker 1>you get may have developed after the vaccine was created. Again,

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<v Speaker 1>these things take time, but it's worth noting here that

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<v Speaker 1>even a mismatched vaccine is known to reduce the severity

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<v Speaker 1>of flu symptoms and the length of the overall illness,

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<v Speaker 1>so it's important to get the vaccine annually if you can.

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<v Speaker 1>After all, it's better to be bedridden for three days

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<v Speaker 1>than seven or worse, to end up in the hospital.

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<v Speaker 1>There are multiple roadblocks to developing a universal flu vaccine,

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<v Speaker 1>but a number of biotech companies and academics are currently

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<v Speaker 1>working to overcome them. Poland explained that one idea is

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<v Speaker 1>to develop broadly neutralizing antibodies to influenza viruses that would

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<v Speaker 1>ideally protect against every influenza strain. Let's talk a bit

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<v Speaker 1>about how the influenza virus works. Simply put, the influenza

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<v Speaker 1>virus is made up of a couple types of proteins

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<v Speaker 1>called H proteins and N proteins, plus a stock. Current

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<v Speaker 1>vaccines attempt to teach your immune system how to hit

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<v Speaker 1>the H and N proteins, which are what the virus

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<v Speaker 1>uses to attach to and infect human cells. The problem

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<v Speaker 1>is that the exact makeup of those proteins drifts all

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<v Speaker 1>the time. By comparison, Poland explained, the stock portion is

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<v Speaker 1>relatively invariant. So the very it has been why don't

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<v Speaker 1>we shift how we technologically make flu vaccines to the

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<v Speaker 1>portion of the virus that doesn't shift and drift. Another

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<v Speaker 1>complexity is that flu viruses only infect the outermost cells

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<v Speaker 1>lining the respiratory tract, a part of what's called the

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<v Speaker 1>respiratory mucosa. Flu Viruses do not replicate throughout the body,

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<v Speaker 1>which is known as systemic replication. But we also spoke

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<v Speaker 1>with Dr Jeffrey Taubenberger, a virologist with the National Institute

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<v Speaker 1>of Allergy and Infectious Diseases. He said, if you look

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<v Speaker 1>at vaccines that provide good lifelong immunity, like measles, one

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<v Speaker 1>of the differences there is the kind of recall you

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<v Speaker 1>get from a systemic infection is different and much better.

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<v Speaker 1>There's something we're not understanding about how immunity at the

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<v Speaker 1>mucosal level sets up long term immunity. This kind of

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<v Speaker 1>protective immunity is hard to establish. We have to come

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<v Speaker 1>up with ways to bolster the mucosal immune responses to

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<v Speaker 1>give us better protection with these kinds of vaccine. So,

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<v Speaker 1>in other words, a universal vaccine would again ideally help

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<v Speaker 1>your immune system at the local level where the infection

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<v Speaker 1>actually occurs, but we just don't understand enough about how

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<v Speaker 1>that works in order to help. Once this gets worked out,

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<v Speaker 1>it could prove helpful in the development of universal vaccines

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<v Speaker 1>for other respiratory ailments like coronavirus. With any luck, one

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<v Speaker 1>or more of the numerous universal flu vaccine development efforts

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<v Speaker 1>currently going on will pan out. A version developed by

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<v Speaker 1>the pharmaceutical company Seek is about to enter phase three

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<v Speaker 1>clinical trials, and Dr Taubenberger's own team is hoping to

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<v Speaker 1>start human clinical trials on their vaccine in and don't

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<v Speaker 1>expect a universal flu vaccine to be ready too soon, though,

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<v Speaker 1>as it's an arduous undertaking that requires a lot of

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<v Speaker 1>trials to get FDA approval. It's a multi step process

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<v Speaker 1>that ensures that drugs are safe and effective. Poland explained.

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<v Speaker 1>Typically it takes hen or more years and it costs

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<v Speaker 1>about a billion dollars. We should note that in case

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<v Speaker 1>of emergency, new drugs can and have been brought through

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<v Speaker 1>the process sooner, but it takes again, work and money.

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<v Speaker 1>Today's episode was written by Aliya Hoyt and produced by

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<v Speaker 1>Tyler Clang. For more in this and lots of other topics,

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<v Speaker 1>visit how stuff works dot com. Brain Stuff is production

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