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  • Thanks to Brilliant for supporting this episode of SciShow.

  • Go to Brilliant.org/SciShow to learn how you can take your STEM skills to the next level!

  • [♪ INTRO]

  • This episode was shot on May 5th 2020.

  • If we have any updates about COVID vaccines or on the pandemic in general,

  • you will find links in the description.

  • Right now, experts say a vaccine for COVID-19 is a year or more away.

  • Which might seem like forever.

  • But that's actually ridiculously fast, considering the usual process takes upwards of a decade.

  • And it's only within the realm of possibility because

  • vaccine development is being accelerated on an unprecedented scale.

  • And there are several ways this is happening.

  • But, it's important to remember that nothing done at breakneck speed comes without costs.

  • So let's talk a bit about what's being tried and the cost-benefit math

  • researchers and governments are doing to get a vaccine out as soon as possible.

  • Here in the US, as of the end of April 2020,

  • two vaccine candidates had begun human clinical trials.

  • And, notably, they share something in common.

  • They're what are called nucleic acid vaccines

  • because they immunize a person using either DNA or RNA.

  • The overall aim of any vaccine is to safely expose your immune system

  • to the important bits of a pathogen, called antigens.

  • Those are what the vaccine trains your immune system to spot,

  • so it's better equipped to fight off a disease in the future.

  • And old school vaccines deliver these antigens directly,

  • like by injecting a weakened or killed version of the virus.

  • DNA- and RNA-based vaccines do something a little different.

  • Much like actual viruses, they reprogram cells to make the antigen on their own.

  • And if that doesn't sound futuristic enough all by itself,

  • this technology is also the quickest way

  • to make a vaccine for a new virus, for two main reasons:

  • First, these vaccines are essentially plug and play.

  • Once you've figured out the system you're using to deliver the DNA or RNA

  • into a person's cells, you can make one for any antigen, pretty much right away.

  • And second, unlike with traditional vaccines, you don't need a sample of the virus.

  • Scientists can grab the genetic sequence for the antigen they want

  • off a website and start churning out their new vaccine candidate.

  • That's why literally three hours after Chinese researchers

  • uploaded the genome of the new coronavirus,

  • Inovio Pharmaceuticals had already designed their DNA vaccine.

  • Overall, nucleic acid vaccines are considered very promising.

  • But they're still new and experimental.

  • While a few of them have been approved for veterinary use,

  • there isn't a single one on the market for humans.

  • So, though they were first out of the gate, we don't really know if they're going to work.

  • In fact, there's a lot we don't know, because changing up the type of vaccine

  • isn't the only way scientists are speeding up the development process.

  • Some are essentially jumping the gun

  • and starting human trials before animal studies are complete.

  • Normally, potential vaccines undergo what's called preclinical testing:

  • you try them out in cell cultures and animal models before sticking them into a person.

  • But some teams are skipping ahead to clinical trials before that testing is complete.

  • For example, the biotech research company Moderna and their partner,

  • the US National Institutes of Health, didn't wait to see what happened in animals

  • before starting clinical trials for their RNA vaccine.

  • Their first human subject was dosed a record 63 days after the virus's genome was released.

  • Now, this isn't necessarily as risky as it sounds.

  • Remember what I said about these vaccines being plug and play?

  • Well, scientists have tried out all of these same systems in people before,

  • so they know that all of the bits involved in

  • delivering the DNA or RNA into people aren't harmful.

  • And researchers learned a lot while working on

  • vaccine candidates for the related SARS and MERS;

  • insights which make the human trials safer and more predictable,

  • even before they have the animal study results in hand.

  • Problem is, that research also revealed something kind of unsettling

  • about coronaviruses specifically: sometimes, vaccines for these viruses backfire.

  • Instead of conferring protection, they can help the virus;

  • a rare reaction called antibody-dependent enhancement.

  • Studies are inconclusive on how exactly this happens, but it seems like antibodies

  • essentially create a backdoor into cells and hand the invader the key to it.

  • We don't know if this is going to be an issue with this new coronavirus or not,

  • but the possibility does make jumping ahead past animal trials a bit riskier.

  • Though, it's not the riskiest way to fast-track a COVID vaccine.

  • Some are proposing that promising vaccines be

  • sped through the development process by using human challenge studies.

  • That's pretty much what it sounds like;

  • to see if the vaccine really works, you infect people with the virus on purpose.

  • Now, normally, you try to get this information indirectly

  • using a huge clinical trial with thousands of participants over a fairly long time.

  • The idea being that if thousands of people receive the vaccine, eventually

  • some of them will get exposed to the virus while just going about their daily lives.

  • So, if you wait long enough, like, over a year,

  • you'll be able to see whether the vaccine works.

  • With a human challenge study, there's not really any waiting,

  • other than the few weeks it takes to make sure the vaccine has done its thing.

  • And not only does this cut down the total trial duration to a few months,

  • because you know who's been exposed to the virus,

  • these studies require only about a hundred volunteers.

  • The idea may seem surprising, but human challenge studies

  • have been used for decades to research vaccines and medications

  • for diseases like the flu, dengue fever, and tuberculosis.

  • But for COVID-19, even if volunteers are carefully selected,

  • there are still some huge ethical questions.

  • That's because we're dealing with a new illness that we don't completely understand,

  • and that we don't have any proven treatments for.

  • So there's no way to prevent the worst-case scenario.

  • Whatever the approach, accelerating the time-tested vaccine approval process

  • may seem like a huge, ethically-questionable gamble.

  • And, in some ways, it is. Scientists have been very up front about that.

  • They've said that the kinds of things being done now to rush this vaccine

  • would be unthinkable, were it not for the fact that the pandemic is a global emergency,

  • and every day we shave off that year-or-more-timeline may save lives.

  • Plus, even if some of the COVID-19 vaccine candidates hopscotch the usual vaccine trial steps,

  • it's unlikely that any vaccine will be distributed to the general population

  • before we are completely sure about its safety.

  • We here at SciShow are not qualified to tell you what to think about this;

  • the most we can say is that these are very hard, complicated decisions.

  • But one thing is certain: all over the world, thousands of brave volunteers

  • are signing up for these accelerated vaccine trials,

  • and we owe all of them a huge debt of gratitude.

  • Speaking of gratitude, I would also like to thank our sponsor for this episode: Brilliant.

  • Brilliant offers dozens of courses in STEM topics,

  • all of which are engaging, interactive, and fun.

  • So they've got something for everything, whether you're looking to brush up on the basics

  • or want to go in depth to understand the world around you better.

  • For instance, their Calculus in a Nutshell course gives you an overview

  • of how this branch of mathematics is essential for everything from ecology to economics.

  • And, as a thank you for being a SciShow viewer,

  • the first 200 people to sign up for an annual premium subscription

  • at Brilliant.org/SciShow will get 20% off! You can head on over there now to learn more.

  • [♪ OUTRO]

Thanks to Brilliant for supporting this episode of SciShow.

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