Previous: From Old-School Gardening to the Future of Food.
Next: Does Hand Sanitizer Create Superbugs?



View count:5,390
Last sync:2020-05-08 17:30
Go to to try their Calculus in a Nutshell course. The first 200 subscribers get 20% off an annual Premium subscription.

Right now, experts say a vaccine for COVID-19 is a year or more away. But as far away as it sounds, it’s only within the realm of possibility because scientists are speeding up the vaccine development process in surprising ways.

COVID-19 News & Updates:

Hosted by: Hank Green

SciShow has a spinoff podcast! It's called SciShow Tangents. Check it out at
Support SciShow by becoming a patron on Patreon:
Huge thanks go to the following Patreon supporters for helping us keep SciShow free for everyone forever:

Kevin Bealer, Jacob, Katie Marie Magnone, D.A. Noe, Charles Southerland, Eric Jensen, Christopher R Boucher, Alex Hackman, Matt Curls, Adam Brainard, Scott Satovsky Jr, Sam Buck, Ron Kakar, Chris Peters, Kevin Carpentier, Patrick D. Ashmore, Piya Shedden, Sam Lutfi, Charles George, Christoph Schwanke, Greg

Looking for SciShow elsewhere on the internet?
Thanks to Brilliant for supporting this episode of SciShow.

Go to 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 will get 20% off! You can head on over there now to learn more. [♪ OUTRO].