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  • - [Daniela] In response to the coronavirus crisis,

  • researchers are working at a breakneck pace

  • to develop solutions that will allow economies

  • to reopen safely and permanently.

  • - Without an effective vaccine,

  • we won't be able to get this pandemic under control

  • and stop the devastation that it's currently causing

  • all around the globe.

  • - Vaccines can take an average

  • of 10 years to develop, according to a 2013 study,

  • but researchers and pharmaceutical companies

  • are hoping to bring their vaccine candidates

  • for the new coronavirus to market in 12 to 18 months.

  • Some are even talking about getting

  • Emergency Use Authorizations before the end of the year.

  • So what is making it possible

  • to expedite this process so dramatically?

  • There are several factors,

  • including prior knowledge of coronaviruses,

  • specifically SARS and MERS,

  • improvements in sequencing of viral genomes,

  • advancements in bioengineering technologies,

  • unprecedented government support and funding,

  • plus a shortened testing timeline.

  • Traditionally, after scientists develop a vaccine candidate,

  • they run it through a series of tests.

  • This starts in cells, and then transitions to animals,

  • usually beginning with mice

  • and eventually progressing to monkeys.

  • Testing only advances from one phase to the next

  • if it's proven to be safe and effective.

  • - At that stage, you would then likely perform

  • what we call a challenge study,

  • so that would be vaccinating an animal

  • then intentionally giving them the virus

  • and seeing the impact of your vaccine on that disease model

  • where, of course, you would hope to protect it.

  • - Then they'd use that data to get approval from regulators

  • like the FDA to begin human testing.

  • There are three stages of human trials,

  • each one testing more people than the last.

  • Approval is required for each stage.

  • Instead of this relay approach

  • where researchers wrap up each set of experiments

  • before embarking on the next round,

  • developers are now doing many tests in parallel.

  • - So we're not skipping steps, but we're doing things

  • at the same time, which of course costs a lot more

  • and is a lot more work than doing it one after the other,

  • and that's the key difference.

  • - The novel coronavirus was discovered and sequenced

  • less than six months ago.

  • Several candidates are already in phase one of human trials,

  • including those made by Inovio and Pfizer,

  • even as companies await results from animal studies.

  • Moderna recently started phase two.

  • Others are gearing up for phase two

  • before phase one wraps up.

  • - Our phase one trial will run for a year,

  • but we're not going to wait for that full year period

  • to have elapsed before we hopefully move on

  • to the next stage of efficacy testing.

  • - Because of the worry of COVID-19 being so devastating,

  • we are expediting those processes,

  • and this oughta concern, because we don't really know

  • all that much about immunity to this virus,

  • that we may be going too quickly,

  • but so that's the balance here.

  • - [Daniela] Vaccines work on a simple premise.

  • They trick the body into thinking a virus has infiltrated it

  • so the immune system kicks into action

  • and starts producing antibodies and other defenses

  • against parts of the virus.

  • In this case, scientists think their target

  • is the spike protein, which the coronavirus uses

  • to get into cells.

  • - It's been shown from SARS and MERS

  • that the spike protein is the major protein

  • on the outside of the virus of these coronaviruses

  • to which erase neutralizing antibodies,

  • and neutralizing antibodies is what you need

  • to fight the infection.

  • - So what would really end the pandemic

  • is when there's enough immunity in the population,

  • and either than immunity

  • comes from everybody getting infected

  • or it comes from a vaccine,

  • and it's a much gentler path for everybody to get a vaccine

  • than for everybody to get infected.

  • - [Daniela] This concept is known as herd immunity.

  • Dozens of companies and labs are trying various technologies

  • to develop vaccines that would get us there quickly.

  • Scientists say it's the largest,

  • most collaborative vaccine development effort

  • they've seen in their lifetimes.

  • They're testing four main strategies,

  • weakened viruses, proteins,

  • viral vectors, and genetic code vaccines.

  • Weakened or inactivated virus vaccines

  • are the most common.

  • That's your annual flu shot.

  • We have the most experience with these,

  • but they can also be costly

  • and time-consuming to mass-produce,

  • so in this case, they haven't been the preferred approach.

  • Protein-based vaccines

  • carry key parts of the virus into the body.

  • For coronavirus, that's the spike protein.

  • Sanofi and GlaxoSmithKline

  • are among dozens of developers taking this approach.

  • For viral vector vaccines,

  • scientists use an inactivated virus and stuff it

  • with the genetic code for the spike protein,

  • which our cells then use to turn out viral proteins.

  • The immune system then recognizes those as foreign.

  • Johnson & Johnson is developing this type of vaccine

  • for the coronavirus.

  • - [Gert] We use adenovirus vector,

  • and this adenovirus is a common cold virus

  • which normally doesn't cause any major disease,

  • just a common cold.

  • In the adenovirus, it becomes replication incompetent.

  • - [Daniela] In the fourth and final category

  • are genetic code vaccines.

  • These contain the instructions for the spike protein.

  • COVID vaccines being developed by Inovio,

  • Pfizer, and Moderna fall into this category.

  • These types of vaccines have never been approved

  • for humans before,

  • but they're generating a lot of excitement.

  • - The reason we're seeing them out in front is the speed.

  • - The speed in the manufacturing and the development?

  • - Yeah, really, both.

  • Proteins are more diverse.

  • They have all kinds of different shapes

  • and characteristics and so you have to play with a lot more

  • to actually get a protein-based vaccine made.

  • - [Daniela] Pfizer is running multiple candidates

  • through phase one trials in the U.S. and Germany

  • to cut down on development time.

  • - And even before we know whether the vaccine works or not,

  • we're starting to ramp up manufacturing capacity

  • so that we're ready to make it right away.

  • The key things you have to establish to develop a vaccine

  • are that it is safe, that it's effective,

  • and that every time you make it, it comes out the same,

  • so those key steps don't change whether you're going fast

  • or you're going slow.

  • - Changes in manufacturing can introduce unforeseen issues

  • that could make a vaccine dangerous.

  • That's what happened with the since-discontinued

  • polio vaccine decades ago.

  • Safety is a major concern,

  • because vaccines are given to healthy people,

  • so scientists have to ensure they don't affect things

  • like liver or heart function among other factors.

  • There are other issues as well.

  • Even if companies are able to come up with a vaccine

  • in less than two years, the vaccine research community

  • is concerned with how they'd be able

  • to produce and distribute it to everybody on the planet.

  • - So we are aiming to produce one billion dose

  • by the end of 2021, and some other companies

  • are committing to the same kind of scale,

  • either hundreds of millions or billions,

  • but still, it will not be enough for everyone.

  • - What is a big unknown is what the durability

  • of that protection is.

  • Is it going to be a year, two years,

  • or even maybe, unfortunately, six months or less,

  • because if it is measured in several months

  • instead of years, which is entirely conceivable

  • that that would be the case,

  • then we have a secondary problem.

  • How often do you need to boost somebody

  • to keep that level of immunity up?

  • - [Daniela] The final and perhaps most important hurdle

  • for coronavirus vaccine development will be human behavior.

  • - Are people gonna be accepting of this vaccine?

  • That's been such a huge problem in this country.

  • You know, if you have 50% of people

  • saying I'm not gonna take it under any condition,

  • then, of course, you've lost the whole battle.

- [Daniela] In response to the coronavirus crisis,

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The Promise and Peril of Fast-Tracking the Coronavirus Vaccine | WSJ

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    joey joey に公開 2021 年 05 月 30 日
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