Speaker 1: Welcome to Prognosis. I'm Laura Carlson. It's day one and
Speaker 1: eighty nine since coronavirus was declared a global pandemic. Today's
Speaker 1: main story. The more we learn about the virus, the
Speaker 1: more ways we have to shift our behavior. The latest surprise,
Speaker 1: how loud we speak may matter for limiting the spread
Speaker 1: of the virus. But first, here's what happened in virus
Speaker 1: news today. Top US health officials offered conflicting estimates of
Speaker 1: when Americans should expect a widely available coronavirus vaccine. In
Speaker 1: an interview today, Paul Mango, Deputy Chief of Staff for
Speaker 1: Policy at the Department of Health and Human Surfaces, offered
Speaker 1: a very ambitious timetable. He said every American could be
Speaker 1: able to get a shot by the end of March.
Speaker 1: His remarks came after President Donald Trump set in a
Speaker 1: televised town hall event last night that a vaccine could
Speaker 1: be approved in three or four weeks. But the director
Speaker 1: of the Centers for Disease Control and Prevention, Robert Redfield,
Speaker 1: gave Senate testimony today and he was less optimistic than
Speaker 1: Mango or Trump. His estimate was that most Americans wouldn't
Speaker 1: be able to get a shot of an effective vaccine
Speaker 1: until the second or third quarter of next year. Astra
Speaker 1: Zenica's vaccine trial remains paused in the US for a
Speaker 1: regulatory review of an incident where a participant developed unexplained
Speaker 1: neurological symptoms, including limb weakness, but the company said the
Speaker 1: symptoms probably weren't related to the shot itself. That's according
Speaker 1: to a letter the company sent to participants in the study.
Speaker 1: The letter reads quote After considering the information, the independent
Speaker 1: reviewers recommended the vaccinations should continue. India's virus cases reached
Speaker 1: the five million mark with the addition of more than
Speaker 1: ninety thousand new cases. The virus has been spreading in
Speaker 1: India at one of the fastest paces in the world.
Speaker 1: India has the third highest death toll from COVID nineteen,
Speaker 1: trailing the US and Brazil. The real number of infected
Speaker 1: and dead in India from COVID nineteen is likely far
Speaker 1: higher than the official numbers due to under reporting and
Speaker 1: inadequate testing. India's strict lockdown in clemented in late March
Speaker 1: to contain the outbreak, led to the biggest economic contraction
Speaker 1: of any major economy and now for today's main story.
Speaker 1: We've heard there are many things we can do to
Speaker 1: reduce the spread of the coronavirus, staying six ft away
Speaker 1: from someone else, washing our hands, and wearing a mask.
Speaker 1: But there's something else we can also do. Talk less.
Speaker 1: Speaking is a powerful generator of aerosols, the fine particles
Speaker 1: emitted from our mouths that can harbor the stars Cove
Speaker 1: two virus and potentially linger for hours in poorly ventilated spaces.
Speaker 1: Turns out, shutting up can help shut those particles down,
Speaker 1: and as Bloomberg Senior editor Jason Gale found out, it
Speaker 1: few must speak. It's safer if you do it softly.
Speaker 1: Aerosols are tiny particles emitted from our respiratory tracks that
Speaker 1: can stay aloft in ambient air for hours. There's been
Speaker 1: some debate about the role virus, light and eborne particles
Speaker 1: play and transmitting the COVID nineteen causing coronavirus. So I
Speaker 1: asked Bill Riston, party, professor of chemical engineering at the
Speaker 1: University of California, Davis, what we know about aerosols in
Speaker 1: the spread of the pandemic disease. That's a complicated question,
Speaker 1: of course, right because the contact racing referred so much
Speaker 1: about that that tells you who you likely got it
Speaker 1: from and when you likely got it, but it does
Speaker 1: not tell you by itself how you got it, whether
Speaker 1: those through a handshake or through them coughing your face
Speaker 1: or just talking and releasing infectious aerosol particles that travel
Speaker 1: across the room. But the indirect evidence implicating aerosols is mounting.
Speaker 1: The very first one that opened a lot of people's
Speaker 1: eyes was that outbreak of the choir practice up at
Speaker 1: Washington State. I think it was of the people who
Speaker 1: attended got infected just during a two n fur choir practice,
Speaker 1: and you know choir practice that's associated with loud vocalization.
Speaker 1: Then there was the Knees lunch in a restaurant in Guango, China,
Speaker 1: in which Tan Dinas came down with COVID nineteen. They
Speaker 1: had video evidence, which is really great. They showed that
Speaker 1: some of the people who got infected did not directly
Speaker 1: interact with the index case except by a virtue of
Speaker 1: the fact they're sharing the same air. Um, so they
Speaker 1: like did not you know, talk that didn't face to
Speaker 1: face and all that. So that's another piece of evidence
Speaker 1: for some type of long range transmission, and the expertory
Speaker 1: particles is the prime suspect. Then there have been outbreaks
Speaker 1: and bars whole Center and a cafe in South Korea
Speaker 1: and a bus in China. The whole focused attention on
Speaker 1: potentially infectious particles emitted from the respiratory tract. I asked Bill,
Speaker 1: how are these produced? There's at least three modes of
Speaker 1: respiratory droplet or respiratory particle generation. You know, sometimes you're
Speaker 1: you're talking and you see little drops of fluid come out.
Speaker 1: That's the so called oral mode, and that's mostly saliva um,
Speaker 1: an old fashioned word to spittle. Those those droplets if
Speaker 1: you can feel them hitting somebody or if you can
Speaker 1: see them. Relatively speaking, they're huge, way bigger than like say,
Speaker 1: fifty micrones, So they're like big boulders basically. And that's
Speaker 1: just one mode. The other two modes refer to much
Speaker 1: smaller particles that you can't see with the naked eye.
Speaker 1: One of them comes from the campillaries that line the
Speaker 1: bronchials in the far reaches of the lungs. When you
Speaker 1: exhale and you squeeze everything down your lungs, these little
Speaker 1: capillaries come together, kind of pinched together, and then you
Speaker 1: inhale and they expand and there's respiratory fluid lining those.
Speaker 1: And so when you do that in expanse, you have
Speaker 1: a little fluid film that kind of pinches off and
Speaker 1: leaves little satellite droplets, your daughter droplets that are now
Speaker 1: exhaled with your air. Bill says, these particles are about
Speaker 1: one micron in diameter. You know, I don't have much hair,
Speaker 1: but a typical human hair is about a hundred microns,
Speaker 1: so it's a hundred times smaller than the diameter of
Speaker 1: human hair. And so just breathing releases some of those.
Speaker 1: The other the third and final mode is the larrangel mode,
Speaker 1: so at the vocal chords. So when somebody says, uh,
Speaker 1: what's actually happening is you have these like little vocal
Speaker 1: words are opening and shutting at the frequency of your
Speaker 1: your pitch right, So I have kind of a deep voice.
Speaker 1: It's about a hundred twenty hurts. That means when I'm
Speaker 1: saying uh, literally, it's going like this a hundred twenty
Speaker 1: times a second. And these also have fluid lighting them.
Speaker 1: I should add here that Bill's lab has two high
Speaker 1: speed cameras that can capture images at more than one
Speaker 1: hundred thousand frames per second. He also has various optical
Speaker 1: and laser systems for visualizing the micro droplets that have
Speaker 1: created when we speak. So right now, as I've been talking,
Speaker 1: I've been emitting particles in the room right in front
Speaker 1: of me. And even though they're really tiny, too tiny
Speaker 1: to see, they're huge compared to the virus. So the
Speaker 1: virus can very happily be carried along in these micron
Speaker 1: skill So you have like a little little tiny bits
Speaker 1: of stunt, you know, basically floating around in the air
Speaker 1: that could be carrying the virus. The Bill's researchers showing
Speaker 1: that certain things can vary the emission of expertory particles.
Speaker 1: We found that speaking releases much more than breathing. And
Speaker 1: we went even further, and what we showed is that
Speaker 1: like how many particles emitted doing speech is a very
Speaker 1: strong function of how loud you are. So if you
Speaker 1: speak really loud, you emit a ton of way more
Speaker 1: than if you than if you required if you whisper.
Speaker 1: And some folks just emit a lot of particles. Bill says,
Speaker 1: some people are super emitters. So for whatever reason, um,
Speaker 1: some individuals when they talk just amit an order of
Speaker 1: magnitude more factor tend more than other people. And Bill
Speaker 1: says when some people cough for whatever reason, why more
Speaker 1: comes out. But these supermit is super spreaders of the coronavirus.
Speaker 1: That's a very challenge hypothesis to test post facto from
Speaker 1: an outbreak, but it's definitely a hypothesis that wants more investigation.
Speaker 1: If I was the virus in China affect as many people,
Speaker 1: I'd want to a super emitter who also was a
Speaker 1: super grower the virus, or like the virus was very successful,
Speaker 1: so you had a very high viral concentrations. And then
Speaker 1: I make sure if I was a virus again that
Speaker 1: I didn't make the person symptomatic, so they looked very healthy.
Speaker 1: And I'd have them go to a bar or a
Speaker 1: choir practice and have them sing and just vocalize as
Speaker 1: much as possible for a very long time. And I'd
Speaker 1: also tell the people to shut off the ventilation, uh
Speaker 1: so so that you know, to get the airborne viral
Speaker 1: concentration as high as possible. But also found that saying
Speaker 1: certain words it's associated with more particles admitted employs. It's
Speaker 1: like Papa produced more than fricatives like fafa but in
Speaker 1: general it was less important. Again if I was if
Speaker 1: I was a virus, I wouldn't care so much about
Speaker 1: what the word you're saying is. I would want to
Speaker 1: be in somebody who's saying it loudly. Right, So, in
Speaker 1: other words, minor changes and how loud you're articulating swamp
Speaker 1: out of the differences and what you're articulating. Does this
Speaker 1: mean people should be quiet for the sake of public health.
Speaker 1: I was advocating to some journalists who interviewed me back
Speaker 1: in April, and I said, I think we should start
Speaker 1: thinking about recommending people don't talk so much, especially in
Speaker 1: high risk of rooms like hospital wedding rooms. Back then,
Speaker 1: the report is looking at like that's crazy, but I
Speaker 1: think I think there is great to that. Now in September,
Speaker 1: that recommendation is sounding kind of sensible. We know that
Speaker 1: maintaining a physical distance, wearing a face mask, and thorough
Speaker 1: handwashing all helped to reduce the risk of spreading the coronavirus,
Speaker 1: but none is fail safe. It's doing them all together
Speaker 1: and quietly and offers the best chance at driving the
Speaker 1: pandemic into submission. That was Jason Gail, And that's it
Speaker 1: for our show Today. For coverage of the outbreak from
Speaker 1: one D and twenty bureaus around the world, visit bloomberg
Speaker 1: dot com Flash Coronavirus and if you like the show,
Speaker 1: please leave us a review and a rating on Apple
Speaker 1: Podcasts or Spotify. It's the best way to help more
Speaker 1: listeners find our global reporting. The Prognosis Daily edition is
Speaker 1: produced by topor foreheads Jordan gas Pure, Magnus Hendrickson, and
Speaker 1: me Laura Carlson. Today's main story was reported by Jason Gale.
Speaker 1: Original music by Leo Sidrin. Our editors are Rick Shine
Speaker 1: and Francesca Levi. Francesca Levi is Bloomberg's head of podcasts.
Speaker 1: Thanks for listening.