Speaker 1: Welcome to Prognosis. I'm Laura Carlson. It's day nine one
Speaker 1: since coronavirus was declared a global pandemic. Our main story.
Speaker 1: A top World Health Organization official sparked a controversy earlier
Speaker 1: this week over comments regarding asymptomatic carriers of COVID nineteen.
Speaker 1: She first said instances of asymptomatic carriers spreading the virus
Speaker 1: are very rare, before later clarifying her remarks. We explore
Speaker 1: why some people don't get sick after they're infected with
Speaker 1: the virus and why their role in its spread is
Speaker 1: still unclear. But first, here's what happened today. The World
Speaker 1: Health Organization said today that a persistent increase in cases
Speaker 1: in Latin America is of deep concern as hospitals across
Speaker 1: the region come under increasing strain. This comes one day
Speaker 1: after Anthony Fauci, the US government's top infectious disease expert,
Speaker 1: said the pandemic is far from over. China is offering
Speaker 1: employees of some large state run companies the option to
Speaker 1: be inoculated with two vaccines currently in development. The government
Speaker 1: would only hand out the vaccine to workers intending to
Speaker 1: travel overseas. The European Union plans a gradual and partial
Speaker 1: easing of a ban on most travel to the block
Speaker 1: beginning July one. In May, the price of whitebread dropped
Speaker 1: the most since World War Two. That's according to the
Speaker 1: Bureau of Labor Statistics. Dress prices and car insurance fell
Speaker 1: by the most on Kurt. Months of quarantine. It appears,
Speaker 1: have turned stay at home Americans into home bakers and
Speaker 1: lowered demand for anything but casual clothing as weakness across
Speaker 1: most categories pushed the overall consumer price index lower for
Speaker 1: a third month and now our main story. A comment
Speaker 1: by a w h O official earlier this week caught
Speaker 1: many health experts off guard. She threw doubt on what
Speaker 1: has been accepted for months. Silent spreaders, carriers of the
Speaker 1: coronavirus who don't show symptoms readily transmit the disease to others.
Speaker 1: The official later clarified her comments, But just how risky
Speaker 1: are these asymptomatic carriers? Bloomberg Senior editor Jason Gale helps
Speaker 1: us untangle the issue. Back in February, the Diamond Princess
Speaker 1: cruise ship was the center of an explosive outbreak of
Speaker 1: the coronavirus when it was quarantined in Japan. Of some
Speaker 1: three thousand, seven hundred and eleven passengers and crew on
Speaker 1: board the luxury ship, almost a fifth caught it at
Speaker 1: the time of testing. Surprisingly, most of those infected didn't
Speaker 1: have fever, dry cough, or difficulty breathing, the usual symptoms
Speaker 1: of COVID nineteen, and when doctors followed those asymptomatic cases
Speaker 1: for weeks, they found that just under half never developed
Speaker 1: any disease. That contradicted initial findings from the World Health Organization.
Speaker 1: The agency said in March that asymptomatic infections are rare,
Speaker 1: but since then reports from around the world have shown
Speaker 1: that asymptomatic cases aren't swer rare, and in some instances
Speaker 1: they might be the source of infections. The majority of
Speaker 1: transmission that we know about is that people who have
Speaker 1: symptoms transmit the virus to other people through infectious ruplets.
Speaker 1: That's Maria van Kirkhoff, the whose technical lead on COVID nineteen,
Speaker 1: speaking during a Facebook live event in Geneva on Tuesday.
Speaker 1: She was clarifying comments she made earlier in the week
Speaker 1: about the risk of the virus spreading from people who
Speaker 1: don't have symptoms. We do know that some people who
Speaker 1: are asymptomatic. Are some people who don't have symptoms can
Speaker 1: transmit the virus on and so what we need to
Speaker 1: better understand is how many of the people in the
Speaker 1: population don't have symptoms, and separately, how many of those
Speaker 1: individuals go on to transmit to others. The extent to
Speaker 1: which these silent carriers may also be silent spreaders isn't clear,
Speaker 1: and it probably varies between groups of people because the
Speaker 1: fact is, like age, genetics, underlying medical conditions, and people's
Speaker 1: individual and une responses, Uncertainty over how the virus behaves
Speaker 1: has hindered nation's efforts to reopen bantered economies. If there
Speaker 1: are a lot of people in the community sharing crowded
Speaker 1: subway trains who don't know they're infected, well that's a
Speaker 1: big problem if they're also contagious. Dr Peter colign On,
Speaker 1: professor of medicine at the Australian National University in Canberra,
Speaker 1: says it's less likely individuals without respiratory symptoms will spread
Speaker 1: the virus simply because they're not coughing and spluttering on
Speaker 1: other people. I actually do think asymptomatics cause less infection
Speaker 1: than symptomatics, maybe because they're not sneezing or coughing as
Speaker 1: much and therefore they're not spreading droplets as much. Is
Speaker 1: there's a few studies that show that of cases are
Speaker 1: due to people so super spreaders, but that still leaves
Speaker 1: who are dcovers for Since infected people without symptoms aren't
Speaker 1: in bed nursing their illness, they are typically more mobile,
Speaker 1: which does present an infection risk. A simple nose rub
Speaker 1: could transfer virus party calls to a hand that could
Speaker 1: then touch a doorknob or a force it which someone
Speaker 1: else might touch and then rub their eye or mouth,
Speaker 1: inoculating themselves and causing an infection. So we've got to
Speaker 1: actually assume that people with minimum symptoms are still a
Speaker 1: risk for having the virus and being able to spread it.
Speaker 1: And that actually means that's good news in the community
Speaker 1: because it means we can keep on doing a whole
Speaker 1: lot of things within limits. But we've got to just
Speaker 1: assume it's there at low levels and therefore take all
Speaker 1: the precautions we have to not let us spread. So
Speaker 1: the hand hygiene, the physical distancing don't go to work
Speaker 1: if you've got any symptoms, et cetera. That decreases the risk,
Speaker 1: but it doesn't make the risk of zero. Peter says
Speaker 1: that in countries where the coronavirus is spreading out of control,
Speaker 1: it makes sense for public health officials to target symptomatic cases,
Speaker 1: isolate them and trace who they have been in contact
Speaker 1: with the monitor for further spread. But in countries where
Speaker 1: there is little or no obvious transmission going on, it
Speaker 1: is important to hunt down all infections. I think the
Speaker 1: asymptomatics are still important, particularly if you want to get
Speaker 1: levels of virus at very low levels of transmission. I mean,
Speaker 1: if you're in a country where it's out of control, okay, yeah,
Speaker 1: concentrate on the symptomatics. I don't have a problem with that.
Speaker 1: But if you're in a situation like Career in New
Speaker 1: Zealand Australia, the the asymptomatics are also important to find
Speaker 1: um and once Europe gets down to low levels, that's
Speaker 1: going to be equally important because otherwise you find next
Speaker 1: winter you're back in the same problem again. Infected people
Speaker 1: can also spread the virus via droplets that come out
Speaker 1: of them mouths in ways that don't require coffee. Dr
Speaker 1: SONJ Sent and I care An infectious diseases. Physician in
Speaker 1: Canberra says that could be important as communities come out
Speaker 1: of lockdown, especially in the context of large gatherings like
Speaker 1: protest marches. There may be certain scenarios where an asymptomatic
Speaker 1: person maybe create eating more droplets or perhaps even aerosolizing
Speaker 1: a bit. For example, in a choir practice. We've had
Speaker 1: outbreaks in acquire setting in a loud nightclub where you
Speaker 1: have to shout a lot, or a protest or or
Speaker 1: some other event where someone won't be speaking normally. They
Speaker 1: might be therefore generating more droplets, and in that situation
Speaker 1: in a symptomatic person might be able to spread to
Speaker 1: someone else that way. So j I agrees that the
Speaker 1: likelihood of onward transmission is lower in a person without
Speaker 1: respiratory symptoms compared with someone who's coughing. Problem is, there
Speaker 1: are a lot of people who are infected without symptoms,
Speaker 1: and there sheer number alone amplifies the risk of some
Speaker 1: transmission occurring. There are a lot of asymptomatic infections out
Speaker 1: there and will only work out that proportion ultimately when
Speaker 1: we have a good antibody test, So good zero surveys
Speaker 1: will will give us that answer, And of course it
Speaker 1: is kind of hard because is someone truly asymptomatic if
Speaker 1: they're feeling a little bit under the weather, or are
Speaker 1: they actually symptomatic. So there are those those slight subtleties
Speaker 1: in definition we have to think about. Jia says, the
Speaker 1: prospect that asymptomatically infected people are less likely to spread
Speaker 1: the virus doesn't mean we should abolish physical distancing and
Speaker 1: other measures to control the pandemic. Not now, not until
Speaker 1: we get a vaccine. I think we have to be
Speaker 1: very careful about that. Low risk is not no risk,
Speaker 1: and we've seen the consequences of what can happen if
Speaker 1: there is a super spreader event. Uh, it has all
Speaker 1: the downstream effects, the impact on our health system, our economy, socially,
Speaker 1: it's just a disaster. So we have to be very
Speaker 1: very careful. But still except that asymptomatic transmission is lower risk,
Speaker 1: but it is still not no risk. The coronavirus US
Speaker 1: has a way of exploiting our vulnerabilities when we allow
Speaker 1: it to spread. Undetected cases can snowball quickly. The only
Speaker 1: sure fireway to counter it is to limit its ability
Speaker 1: to infect others. As the w A chose said on Tuesday,
Speaker 1: in the absence of a vaccine, testing, quarantining and contact
Speaker 1: tracing remain our best defense against this insidious disease. That
Speaker 1: was Jason Gale, and that's our show today. For coverage
Speaker 1: of the outbreak from one bureaus around the world, visit
Speaker 1: bloomberg dot com slash 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 Topher Foreheads Jordan Gaspure, Magnus Hendrikson and me
Speaker 1: Laura Carlson. Today's main story was reported by Jason Gale.
Speaker 1: Original music by Leo Sedrin. Our editors are Francesco Levi
Speaker 1: and Rick Shine. Francesco Levi is Bloomberg's head of podcasts.
Speaker 1: Thanks for listening.