1 00:00:06,640 --> 00:00:11,760 Speaker 1: Welcome to Prognosis. I'm Laura Carlson. It's day nine one 2 00:00:12,119 --> 00:00:16,640 Speaker 1: since coronavirus was declared a global pandemic. Our main story. 3 00:00:17,680 --> 00:00:22,160 Speaker 1: A top World Health Organization official sparked a controversy earlier 4 00:00:22,200 --> 00:00:27,160 Speaker 1: this week over comments regarding asymptomatic carriers of COVID nineteen. 5 00:00:28,480 --> 00:00:32,879 Speaker 1: She first said instances of asymptomatic carriers spreading the virus 6 00:00:33,000 --> 00:00:39,879 Speaker 1: are very rare, before later clarifying her remarks. We explore 7 00:00:40,000 --> 00:00:43,080 Speaker 1: why some people don't get sick after they're infected with 8 00:00:43,120 --> 00:00:46,320 Speaker 1: the virus and why their role in its spread is 9 00:00:46,400 --> 00:01:00,280 Speaker 1: still unclear. But first, here's what happened today. The World 10 00:01:00,320 --> 00:01:03,560 Speaker 1: Health Organization said today that a persistent increase in cases 11 00:01:03,600 --> 00:01:07,920 Speaker 1: in Latin America is of deep concern as hospitals across 12 00:01:07,920 --> 00:01:12,639 Speaker 1: the region come under increasing strain. This comes one day 13 00:01:12,680 --> 00:01:17,640 Speaker 1: after Anthony Fauci, the US government's top infectious disease expert, 14 00:01:18,000 --> 00:01:22,640 Speaker 1: said the pandemic is far from over. China is offering 15 00:01:22,640 --> 00:01:26,399 Speaker 1: employees of some large state run companies the option to 16 00:01:26,480 --> 00:01:31,480 Speaker 1: be inoculated with two vaccines currently in development. The government 17 00:01:31,480 --> 00:01:34,440 Speaker 1: would only hand out the vaccine to workers intending to 18 00:01:34,520 --> 00:01:40,640 Speaker 1: travel overseas. The European Union plans a gradual and partial 19 00:01:40,680 --> 00:01:43,320 Speaker 1: easing of a ban on most travel to the block 20 00:01:43,800 --> 00:01:49,560 Speaker 1: beginning July one. In May, the price of whitebread dropped 21 00:01:49,720 --> 00:01:53,560 Speaker 1: the most since World War Two. That's according to the 22 00:01:53,600 --> 00:01:58,800 Speaker 1: Bureau of Labor Statistics. Dress prices and car insurance fell 23 00:01:58,920 --> 00:02:02,880 Speaker 1: by the most on Kurt. Months of quarantine. It appears, 24 00:02:03,080 --> 00:02:06,920 Speaker 1: have turned stay at home Americans into home bakers and 25 00:02:07,040 --> 00:02:11,520 Speaker 1: lowered demand for anything but casual clothing as weakness across 26 00:02:11,639 --> 00:02:16,440 Speaker 1: most categories pushed the overall consumer price index lower for 27 00:02:16,480 --> 00:02:28,120 Speaker 1: a third month and now our main story. A comment 28 00:02:28,200 --> 00:02:31,240 Speaker 1: by a w h O official earlier this week caught 29 00:02:31,280 --> 00:02:35,120 Speaker 1: many health experts off guard. She threw doubt on what 30 00:02:35,200 --> 00:02:39,800 Speaker 1: has been accepted for months. Silent spreaders, carriers of the 31 00:02:39,840 --> 00:02:44,520 Speaker 1: coronavirus who don't show symptoms readily transmit the disease to others. 32 00:02:45,560 --> 00:02:49,919 Speaker 1: The official later clarified her comments, But just how risky 33 00:02:50,160 --> 00:02:56,480 Speaker 1: are these asymptomatic carriers? Bloomberg Senior editor Jason Gale helps 34 00:02:56,600 --> 00:03:06,639 Speaker 1: us untangle the issue. Back in February, the Diamond Princess 35 00:03:06,639 --> 00:03:09,520 Speaker 1: cruise ship was the center of an explosive outbreak of 36 00:03:09,560 --> 00:03:13,200 Speaker 1: the coronavirus when it was quarantined in Japan. Of some 37 00:03:13,280 --> 00:03:16,120 Speaker 1: three thousand, seven hundred and eleven passengers and crew on 38 00:03:16,240 --> 00:03:19,919 Speaker 1: board the luxury ship, almost a fifth caught it at 39 00:03:19,960 --> 00:03:23,720 Speaker 1: the time of testing. Surprisingly, most of those infected didn't 40 00:03:23,720 --> 00:03:27,880 Speaker 1: have fever, dry cough, or difficulty breathing, the usual symptoms 41 00:03:27,880 --> 00:03:32,000 Speaker 1: of COVID nineteen, and when doctors followed those asymptomatic cases 42 00:03:32,040 --> 00:03:35,360 Speaker 1: for weeks, they found that just under half never developed 43 00:03:35,400 --> 00:03:39,920 Speaker 1: any disease. That contradicted initial findings from the World Health Organization. 44 00:03:40,600 --> 00:03:44,400 Speaker 1: The agency said in March that asymptomatic infections are rare, 45 00:03:45,120 --> 00:03:47,920 Speaker 1: but since then reports from around the world have shown 46 00:03:47,920 --> 00:03:52,240 Speaker 1: that asymptomatic cases aren't swer rare, and in some instances 47 00:03:52,600 --> 00:04:00,800 Speaker 1: they might be the source of infections. The majority of 48 00:04:00,840 --> 00:04:02,960 Speaker 1: transmission that we know about is that people who have 49 00:04:03,040 --> 00:04:06,240 Speaker 1: symptoms transmit the virus to other people through infectious ruplets. 50 00:04:06,760 --> 00:04:10,480 Speaker 1: That's Maria van Kirkhoff, the whose technical lead on COVID nineteen, 51 00:04:10,840 --> 00:04:14,120 Speaker 1: speaking during a Facebook live event in Geneva on Tuesday. 52 00:04:14,520 --> 00:04:16,960 Speaker 1: She was clarifying comments she made earlier in the week 53 00:04:17,279 --> 00:04:19,520 Speaker 1: about the risk of the virus spreading from people who 54 00:04:19,560 --> 00:04:22,440 Speaker 1: don't have symptoms. We do know that some people who 55 00:04:22,480 --> 00:04:25,200 Speaker 1: are asymptomatic. Are some people who don't have symptoms can 56 00:04:25,240 --> 00:04:28,640 Speaker 1: transmit the virus on and so what we need to 57 00:04:28,680 --> 00:04:31,599 Speaker 1: better understand is how many of the people in the 58 00:04:31,600 --> 00:04:34,920 Speaker 1: population don't have symptoms, and separately, how many of those 59 00:04:34,960 --> 00:04:46,040 Speaker 1: individuals go on to transmit to others. The extent to 60 00:04:46,120 --> 00:04:51,200 Speaker 1: which these silent carriers may also be silent spreaders isn't clear, 61 00:04:51,600 --> 00:04:54,680 Speaker 1: and it probably varies between groups of people because the 62 00:04:54,720 --> 00:04:59,160 Speaker 1: fact is, like age, genetics, underlying medical conditions, and people's 63 00:04:59,240 --> 00:05:04,000 Speaker 1: individual and une responses, Uncertainty over how the virus behaves 64 00:05:04,040 --> 00:05:07,960 Speaker 1: has hindered nation's efforts to reopen bantered economies. If there 65 00:05:08,000 --> 00:05:10,679 Speaker 1: are a lot of people in the community sharing crowded 66 00:05:10,720 --> 00:05:14,279 Speaker 1: subway trains who don't know they're infected, well that's a 67 00:05:14,279 --> 00:05:18,359 Speaker 1: big problem if they're also contagious. Dr Peter colign On, 68 00:05:18,600 --> 00:05:21,599 Speaker 1: professor of medicine at the Australian National University in Canberra, 69 00:05:21,920 --> 00:05:26,880 Speaker 1: says it's less likely individuals without respiratory symptoms will spread 70 00:05:26,880 --> 00:05:29,760 Speaker 1: the virus simply because they're not coughing and spluttering on 71 00:05:29,839 --> 00:05:34,240 Speaker 1: other people. I actually do think asymptomatics cause less infection 72 00:05:34,279 --> 00:05:37,240 Speaker 1: than symptomatics, maybe because they're not sneezing or coughing as 73 00:05:37,279 --> 00:05:39,880 Speaker 1: much and therefore they're not spreading droplets as much. Is 74 00:05:39,920 --> 00:05:43,039 Speaker 1: there's a few studies that show that of cases are 75 00:05:43,120 --> 00:05:47,680 Speaker 1: due to people so super spreaders, but that still leaves 76 00:05:47,680 --> 00:05:51,400 Speaker 1: who are dcovers for Since infected people without symptoms aren't 77 00:05:51,400 --> 00:05:54,880 Speaker 1: in bed nursing their illness, they are typically more mobile, 78 00:05:55,080 --> 00:05:58,680 Speaker 1: which does present an infection risk. A simple nose rub 79 00:05:58,720 --> 00:06:01,520 Speaker 1: could transfer virus party calls to a hand that could 80 00:06:01,560 --> 00:06:04,320 Speaker 1: then touch a doorknob or a force it which someone 81 00:06:04,360 --> 00:06:06,800 Speaker 1: else might touch and then rub their eye or mouth, 82 00:06:06,880 --> 00:06:12,080 Speaker 1: inoculating themselves and causing an infection. So we've got to 83 00:06:12,080 --> 00:06:16,080 Speaker 1: actually assume that people with minimum symptoms are still a 84 00:06:16,200 --> 00:06:18,720 Speaker 1: risk for having the virus and being able to spread it. 85 00:06:19,320 --> 00:06:22,599 Speaker 1: And that actually means that's good news in the community 86 00:06:22,640 --> 00:06:24,360 Speaker 1: because it means we can keep on doing a whole 87 00:06:24,400 --> 00:06:28,080 Speaker 1: lot of things within limits. But we've got to just 88 00:06:28,200 --> 00:06:31,400 Speaker 1: assume it's there at low levels and therefore take all 89 00:06:31,440 --> 00:06:33,640 Speaker 1: the precautions we have to not let us spread. So 90 00:06:33,720 --> 00:06:36,719 Speaker 1: the hand hygiene, the physical distancing don't go to work 91 00:06:36,760 --> 00:06:39,520 Speaker 1: if you've got any symptoms, et cetera. That decreases the risk, 92 00:06:39,560 --> 00:06:42,640 Speaker 1: but it doesn't make the risk of zero. Peter says 93 00:06:42,680 --> 00:06:45,920 Speaker 1: that in countries where the coronavirus is spreading out of control, 94 00:06:46,360 --> 00:06:50,200 Speaker 1: it makes sense for public health officials to target symptomatic cases, 95 00:06:50,600 --> 00:06:53,040 Speaker 1: isolate them and trace who they have been in contact 96 00:06:53,080 --> 00:06:56,760 Speaker 1: with the monitor for further spread. But in countries where 97 00:06:56,760 --> 00:06:59,840 Speaker 1: there is little or no obvious transmission going on, it 98 00:07:00,000 --> 00:07:03,160 Speaker 1: is important to hunt down all infections. I think the 99 00:07:03,200 --> 00:07:06,280 Speaker 1: asymptomatics are still important, particularly if you want to get 100 00:07:06,360 --> 00:07:09,640 Speaker 1: levels of virus at very low levels of transmission. I mean, 101 00:07:09,680 --> 00:07:12,600 Speaker 1: if you're in a country where it's out of control, okay, yeah, 102 00:07:12,760 --> 00:07:15,520 Speaker 1: concentrate on the symptomatics. I don't have a problem with that. 103 00:07:15,880 --> 00:07:18,920 Speaker 1: But if you're in a situation like Career in New 104 00:07:19,000 --> 00:07:23,640 Speaker 1: Zealand Australia, the the asymptomatics are also important to find 105 00:07:24,440 --> 00:07:27,400 Speaker 1: um and once Europe gets down to low levels, that's 106 00:07:27,440 --> 00:07:30,080 Speaker 1: going to be equally important because otherwise you find next 107 00:07:30,080 --> 00:07:37,080 Speaker 1: winter you're back in the same problem again. Infected people 108 00:07:37,120 --> 00:07:40,120 Speaker 1: can also spread the virus via droplets that come out 109 00:07:40,160 --> 00:07:43,600 Speaker 1: of them mouths in ways that don't require coffee. Dr 110 00:07:43,640 --> 00:07:46,480 Speaker 1: SONJ Sent and I care An infectious diseases. Physician in 111 00:07:46,520 --> 00:07:49,640 Speaker 1: Canberra says that could be important as communities come out 112 00:07:49,640 --> 00:07:52,880 Speaker 1: of lockdown, especially in the context of large gatherings like 113 00:07:53,000 --> 00:07:57,400 Speaker 1: protest marches. There may be certain scenarios where an asymptomatic 114 00:07:57,440 --> 00:08:03,760 Speaker 1: person maybe create eating more droplets or perhaps even aerosolizing 115 00:08:03,760 --> 00:08:06,440 Speaker 1: a bit. For example, in a choir practice. We've had 116 00:08:06,640 --> 00:08:11,600 Speaker 1: outbreaks in acquire setting in a loud nightclub where you 117 00:08:11,680 --> 00:08:14,800 Speaker 1: have to shout a lot, or a protest or or 118 00:08:14,880 --> 00:08:18,600 Speaker 1: some other event where someone won't be speaking normally. They 119 00:08:18,680 --> 00:08:22,760 Speaker 1: might be therefore generating more droplets, and in that situation 120 00:08:22,800 --> 00:08:26,040 Speaker 1: in a symptomatic person might be able to spread to 121 00:08:26,720 --> 00:08:29,760 Speaker 1: someone else that way. So j I agrees that the 122 00:08:29,880 --> 00:08:33,360 Speaker 1: likelihood of onward transmission is lower in a person without 123 00:08:33,480 --> 00:08:37,679 Speaker 1: respiratory symptoms compared with someone who's coughing. Problem is, there 124 00:08:37,679 --> 00:08:40,240 Speaker 1: are a lot of people who are infected without symptoms, 125 00:08:40,600 --> 00:08:43,240 Speaker 1: and there sheer number alone amplifies the risk of some 126 00:08:43,320 --> 00:08:48,160 Speaker 1: transmission occurring. There are a lot of asymptomatic infections out 127 00:08:48,200 --> 00:08:52,600 Speaker 1: there and will only work out that proportion ultimately when 128 00:08:52,640 --> 00:08:56,600 Speaker 1: we have a good antibody test, So good zero surveys 129 00:08:56,679 --> 00:09:00,080 Speaker 1: will will give us that answer, And of course it 130 00:09:00,200 --> 00:09:04,520 Speaker 1: is kind of hard because is someone truly asymptomatic if 131 00:09:04,559 --> 00:09:07,560 Speaker 1: they're feeling a little bit under the weather, or are 132 00:09:07,600 --> 00:09:12,240 Speaker 1: they actually symptomatic. So there are those those slight subtleties 133 00:09:12,280 --> 00:09:15,640 Speaker 1: in definition we have to think about. Jia says, the 134 00:09:15,720 --> 00:09:19,960 Speaker 1: prospect that asymptomatically infected people are less likely to spread 135 00:09:19,960 --> 00:09:23,720 Speaker 1: the virus doesn't mean we should abolish physical distancing and 136 00:09:23,760 --> 00:09:27,040 Speaker 1: other measures to control the pandemic. Not now, not until 137 00:09:27,040 --> 00:09:28,760 Speaker 1: we get a vaccine. I think we have to be 138 00:09:28,840 --> 00:09:32,440 Speaker 1: very careful about that. Low risk is not no risk, 139 00:09:33,280 --> 00:09:35,719 Speaker 1: and we've seen the consequences of what can happen if 140 00:09:35,720 --> 00:09:39,880 Speaker 1: there is a super spreader event. Uh, it has all 141 00:09:39,880 --> 00:09:46,160 Speaker 1: the downstream effects, the impact on our health system, our economy, socially, 142 00:09:46,679 --> 00:09:50,720 Speaker 1: it's just a disaster. So we have to be very 143 00:09:50,840 --> 00:09:56,280 Speaker 1: very careful. But still except that asymptomatic transmission is lower risk, 144 00:09:56,720 --> 00:10:00,160 Speaker 1: but it is still not no risk. The coronavirus US 145 00:10:00,320 --> 00:10:03,720 Speaker 1: has a way of exploiting our vulnerabilities when we allow 146 00:10:03,760 --> 00:10:08,200 Speaker 1: it to spread. Undetected cases can snowball quickly. The only 147 00:10:08,280 --> 00:10:11,360 Speaker 1: sure fireway to counter it is to limit its ability 148 00:10:11,400 --> 00:10:14,880 Speaker 1: to infect others. As the w A chose said on Tuesday, 149 00:10:15,280 --> 00:10:19,200 Speaker 1: in the absence of a vaccine, testing, quarantining and contact 150 00:10:19,200 --> 00:10:36,080 Speaker 1: tracing remain our best defense against this insidious disease. That 151 00:10:36,160 --> 00:10:39,800 Speaker 1: was Jason Gale, and that's our show today. For coverage 152 00:10:39,840 --> 00:10:43,280 Speaker 1: of the outbreak from one bureaus around the world, visit 153 00:10:43,320 --> 00:10:48,160 Speaker 1: bloomberg dot com slash coronavirus and if you like the show, 154 00:10:48,640 --> 00:10:51,560 Speaker 1: please leave us a review and a rating on Apple 155 00:10:51,640 --> 00:10:55,079 Speaker 1: Podcasts or Spotify. It's the best way to help more 156 00:10:55,160 --> 00:11:00,120 Speaker 1: listeners find our global reporting. The Prognosis Daily edition is 157 00:11:00,120 --> 00:11:05,280 Speaker 1: produced by Topher Foreheads Jordan Gaspure, Magnus Hendrikson and me 158 00:11:05,880 --> 00:11:10,280 Speaker 1: Laura Carlson. Today's main story was reported by Jason Gale. 159 00:11:11,120 --> 00:11:15,760 Speaker 1: Original music by Leo Sedrin. Our editors are Francesco Levi 160 00:11:16,040 --> 00:11:20,680 Speaker 1: and Rick Shine. Francesco Levi is Bloomberg's head of podcasts. 161 00:11:21,240 --> 00:11:22,120 Speaker 1: Thanks for listening.