Welcome to Prognosis. I'm Laura Carlson. It's day one and twenty four since coronavirus was declared a global pandemic. Today's main story. Much of what we know suggests the virus is transmitted through tiny droplets from infected people, but researchers are now looking at tiny air assaults that linger in the air and whether they too can infect us. But first, here's what happened in virus news today. The World Health Organization had a sobering message at a briefing this morning.
COVID nineteen won't disappear quickly, and it's unrealistic to hang our hopes on a perfect vaccine emerging soon. You h Joe head tatris at Anam Gabrie Sus said strong government leadership was necessary and that fighting the virus is a long term commitment. In the US, the virus is making a comeback in states that thought they had already endured the worst of it. California, Louisiana, Michigan, and Washington State are seeing case counts climb again after months of declines.
It's not just a matter of more testing, hospitalizations, and in some places, deaths are rising too. Experts say the diseases on the rise in these states for the same reasons it's breaking records in places like Florida. Those reasons include a population no longer willing to stay inside, Republicans who refuse face masks as a political statement, street protests over police violence, and young people convinced the virus won't
seriously hurt them. Early in the pandemic, New York had one of the worst outbreaks in the US and took some of the strictest lockdown measures that has paid off. This weekend, New York City had its first day without a COVID nineteen death since the outbreak, But even there, officials are seeing a worrying trend. Cases are rising among people aged twenty nine. Today, Mayor build A Blasio said the city will work to educate young people on the
importance of wearing masks and keeping socially distant. And now for today's main story, we're learning more about how stars cove two, the virus that causes COVID nineteen, is spread from person to person. For the most part, it happens when we're in close contact with an infected person who we met. Tiny liquid particles by coughing, sneezing, speaking, or singing.
These droplets come out even when we just breathe. Normally, you get the virus by inhaling the droplets, having them travel into your ears or nose, or getting one stock on your hand which you then absentmindedly used to touch
in orifice. But at a New Year's lunch in China, a group of people got sick in a way that suggested there might be another way you can get COVID nineteen, Bloomberg Senior editor Jason Gale reports on the latest worry that virus laden aerosols floating in gas clouds could infect us. In China, the holidays main mass migration. People travel across the country to catch up with relatives, enjoy reunion dinners,
and hand out cash filled red envelopes to children. A family from Wuhan, the central Chinese city where the coronavirus emerged, was part of that mass movement. Back in January. This family of ten quarter train to the southern city of Guangzho the day before, having lunch in a crowded restaurant. It was the eve of the lunar New Year. What they didn't know at the time was that one of them, six year old art, was coming down with COVID nineteen.
A few hours after leaving the restaurant, the retiree developed a fever and cough. It means she was probably at her most infectious when she squeezed into a seat at a round table at the back of the restaurant as the family enjoyed lunch and air conditioner blue air across the back of the room where they were seated. That
was a few feet from two other families at neighboring tables. Importantly, their air conditioning unit on the wall facing the aren't incubating COVID was blowing air over all three tables, and it turns out that warm breeze and lunch were the
only things these families shared. A week and a half later, on February five, nine more of the diners had come down with COVID nineteen, four members of the Wuhan family plus five members of the two other families, but none of the waiters or seventy three other patrons in the room contracted the disease, and neither did anyone back at the Guangzho Hotel. Whether the Wuhan family was staying researchers
investigating the outbreak were in luck. There was a close circuit television camera in the restaurant, and the footage showed no close contact between each table's guests, aside from several seats being back to back. So to figure out how the virus spread over several meters, the researchers simulated the air flow across the three tables, and it pointed to what many scientists had feared. That is that the virus could be suspended and moved about in the ambient air
long enough and far enough to cause multiple infections. That this could occur is no surprise for Professor Ben Cowling, head of epidemiology and bios Statistics at the University of Hong Kong, then assisted China in the early study of the coronavirus. Is transmission dynamics. When I hear that transmissions going on after prolong closed contact, it makes me think that aerosols are playing a role mostly at short range, but in rooms where there's poorer ventilation, people spend a
longer period of time. You might see a little bit a long way to transmission. And we have seen outbreaks in coll centers. Enquired practices in restaurants and bars and nightclubs, and that's the kind of situations where where if their ventilation is not as good, you could see a bit of aerosols happening. The outbreak in the Guangho restaurant has become the touchstone in a global debate about how the coronavirus can spread in poorly ventilated spaces and the x
your measures that may be required to halt it. At the heart of the controversy remained lingering questions about how often such airborne transmission occurs. After all, the gang incident shows a majority of diners in the restaurant remained healthy, and so did roughly half of the people at the table where the infected woman from Woohan was sitting, and at the tables on either side of hers. He's been calling again. Yes, So in Hong Kong, we've we've done
a bit of that analysis. We've found that seventy of copy cases didn't pass infection to anyone else, and it was just a minority. It was a minority that caused on was transmission, and that's presumably a minority of cases are more contagious, and then among those, some of them have the potential to spread to lots of others, and so we have this super spreading phenomenon. And I think when there is super spreading going on, the most likely
explanation for that is also aerosoul transmission. But that's not to scare everybody. That's just to state that the fact that viruses can spread in this way and we need to be aware of that, and ventilation can be particularly important. The World Health Organization updated a scientific paper about the transmission of the Sasko V two virus on Thursday. It said it doesn't rule out the possibility of airborne transmission
in crowded areas or indoor venues with poor ventilation. However, the Geneva Base Agency said more researchers needed because in such cases there may be alternative explanations as to how people got sick, such as respiratory droplets that fell onto surfaces. The w h O faces pressure from scientists led by Lydia Morawska, director of the International Laboratory for Equality and
Health at Queensland University of Technology in Australia. Lydia argues that hamwashing and physical distancing alone aren't enough to stem infections because in the air and to research over the past three months found the presence of the spirals in the air and retrospectively that it incurreted people. Lydia and a colleague published an open letter in a medical journal last week calling on the w h O and other international groups to address the airborne transmission of COVID nineteen.
The letter documented research that was backed by two d and thirty nine scientists. It asked officials to consider such precautions as increasing ventilation and avoiding recirculating potentially virus late and air, and buildings like hospitals and schools to avoid the kind of scenario played out in the restaurant in Guangzho in January. What's being debated isn't what happens when an infected person coughs or sneezes globes of virus laden liquid.
That's a long established murder of infection. Rather, it's where the tiny particles known as microdroplets and aerosols stay afloat long enough to be inhaled and cause infection deeper in the lungs, and therefore what troll measures to use. Resolving these questions is becoming increasingly urgent as workplaces, schools, and colleges reopen in the United States, President Donald Trump has rejected school reopening guidelines that included increasing the circulation of
outdoor air as too difficult. I spoke with Lydia in late June, a week before her letter came out to help clear up some questions I had. Um. I think people have kind of mistakenly thought that there are droplets and then there are aerosols, and that it's very sort of binary, when in fact, there's a whole gradient of size of these particulars that come out of one's respiratory tract.
Can you talk about that, Well, there is a very big mess in in relation to the terminology, and it's often considered that this small part ticles emitted excribed by people are called aerosols and the pick are called droplets. It's nothing like this. Aerosols. The definition of aerosols are liquid and solid particles in the air. Now droplets are liquid particles, So basically droplets are liquid aerosols. So therefore we are not talking smaller be It has nothing to
do with size. Our breath isn't usually visible, but when it's really cold, we can see it as puffs of stain. Lidia said it's a helpful visualization of how virus leading particles of varying sizes can be expelled from an infected person in a turbulent gas cloud. But are these virus leading aerosols infectious? This depends on the condition of the
of the environment. Viruses of the skype are like cool air and drysh conditions, so if these are the conditions like in many office buildings, for example, this could be both conditions. If, on the other hand, we go outside where there is hot and in addition new we radiation, well within very short period of time, they will be deactivated, which suggests being outside is less risky for catching the coronavirus than being indoors well, very much so. But this
is not the only aspect, since you'll be radiation. It is the very fast dilution outdoors, which is a well large reservoir. Dilution is very fast, so therefore the airborne transmission outdoors has very little chances to walk. Of course, there is still that contact if you are standing next to somebody for long time and this person's misses that you or something like this, that's the close contact. But otherwise in the airborne transmission it's much less likely to
occur outdoors. In her letter last week, Lydia recommended high efficiency air filtration and jem sidle ultra violet lights they used to reduce the risk of airborne transmission. She also pointed to simpler protective measures like supplying clean out or air and avoiding overcrowding on public transport. Since siskov to emerge, Lydia's written or contributed to more than a dozen papers
on the potential for the pandemics airborne spread. This makes me even sort of more on acced determined to get something done about this, because once this pandemic is over, probably won't happen dead quickly at once the pandemic is over. Again, this and this is not the issues are not recognized and not taking Carl and we are we were in
the same situation during the next person. Evidence for airborne transmission of the coronavirus is still emerging and incomplete examples like the Gango restaurant suggests it's the most plausible explanation for how people were infected in some situations. While scientists conduct further research to better understand why, how, and to what extent these microscopic particles can spread, COVID nineteen. There
are things we can do to mitigate that risk. Stay home if you're sick, coffin, sneeze into your elbow, observe physical distancing recommendations, avoid crowded, poorly ventilated indoor spaces, and where it's appropriate, where a face mask. That was Jason Gale in Melbourne. And that's it for our show. For coverage of the outbreak from one and twenty bureaus around the world, visit Bloomberg dot com slash coronavirus and if you like the show, please leave us a review and
a rating on Apple Podcasts or Spotify. It's the best way to help more listeners find our global reporting. The Prognosis Daily edition is produced by Topher Foreheads Jordan Gaspore, Magnus Hendrickson and me Laura Carlson. Today's main story was reported by Jason Gale. Original music by Leo Sidran. Our editors are Rick Shine and Francesca Levi. Francesca Levie is Bloomberg's head of podcasts. Thanks for listening.