She's Electra in Global Health at ST George's University of London.

She's an expert on the spread of viruses and social distancing measures on them.

Also joined from the University of Cambridge by the virologist in Presenter Off the naked scientist podcast Dr Chris Smith.

Welcome to you both.

Maybe I could start with you, Dr Chris Smith on masks because there's a lot of talk at the moment about masks.

And here is one from Terrence in Newport in Wales.

Can I make a mascot home on what would be the best material on once used wood?

The fire US be destroyed by cleaning or heating it.

Hello, Terrence.

To be honest with you, the current evidence we have in the guidance that public health England is sticking to is that these masks, they're not gonna be helpful in in the hospital setting used appropriately the right sort of mask in the right sort of setting, with the right sorts of additional protection, including protection for your eyes.

They can save lives that can be very helpful.

But general public walking around in the supermarket for example, getting your shopping they're probably not going to do you any good.

The only possible exception to this is if you wear a mask in your highly symptomatic and you're coughing and spluttering, they might cut down the creation of what we call an aerosol, the release of virus particles into the air around you that might then go on to infect other people.

They might reduce that a bit, but the kinds of masks available to the general public and the materials they're made off don't actually cut down as far as we can tell the transmission any better than just adopting the other social distancing and hygiene measures that the government are urging you to use because there's a debate now, isn't it?

In the United States, the mayor's in Los Angeles on din, New York is saying where anything to cut down, as you say, The Aris Elif act.

Yeah, there's not really any compelling evidence behind this.

What we do know about these masses that usually people don't fit them properly and they don't form an airtight seal around your mouth.

And in fact, I was watching a television program the other night.

Some people in Italy, and from the camera angle, I could see the individuals mouth around the side of the mask.

Now, if I could see it from a television camera, that means the virus, which is 1 10/1000 of a millimetre across.

That's a gaping great hole for the virus to sneak in through.

No problem there, so people end up with air leaking around them.

Also, if you've got something on your face, it tends to encourage you to touch your face more often, not less often.

And that means if you've touched a surface that has the virus on it, there's a chance that you could then transfer the virus to the mask on.

With prolonged wearing, they tend to get damp and that dampness actually encourages virus particles to go through the mask so you could actually increase the chances of picking up the virus.

So it's better to just follow the guidance.

We think that the moment that the government giving out, which is stay away from people because people are the only source you've got to catch this virus man infected person, that's the only source.

Wash your hands in case you've touched the surface that might have viruses on it and stay at home.

Good advice.

Sadly, the death rate is rising.

Elisabetta.

Here's a question some of asked from Eileen O'Toole When a person dies of the virus, does the virus die, too?

So the short answer is that, yes, it will, but unfortunately no, exactly at the same time as the person so that the virus we know can survive on surfaces.

And so it will be able to survive, as you know, into tiny in the hours after a person has, unfortunately died.

And so it's crucial that, you know appropriate PP is actually used to prepare the body for funeral in forbearers and also is absolutely crucial.

And there are recommendations off about maintaining social distancing during a funeral itself on.

Is this why we're having such tight regulations around funerals?

Absolutely.

And I am.

I am from Italy, where funerals are a big event with lots of people, and those have bean, particularly in spelt out in the legislation's about it.

Only two or three straight close family members that could be allowed to participate at a funeral.

Okay, here's one Chris from John Killing in Bedford, Bedfordshire, who is being tested.

Everyone with symptoms, or are they testing to see who has it?

Okay, The government have drawn up a specific case definition.

If you've got the symptoms on, those include a fever, which is more than 37 about half those embolism degrees and you have a new cough.

That's how we're defining someone who's potentially infected at the moment.

If you have those symptoms and you've come into hospital and we need to bring you into hospital for treatment, then we would do a test on you at that stage because we need to know what you've got wrong with you and what you got wrong.

Withyou determines how you get treated and where in the hospital your put, because one of the most important priorities is to do infection control and we cohort patients.

What that means is we put people together who have either not got the virus or have got the virus, because in that way we're not spreading the infection to uninfected at risk people.

So that's one group.

The other group that can get it tested under Matt Hancocks, number one pillar these air healthcare workers because we know that a significant number of people are currently at home who could be at the front line, and this is because a member of their family or they themselves have some of these symptoms.

But because the symptoms are so common and their shared with many other respiratory infections, it could well be that they don't have Corona virus.

They have something else much more trivial on.

They don't need to worry, so testing them will enable us to return more members of staff to the front line.

As the number of tests increases towards the goal of public health.

England think we need about 25,000 tests to be done per day in order to meet the needs of doing our healthcare.

How we gonna move patients around, test our healthcare workers.

Then once we get to that stage, other pillars of the testing algorithm will kick in, and that means we'll be able to test more.

People potentially also test people for long term immunity, but at the moment it's all about who's got the virus right now so we can sort out whose infectious and who's not.

Elisabetta health secretary said yesterday they'd supplied 45 million pieces of peopie masks, gloves, gowns to the N.

H.

S in one day.

So Sandy Goldsmith from ministry.

And can I ask, what happens to all that used peopIe?

Is it being recycled?

Is it burned?

Is it laundered?

What happens to it?

Unfortunately, if the people here has been used in a in a healthcare environment, especially in the context salt, infectious diseases, that large amount of pee pee is gonna have to be disposed of safely and appropriately, and the usual channels to dispose of this off this waste.

There is absolutely no recycling, but it's actually incineration.

I know it's a large amount, but it's the only way that actually make sure that we are safe because reusing increases, the chance is over, you know, transmitting infection.

Chris, I don't know if you go for a Boris run every day.

I know I do it any way I could get by.

But Fiona Marlowe asked from Weymouth in Dorset when I walked for my daily exercise.

There are lots of runners like Christian on cyclists who passed me breathing heavily.

Am I at risk of contracting the virus?

What if you get close to another person and you share air with that person for an appreciable at the time, and they've got something that they could infect you with.

Yes, there's a slim chance you could catch something.

But you gotta remember, out in the fresh air.

Aye.

There's a huge dilution effect anyway, be if that person's feeling like they got Corona virus, the chances are they're probably not gonna be pounding the pavement they're gonna be doing that Boris is doing and they're gonna actually be in bed because that's where we're told Use.

At the moment, we're told chances are they're not gonna be that infectious when they're out.

Yes, I know what you're gonna say.

I'm gonna.

But people might get symptomatic after they've already got the infection.

And after the already shedding virus, that may be true up to a point.

But what we do know is that the longer the infection goes on, so the maximum peak of the symptoms the infectivity rises.

So therefore, someone who's not feeling very unwell is they may well have virus recoverable, but they're probably not that infectious.

So the chances of you encountering a runner who breathes enough virus on you for you to pick it up in the fresh, open air of very, very slight, so I wouldn't worry about it.

I would I would concentrate more on the enormous benefit you're doing to your health through getting some fresh air, sunshine and exercise.

And the advice to runners would be be polite.

Train state two meters away.

Yeah, that's right.

Exactly.

Okay, here's one from Tim Sands in Ross on Wye on in Hereford.

Shit, Elisabetta, Who says if the number of tests being conducted rises logically, will the number of confirmed cases rise equally?

Why is so much important given to the data?

I think up.

Yes, we've just heard that there is a possibility of all isn't dramatic, a patience and that for testing, you know, in a surveillance.

Accepting.

So without asking if people have symptoms or not, we'll actually be able Thio, give us that number's about who is has got the virus even if they're there.

Well but also a testing generally, not only the people who are presenting coming with this most severe symptoms of requiring hospitalizations or the health care workers, but also testing more widely in the community will allow us to discriminated to identify who has the Corona virus and who hasn't and therefore no only we will have a much more accurate idea.

A picture off how much viruses circulating.

But there is the potential that we could start targeting for example, self isolation to only the people who we know are infected.

So increasing the number of tests would be, You know, the one sent to determine if you're having ongoing infections is extremely invaluable.

I'm interested.

Just maybe you could both give me an answer this Do you think antibody testing is more important than Auntie Jen?

Or is it more important to isolate people who are sick?

Is that is that the most important?

As faras you're both concerned, Crispin.

Well, I think they're two slightly different things that answer to slightly different questions.

At the moment.

Antibody testing isn't very useful, and that's because very few people have actually had the virus in the grand scheme of things so far, because you make antibodies and you make antibodies in appreciable amounts about three or four weeks after you cleared the virus.

So actually, at the moment, as we haven't had a very large number of people who have actively been infected.

We wouldn't be testing very many people in returning positive.

So antibody tests.

We've actually got time to wait a little while before they become useful and they will be very useful.

We're definitely gonna want them.

But what we need to focus on right now is telling people whether or not they really have this virus.

And the people we need to prioritize are the health care workers.

Because something like one in four doctors and about one in five nurses they're currently affected.

They can't actually get to their jobs or go to their jobs because they're self quarantining because they might have this infection.

They probably don't have this infection.

They probably have something else, because at the time they would have been catching it.

We know that from the test, we're doing an alibi or a tree.

Only a few probably about 10% of the test we were doing were actually positive for Corona bars in the last week or so.

That's really changed, though.

In the last week we've gone from small numbers of tests positive to maybe now half the tests were doing returning positive, so the numbers in the community really have leapt up.

But that's why it's now getting really valuable to be up to test people who have the symptoms to see who really doesn't who doesn't have it because that will inform who can come to work or not.

And look after the people who really do have it.

Okay, it is better.

Do they fumigate the roads in Italy?

No, did I am aware.

Okay, because this next question sort of lost on me.

I was nowhere.

Any country was doing that.

But KP from London Oh, I'm being told that China do this.

KP from London says My question is, why aren't the government fumigating roads with disinfectant sprays, like other countries are doing to prevent the spread of the Corona virus?

Uh, I think it's, uh yeah, so I So I think it's gonna get because he's actually disinfecting and and I think when there is a largest circulation off Oh, a virus that wild in the in the community.

Potentially, it is the scene, as it is acute Public health measure an intervention.

I would have thought, however, that actually social, distancing self isolation and cleaning those surfaces where we do actually come in contact because we touched the wound on our hands like handles.

Or, you know, if we have thio on public transport for examples or trolleys at supermarkets duels actually under the surface is we need Thio specifically, Look at I'm not sure how much, actually is infecting an entire road on the tyre mark, but I do have to admit that I tend to look.

A virus is from the molecular point of view, not when they are on Thomas.

Okay, all right, here's one Chris.

Which is it?

It's puzzle May actually, from Edward Picked in.

How long is the average time from contracting Cave Cave in 19 to death actually occurring.

And therein lies the rub with why this is proving such a challenge to tackle because it's a long time.

Unlike the flu, where you get symptoms almost from one day after you get the virus, and then within five days you've done and dusted the whole thing's over this thing.

It's only just getting going by five days, so the average incubation time before people even have any symptoms is five days.

It may be a cz long as 11 days we're using 14 days as a safety factor and then, having actually started to get symptoms, people then usually go along for about a week or so, feeling non specifically on.

Well, maybe they're cough gets a bit worse.

They have fevers, and they feel not very well at all.