It's no big deal in Asia.

They've been doing it long before the coronavirus pandemic.

Western countries have been more reluctant to adopt face masks as a useful tool to fight the virus way.

Don't generally recommend the wearing of masks in public by otherwise, well, individuals because it has not been up to now associated with any particular benefit.

But eventually, opinion changed fancy home.

Soon, masks popped up everywhere and experts changed their tune, People congregating often without masks, of being in crowds and jumping over and avoiding and not paying attention to the guidelines that we very carefully put out.

We're going to continue to be in a lot of trouble, and there's gonna be a lot of hurt if that does not stop.

A small variants of the virus emerged.

Medical masks were back on the agenda, even becoming mandatory in some places.

But can masks really beat the virus?

That's the question.

Well, counter are covered.

19 special.

I'm Monica Jones in Berlin.

Good to have you with us.

And just in case you're wondering, why isn't she wearing a mask?

Well, the studio is pretty much the only place I can take it off for now because things keep changing, just like the virus itself.

And that also goes for the acceptance off wearing masks on the evidence that they really help curb the spread off the virus.

In fact, a study from Germany has found that facemask could reduce the number of new Kobe 19 infections 20 days after their mandatory introductions, anywhere from 15 to 75%.

Researchers also found that the reduction in new cases was the most for those above 60 years of age.

This is the first study to identify causal effects in a population rather than in a clinical setting, highlighting the correlation between wearing face masks on a drop in new infections.

Classified, a professor of economics at the Johannes Gutenberg University minds is the co author off this study, and he joins me now, Good to have you with us.

Uh, what I noticed is that your study doesn't mention specific facemasks.

Why not now?

That's true.

We don't mention specific facemask because the regulation at that time just required to wear any mask.

So these were probably normal, self made homemade masks.

Okay, so we don't really know about the efficacy when we take into consideration the medical masks, which are now mandatory in many places or FFP mask?

Or do you have a hunch?

Would there be even more effective?

Well, yes, of course.

I mean, there are other studies that study in detail Which type of mask is for effective.

And we know, of course, that, uh, lost masks are not the best one.

So f f p to mask as an example, they have a much better filtering system.

Okay, but apart from the model or the material off a face mask, what other factors play a role in in making wearing a mask?

Effective?

I believe your study also points to different regions.

Different climate.

Yeah, well, regions and climate.

I'm not so sure, but But what definitely matters is how good a mask fits.

So if a za manu where Ah, beard, then Of course, there's a lot off airflow at the edge of the mask, and this can be a problem.

And in any case, with any mask, it depends on the environment.

If you are in a, uh, contaminated, uh, if you inhale contaminated ambient air, then you can get infected anyway.

I mean, droplets and very small droplets.

They enter anyway, right?

I just had to smile because you mentioned beards.

And I know a few colleagues here, including our science correspondent, who will find it difficult to part with the beard.

But back to the efficacy of a face mask.

The average in your study says it's that around 45 47% that's a good start.

But it means that we also need different measures to win this fight.

Which rules are the most important?

Are all the rules that we need in place from your point of view?

Well, it's definitely true.

Mask are not the only measure we should employ.

There should be other rules.

But if I should say something about rules, I mean, rules are one thing, but compliance to rules.

It's a much different things.

When we look, for example, at the sudden increase off infections before Christmas, then we This cannot be related to rules because the rules didn't change at that time.

But we know from ability data that around Christmas, which can be understood but nevertheless, around Christmas, mobility increased a lot, so the question is, how much compliance is there, Thio rules in the private environment.

And then another issue is, for example, the masks at workplace.

I recently went to a small enterprise for mechanical repairs.

Uh, and everybody was without mask.

I mean, I was shocked.

I mean, so mask at the workplace.

They would all That would be a good measure as well.

Exactly.

And you just mentioned statistics with looking at mobility before Christmas.

I mean, we've we've been flooded with statistics on daily infection numbers.

Now for almost a year now on.

More recently, sadly, we also get the daily death numbers.

But how helpful are those statistics when it comes to assessing the situation?

Right now, Yeah.

This is a very important question.

The daily reported infection numbers we hear every day they have serious statistical problems.

There's a systematic bias.

Where does this bias come from?

Well, we test for different reasons.

One example is we test when people go to a doctor and have symptoms, and then we test the individuals who had contact with the person who is infected or we test individuals that return from holidays.

The statistical problem resulting from this is when the relative importance off how many tests you undertake because of symptoms or because of travelers or because of other reasons.

When this relative share changes, then the reported number of infections are not comparable over time.

Um, there are, of course, other statistics which are less biased when we think about the number of individuals in intensive care units.

I mean, this is definitely very unbiased.

This is a very good measure.

And then, as you said, the number of deaths you don't want to hear this, but this is also unbiased measure, but unfortunately, these measures are delayed.

No, I mean, this is not, uh, instantaneous.

Measure off how severe pandemic is.

So what we should do is we should not just test individuals.

I mean, testing is extremely important test as much as possible.

But we should also report why individuals were tested.

And if we knew, for example, all the positive tests off individuals that were tested because they had symptoms, then we should.

Then we would count covert 19 cases, so cases off the disease and this would be an unbiased measure off the severity off the pandemic.

Okay, so there is definitely some homework to be done.

Certainly when it comes to effective testing.

Just very briefly.

At what point do you think?

Can we been our masks?

Uh, well, when the pandemic is over, Simple answer.

Okay, if if if I had to give a rule, um, wait for the number of patients in intensive care units to fall to a level that we had in spring 2020 then we can be more relaxed.

So we need to use unbiased measures.

And on this, we can based long term rules and long term planning.

All right, that sounds like a good plan.

Class Veda, professor of economics of Johannes Gutenberg University minds and co author of the study on Facemasks.

Thank you so much.

You're welcome.

So testing and wearing face masks to reduce the number of infections That's half the battle won.

But some cases are less easy to trace than others.

Which brings us to one of your questions and over to our science correspondent, Derek Williams.

What do estimates now say about the percentage of infections caused by asymptomatic cases?

To answer this, we have to first look at differences and similarities in asymptomatic and pre symptomatic carriers of Cove in 19.

Now, if someone is infected with the virus.

It might take time to develop symptoms, but most people eventually do.

They're just pre symptomatic for a while.

One of the things that's made this disease so hard to combat is that, unlike, for example, people who got SARS, we think Cove in 19 patients grow most contagious late in their incubation period.

So so while the virus is reproducing rapidly but before they begin to show symptoms for some reason, truly asymptomatic people never developed symptoms but apparently go through a similar stage of shedding the virus.

What asymptomatic and pre symptomatic people have in common are those few days where both are carrying the virus and shedding it.

Yet neither is showing any sign of disease.

So maybe we should instead ask how many people are getting Covad, 19 from people who aren't showing any symptoms?

A recent study published by CDC specialists tried toe answer that question.

The researchers had to make a couple of educated guesses, but based on data from other studies, they assumed that close to a third of all people who catch the virus remain truly asymptomatic and that they're around 75% as infectious as those with full blown disease.

If those baseline assumptions are correct, asymptomatic people would be responsible for around a quarter of all cove in 19 infections.

Pre symptomatic transmitters are thought to pass it along at even higher rates than that.

So the model therefore predicts over half of all cases of Cove in 19 are transmitted by people who have no symptoms at the time they transmit it.

No wonder tracing infection chains has proven so difficult.

It's more support for the advice that that wearing masks in public is a good idea, even if no one around you is coughing.

Which brings us back to the topic off this program.

That was Derrick Williams, of course, and he'll be back to answer more of your questions again tomorrow.

That's all for this edition off Kobe 19 Special.

But as we're all staffed of arts and culture in these trying times, we want to leave you with some images from eternal Rome, from the Coliseum to the Vatican Museum, which you can visit again with a face mask.

Of course, enjoy the views.