Thread by @slowblogger

Key indicator on #COVID19 is active cases, the number of patients who are currently sick. In most countries, this is increasing fast. One country that is showing decrease is South Korea.

If all countries looked same, it would be great. Right?
#Masks4All 1/18

Compare the curve. Korea and Italy. Similar population size, and vastly different trajectories so far.

Note also that the Italian axix is 10 times as high as the Korean.

By the way, the US looks even worse right now. 2/18

The main driver of active cases is new cases. If you have increasing new cases, the healthcare systems will be unable to treat them fast enough.

The first real burst came around Feb 19, and it peaked at 851 on Mar/3. Then it dropped fast. Now it is stable around 100. 3/18

Italy looks very different.

Italy started lock down of some towns in Lombardy on Feb 23. So it seems the panic happened at similar times.

New cases kept growing. Its peak was 6,557 on Mar 21. And the number did not go down quickly. That made 10x difference in active cases. 4/18

So what made the difference? International media talked about Korea's aggressive testing and tracing.

nytimes.com/2020/03/23/wor…

bbc.com/news/world-asi…

They were not seeing the elephant in the room. 5/18

I also became really worried about the world. Korea still needs to solve the issue. But even if it did it, the world needs to.

Korea happens to be a good case study. So what was the difference? 6/18

Life in Korea has been quite normal.

Schools are delaying opening dates. Many churches are giving services online. Some companies worked online.

But other than that it is not that different. Most surprisingly, subway is still crowded during rush hours. 7/18

Social distancing is done everywhere.
Intl travel control is loose. Even dangerously.
Healthcare is working hard. Same everywhere.

Testing and tracing? Can they trace everyone who took the same subway? Many tests were done, yet less than 1% of pop. 8/18

The only thing that is really different was the mask. From two angles.

1. From European countries and the US
2. From Korea itself until mid February

medium.com/@slowblogger/t… 9/18

Not many Koreans wear masks in normal time. When the air quality is bad, 10-20% may wear masks. I am not one of them.

After the virus was known in January, many began wearing masks but probably not more than 50-50 until mid February based on what I saw on the subway. 10/18

From February 19 or so, things changed quickly. New cases burst and doubled for a few days. And I could see almost all people with masks on the subway.

It was chaotic at first due to shortage. A week or two of chaos, and now you are allowed to buy 2 masks per week. 11/18

The mask rush began about Feb 20. And new cases started going down after Mar 3.

There can be latency as long as 2 weeks (some say even longer), which might explain the delayed effect.

The timing could have been different, I know, even if you accepted the mask caused it. 12/18

I looked for photos from the US and Europe. Some were wearing masks, but not many. Even in subways. I even asked someone in Europe.

Mask wearing was 20-30% at most. 13/18

Is there any scientific proof? The answer is yes. Copying from my post,

"the intervention effect of wearing a mask was 68%, ... larger than that of washing hands over 10 times daily."

68% less risky if you wear a normal (no-filter) mask

medium.com/@slowblogger/t… 14/18

There is an even more solidifying study. A research of Chinese hospitals treating Coronavirus in Jan this year.

"none of the 278 staff in the N95 group became infected, but 10 of 213 staff from the no-mask group were confirmed as infected."

N95 mask protected perfectly. 15/18

People also worry about the economy. For ordinary people, it means making a living. It's serious.

I believe we should be careful, but some people may want to go back to normal life earlier.

For them, mask can be a minimum requirement. 16/18

I am writing this at a cafe in Seoul. There are many people. No one is wearing a mask.

Koreans wear masks on subway, on street, at stores, but not at cafes. Neither at offices, it seems.

Pretty loose, right? Perhaps wearing masks on public transport was key. 17/18

Now Czech shows sign of success. Austria on board.

@WHO: "Masks should be worn by those with the disease or those in close contact with those infected."

Do you know if you or ones around are infected?

Wear the mask! #Masks4All 18/18