Thread by @darokun

So, a little bit of what happened here:

The info was given by a multidisciplinary group of physicians and scientists at the hospital where I work (University Hospital of Munich).

The target group were hospital employees. I’ll summarize some of this info for the general public:

https://twitter.com/darokun/status/1235912141498134530

They showed a quick recap of how COVID-19 (the disease) started and how the virus (SARS-CoV-2) has been spreading.

SARS-CoV-2 is a common virus in animals. It is rarely transmitted to humans. The main alarm is because we don’t know how the virus behaves in humans (yet).

For the past ~2 months after the first case in China, we now know that there have been some acute transmission waves, and that the virus causes respiratory symptoms (similar to a common cold). The majority of the affected quickly recover.

The groups at risk of developing a severe disease are older adults, small children, and people with a weak inmune system. If you are a healthy young adult, chances are you’ll be fine.

We know this based on the lethality [rate] (which is *not* the same as the mortality [rate])

The lethality is the number of deceased persons divided by the number of infected people. It becomes a rate when counted by unit of time. I’ll simplify it by avoiding time here.

Suppose that there are 10 people infected with the virus who also have symptoms, and one of them dies because of the disease.

The lethality is then: 1/10 = 10%.

But a lot of people are healthy and carry the virus (are infected) without having symptoms (are asymptomatic). If we were to count these people as well, the lethality drops.

Suppose we have 20 infected people, of which 10 have symptoms and 1 dies. The lethality is 1/20 = 5%

Based on this, the lethality of the SARS-CoV-2 is currently AT MOST ~2%, and this is highly dependent on age: the older the patient, the worse the prognosis.

Compared to other viruses:

- influenza’s lethality is highly variable because it depends on the season. It ranges from 0.1% to 7.2%.

- the Ebola virus is highly lethal. At least half of the infected die (lethality of 50-70%).

- SARS-CoV (2003), a cousin of the current SARS-CoV-2, had a lethality of almost 10%, and extremely dependent on old age.

Here we can see how, although the majority of infected people are young adults (green), the number of deaths increases with age (yellow).

Interestingly, men seem to be twice as affected as women. The reasons are not yet clarified.

The most affected country so far has been (unsurprisingly) China, followed by Iran and Italy in the third place.

Some numbers in Germany:

Up until 05.03.2020 at ~12:00 (noon) there were ~400 confirmed cases of COVID-19 in Germany, and no deaths.

Up until 06.03.2020 at ~7:00 (am) there were ~545 confirmed cases in Germany, out of which ~79 were in Bavaria, and no deaths.

Numbers are increasing rapidly because of the current wave and the proximity to Italy.

The Robert Koch Institut (the highest health authority in Germany) strongly recommends to avoid travels to affected regions in China, Iran, Italy and Nordrhein-Westfalen (in Germany). This is to avoid being exposed to the virus and bringing it back as a carrier or getting ill.

At the hospital, we’re also limiting visits of guest physicians, guest scientists and students. The recommendation now is to postpone these visits until further notice.

However, we are in general more worried about the impact of other diseases (e.g. influenza) than about COVID-19. Here’s a comparison of two seasonal waves of influenza, 2018/2019 in blue, and 2019/2020 in red, against COVID-19 in green, across calendar weeks.

So, what to do? And what do current prevention strategies mean?

There are two main public health approaches to deal with infectious diseases: Disease Containment Measures and Disease Mitigation Measures.

Here’s a nice thread by @MiceDoctor explaining what these are:

https://twitter.com/MiceDoctor/status/1233450895523885057

Now, if you:

- have respiratory symptoms AND are or have recently been to a high risk area for the virus: Go get yourself tested. Then, stay at home for at least 14 days.

- have respiratory symptoms but have NOT been to high risk areas: Stay at home but no need to get tested.

Preventing yourself and others from getting infected is as simple as general preventive measures against ANY respiratory infection:

- wash your hands thoroughly for at least 20 seconds or use an alcohol-based sanitizer.
- avoid touching your face with unwashed hands.

(General preventive measures continued)

- stay at home if sick.
- cover your mouth with your elbow or with a tissue when you sneeze or cough.
- clean and disinfect frequently touched objects and surfaces.

And if you’re a healthcare practitioner: follow the indications of your employer on how to use Personal Protective Equipment at work and what to do in case you’re sick.

For more info:

CDC: cdc.gov/coronavirus/20…
WHO: who.int/health-topics/…
RKI: rki.de/DE/Content/Inf…

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