# Corona – CoronaFuturum forecast calculator for the COVID-19 virus epidemic

We present the CoronaFuturum Forecast Calculator, a corona ticker for the course of the COVID-19 virus epidemic.

All models are wrong, but some are useful. (George Box)

## COVID calculator – short introduction

The spread of the COVID-19 virus develops an exponential function at times, in particular at the beginning.

So the first thing we asked ourselves was:

- “What is the course of COVID infection over the next 10 days?”
- “How can we tell if the measures to contain the COVID-10 virus epidemic are working?”

Consequently, we have mapped a country-specific PROJECTED curve for the natural course of the virus epidemic for each country. This is based on the country-specific initial curve and the associated transmission rate per infected person. We compare these with the actual number of cases and the ACTUAL curve to gain an impression of whether the measures taken to contain the epidemic are effective or not. You can find this data under “Adjustment of exponential function”.

Next we asked ourselves:

- “When will the maximum of the epidemic be reached”

For this purpose we have developed the SIR model for you.

In addition, you will find further interesting processing of the figures, which we update several times a day from official sources.

Our aim is to provide you with planning security for the medium-term future. Please note that this is a simple statistical adjustment. Accordingly, we do not say that the real case numbers will continue to follow an exponential function. Rather, we expect that the ACTUAL curve of the actual case numbers will deviate from the exponential PROJECTED numbers as the containment measures take effect (see also China).

The use of the COVID-19 calculator is at your own risk.

## Prediction of the COVID-19 virus epidemic – statistically representable?!

The COVID-19 virus infection is an inflammatory disease that spreads by contagion. Consequently, we assume that in the normal social community 2-3 more people are infected per virus carrier. Thus the COVID-19 virus infection follows mathematical laws. On this basis, we have created the CoronaFuturum Prognosis Calculator for you with a graphical representation of the disease over time, both for Germany and for other countries.

You have to make things as simple as possible. But not simpler. (Albert Einstein)

Prognosis in this case means that we can estimate the number of infected people relatively reliably over a limited period of up to 10 days in the future. The CoronaFuturum Forecast Calculator for the COVID-19 virus epidemic accesses the official figures of the epidemic on a daily basis and has so far proved to be surprisingly reliable.

In addition, by means of the deviation of the actual values from the statistical target value, we can obtain an indication of when the infection will be controlled by hygiene measures.

Without question, living with a potentially deadly virus epidemic is not easy. But we also know that this virus epidemic will come to an end. By thinking clearly and acting in a structured way by each of us in the context of social interaction, we ourselves can put an early end to the epidemic for all of us.

Our main goal is therefore to give you security in dealing with yourself and other people, so that you can plan your everyday life better.

A severe virus epidemic can only be controlled by the social action of every individual in the community. (Franz Imhäuser)

## CoronaFuturum prediction calculator – Why actually?

The prediction calculator answers 2 of our most important questions in the COVID-19 virus epidemic, which will have a significant influence on our behaviour in everyday life:

- How long will the COVID-19 epidemic last?
- When can we expect the COVID-19 virus epidemic to end?

*Duration of the virus epidemic*. As long as the course of the actual number of infection cases corresponds to the statistical target value, all hygiene measures, especially those of self-isolation of healthy persons, must be strictly adhered to.

*End of the virus epidemic*. If an end to the epidemic is in sight, then you must continue to follow the official guidelines on hygiene measures, because after all, these have led to success. However, you will be able to plan for an expected easing of the infection situation. This is particularly important for employees and employers.

## Corona Ticker – Spontaneous course of corona virus infection – exponential increase in cases of illness

If no countermeasures were taken during the COVID-19 epidemic, the number of people affected would increase exponentially. Exponential means a very steep increase in the number of cases per time.

An exponential increase in the number of cases of illness also means that the number of deaths may increase in absolute terms, but also in percentage terms. The mortality rate for a COVID-19 virus infection is 2.0-3.5% with optimal medical care.

The most common reason for death from a COVID-19 infection is severe pneumonia. Optimal medical care therefore means above all that sufficient intensive care beds with the possibility of artificial respiration are available. If not enough ventilation places are available, the mortality rate from a COVID-19 virus infection increases.

In short, if the intensive care unit capacities are fully utilized and all ventilation places are occupied, a critical care situation with an increase in mortality occurs. This is the real problem of the COVID-19 virus epidemic.

## Corona Ticker – Preventive measures in case of corona virus infection – Flattening of the exponential curve

Experts assume a viral infection with COVID-19 in 60-70% of the German population. The vast majority of cases, i.e. about 80-85%, will proceed in such a way that a hospital stay will not be necessary. However, 15-20% of the cases will be severe, so that a hospital stay up to intensive medical care may be necessary.

In order that not all people are infected within a narrow time window, the simultaneous infection of many people must be prevented above all by measures of self-isolation of healthy people. This would mean a flattening of the exponential curve described above. As a result, the medical system would have sufficient capacity to care for all patients; mortality would be “only” 2.0-3.5%.

If we do not succeed in flattening the actual curve together, then a significantly higher mortality of the COVID-19 epidemic can be expected.

## Corona -What is exponential growth?

Exponential growth cannot be understood intuitively. We humans think linear, i.e. we think that changes continuously increase or decrease at the same rate. With exponential change the speed increases or decreases with time. Exponential means slow in the beginning and then faster and faster.

In short, imagine we put a virus into an empty jar at 11 o’clock and it multiplies every minute (jar 1). So at 11:01h we have two viruses in the glass (glass in the middle) and still a lot of space. One minute later there are already four viruses, then eight, then 16, then 32, and now just five minutes have passed.

If we come back at 11:59h and look at our glass, it is only half full (glass on the right). One could think there is still a lot of time. But already one minute later, at 12:00h the glass is full! For 59 minutes it looked like there was still a lot of space and time. In retrospect, however, you can clearly see the exponential growth (curve below).

## Corona virus epidemic – exponential growth vs. cure?

How is this situation applicable to Covid-19? Well, we don’t know when the glass is gonna be full. But we can estimate how soon the virus will double in size. Consider the example of China in the following graph.

The dotted line is the total number of cases, the green bar the “healed” and the black one the deceased. You can clearly see that the dotted line falls away and deviates far away from the estimated exponential red line. China no longer seems to have exponential growth.

Finally, the purple line (healing quotient) shows on the right axis the percentage of those who had the virus in relation to the total number. The higher this value the healthier the population.

Now the red prediction curve here goes further than the date of the case numbers. We can make a prediction about the coming cases as long as we are on the “target” curve. In the title, the quality of the estimate (R²) is given, the higher this value (maximum 100%), the better an exponential function fits to the case numbers.

Consequently, this is merely the modelling of an exponential model and not an epidemiological simulation. However, since the daily reported case numbers are only a glance in the rear-view mirror, with an average incubation period of five days and a test duration of about two days, the number of currently infected persons is more likely to be read off the prediction curve in one week.

Do what you can with what you have, where you are (Theodore Roosevelt)

## Corona Ticker – Measures to limit the COVID-19 virus epidemic

The most important measure to control a severe virus epidemic is, besides hand hygiene, the self-isolation of (supposedly healthy) people. Be a role model in your social environment.

In addition to reducing the infection rate, you also show social responsibility for your social environment. Consequently, it does not make sense for everyone in a social cluster to become ill at the same time. After all, the healthy have to provide the sick with food.

Be a constructive member in your social community and set a good example.

You do not lead by showing people and telling them where to go. You lead by going to that place and making a stand. (Ken Kesey)

### Corona Ticker – Click here for the CoronaFuturum forecasting calculator

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