It’s not fun to sit at home all day. Movement and fresh air are missing, the children go crazy – in the worst case, boredom and gloom alternate. How many days or weeks should this go on? When is the corona spook finally over?

This is not just a question for all people who are now more or less under house arrest. Many companies are on the verge of ruin because the work is reduced, customers no longer come or the business is completely shut down.

How long this lockdown lasts depends primarily on how consistently it is implemented. This is shown by pandemic models – such as that by researchers from the University of Basel or that of the programmer Gabriel Goh. It is paradoxical: the better we contain the erratic spread of the coronavirus, the longer we have to submit to restrictive measures. Because then the curve of new infections will be flatter, but the virus will be rampant in Germany much longer.

These model calculations are subject to various uncertainties. However, one thing is clear: if neither medication nor vaccination is available in the coming months, the lockdown could, in extreme cases, continue until 2021 – a grim forecast.

The following three scenarios use Germany as an example to show how the number of infected people could develop, depending on how restrictive the measures taken are. This was used Model by Richard Neher and his colleagues from the University of Basel.

All simulations start on March 1st, 2020 with around 1700 infected people and run for one year. The calculations also take into account the treatment capacities of the hospitals. For example, if there are more seriously ill patients than ventilation places, the death rate increases. The model assumes that on average around one percent of all Covid 19 cases end in death and takes into account that mortality increases with age.

**Scenario 1: Unchecked outbreak**

No protective measures are taken in the first scenario. If you count every day how many people are infected in Germany that day, you would come **middle of May **to the maximum of** 22.5 million people**. By the beginning of July, this number would quickly drop back to below 100,000.

*The following diagrams use a logarithmic scale. The distance between 1 and 10 is the same as between 10 and 100 or between one million and ten million. This means that you can oversee the relatively small number of beds and severe illnesses and the number of infected people, which is sometimes up to ten orders of magnitude higher. *

In this scenario, the corona crisis would be over the fastest – but at a price that nobody wants to pay. According to the model calculation, up to 500,000 people would need intensive medical care at the same time. However, there are not even 30,000 so-called ICU places in Germany. As a result, more than 700,000 people could die within a few months. More than 70 million Germans had been infected with the corona virus in the months to summer and then survived the infection.

**Scenario 2: Braked outbreak**

Flatten the curve – flattening the rise in the number of infected people: this has been the watchword for days. This is exactly what is done in the second scenario – but only with moderate interventions. The researchers are reducing the infection from person to person. According to the model assumptions, an infected person infects 2.7 people on average without protective measures. If this value can be reduced, the curve of the detected new infections becomes flatter.

In the “Moderate” scenario, the transmission rate drops by about a third from March 1 to May 1 and then remains at this value. An infected person therefore infects far fewer people than without protective measures. As a result, the peak of the infected curve shifts back into June by about a month. Instead of 22 million there are only **almost 8 million infected at the same time**. In September, the daily infected numbers would then drop below the value of 100,000.

Although the curve is much flatter, the health system would collapse here as well. At its peak, more than 200,000 people would need intensive medical care at the same time – almost ten times as many as there are places. According to the simulation, there would be around 500,000 deaths.

**Scenario 3: Flat curve**

In the third scenario, the infection curve is flattened so much that the number of seriously ill people always remains smaller than the number of places in intensive care units – in the model this is 24,000.

We ran the scenario for one year from March 1, 2020. The number of infected people will therefore only peak in January 2021 – **at around 450,000**. According to the model calculations, the daily number of patients classified as seriously ill on this day would be a maximum of 15,000. If the number of places in intensive care units is increased in the coming months, the hospitals could cope with this – and at the same time provide intensive care to all other patients who are not affected by Covid-19.

According to the calculations, the death toll would be just under 100,000 by March 1, 2021. Still terrifying – but significantly less than in the other two model calculations.

However, this scenario has a serious disadvantage: It takes a long time for the situation to relax again. It would not be that far in January 2021, nor in March 2021. And protective measures would have to be maintained throughout this period.

“As long as a large part of the population is not infected, the restrictions are necessary to prevent the number of cases from rising again,” says Richard Neher, a researcher from Basel. A “long defense battle” would have to be carried out to prevent repeated outbreaks. Or as the virologist Christian Drosten put it: the fight against the virus is “not a sprint, but a marathon”.

The protective measures in Germany may not have to be as drastic as in China. Apparently it has succeeded there to reduce the number of new infections to zero. The third scenario does not go that far. The question is which measures work how well and which one can possibly be dispensed with. This will be shown, among other things, by the number of people infected in the next few weeks.

**There is hope! **

The prospect of half a year or a year of lockdown will scare many – but it doesn’t have to be that way. The researchers simply do not yet know enough about the virus and its spread to be able to make a reliable statement. This is why some of the parameters of the models may prove to be too pessimistic – and the results of the model calculations prove to be an exaggeration.

It could turn out that the number of undetected infected people is much larger than expected. If, as a study suggests, there were ten times more cases than in the current statistics, the mortality rate would be much lower. A high number of infected people would then be less dangerous for the health system.

With the model of the programmer Gabriel Goh For example, you can set mortality from 1.0 percent to 0.1 percent – and start the simulation with 5000 infected people instead of 500. If one chooses moderate measures, there would not be almost 500,000 deaths in the first 200 days, but only 50,000.

But the greatest hope rests on the researchers who are working intensively on medicines and vaccines. The sooner these are available, the sooner the corona crisis is over. With a widely available active ingredient that directly helps the seriously ill, the protective measures could possibly be reduced quickly.

“I am very optimistic that there will be a vaccine in the next twelve months,” says Richard Neher. It is possible that some measures could be relaxed in the future if one consistently tests, retraces and isolates contacts.

There is a difficult time ahead of the people, says the researcher. “But I think it is possible to contain the virus. China, South Korea and Singapore show that.”