display

The federal and state governments want to discuss the further strategy in the corona pandemic on February 10th.

What distinguishes this meeting from the talks in December and January: A seven-day incidence of 50 new infections per 100,000 inhabitants, which politicians have declared the gold standard, could soon be achieved.

Simulations by Saarland University show that on February 18, an incidence of 50 could occur across Germany.

Thorsten Lehr, Professor of Clinical Pharmacy, and his team have calculated the possible course of the pandemic in a Covid-19 model using data from the Robert Koch Institute (RKI), the Divi Intensive Care Register, health ministries and hospitals.

In this way, Lehr is advising, among others, the Saarland Prime Minister Tobias Hans (CDU).

In a previous panel of experts, Chancellor Angela Merkel (CDU) consulted a similar model from the TU Braunschweig.

According to Lehr, the fact that Germany will reach the threshold of 50 new infections per 100,000 inhabitants is due to the lockdown since mid-December.

According to his calculations, which may differ slightly from those of the RKI, the measures reduced the reproduction value to currently 0.78.

Ten infected people infect fewer than eight other people on average.

However, the infection rate is developing differently in the individual federal states.

The Covid-19 model by Thorsten Lehr and his team shows when an incidence of 50 (35) would be reached in which federal state.

Bremen and the Saarland deviate from the federal trend

Source: WORLD infographic

display

"We have a three-part infection process in Germany," says Lehr.

Berlin, Brandenburg, Saxony, Saxony-Anhalt and Thuringia, which recorded above-average numbers of new infections in December and January, have below-average reproduction rates with values ​​between 0.6 and 0.7.

With R values ​​around 1, Bremen and Saarland are not only above the national average, but also at a level at which the virus is spreading.

The other countries are in the middle.

Lehr can only speculate about the reasons, since in most cases it is still not clear where the infected are infected.

"East Germany had a lot of deaths," says Lehr.

“It is possible that the measures will be enforced more strongly or that the population will be more involved.

Bremen and Saarland never had an incidence like Saxony, that can have a psychological effect. ”And unlike Saxony, Saarland has not yet carried out any checks on commuters.

"In Saarland, the R-value will not stay above average, because politics and authorities will try to react," he predicts.

The different R values ​​also have an impact on the question of when a 50s incidence can be reached.

This mark could fall first in Baden-Württemberg (February 12), followed by Berlin (February 13) and Lower Saxony (February 14).

Saxony-Anhalt (February 24), Thuringia (February 27) and Hamburg (February 28) would have to wait longer.

In Bremen (April 10) and Saarland, which, according to Lehr, could not achieve this incidence without additional measures such as commuter controls, politicians would have to readjust again.

35, 25 or 10 - other limit values ​​are also being discussed

display

In the run-up to the Prime Minister's Conference, there is also talk of extending the lockdown even if the incidence is below 50.

Several federal states had already decreed in autumn that from an incidence of 35 new infections per 100,000 inhabitants within seven days, stricter restrictions apply, in Bavaria, for example, stricter mask requirements and contact restrictions.

The SPD health politician Karl Lauterbach had only proposed easing from a seven-day incidence of less than 25.

And a concept of the “No Covid” initiative, in which the virologist Melanie Brinkmann and the economist Clemens Fuest are involved, only holds out the prospect of easing if the incidence is less than ten.

Throughout Germany, a seven-day incidence of 50 could be reached on February 18, if the mutation does not favor the spread again

Source: WORLD infographic

According to the Covid-19 model, an incidence of 35 would have been reached in Germany on February 28 - provided the measures remained in force as before, were adhered to and monitored.

"Openings will lead to an increase in incidence relatively quickly," says Lehr.

"As long as not enough citizens have been vaccinated, I think easing it is difficult." In the data, there is a tipping point at 20 new infections per 100,000 inhabitants within a week, explains Lehr.

After that, the R-value increases sharply, as last at the end of September.

This is an awkward position for politics.

From a purely epidemiological perspective, lifting the restriction would not be necessary if the incidence is below 50 new infections per 100,000 inhabitants.

At the same time, the federal and state governments have repeatedly promised easing above this value.

Lehr knows that too.

"There are expectations that politicians have to meet, even if it could potentially lead to a third wave."

British mutation leads to a higher rate of reproduction

display

Worrying virus mutations are making it even more difficult for the Prime Minister's Conference to decide to relax.

Research from the UK shows that the British variant could be 56 percent more contagious.

If B.1.1.7 is more widespread in Germany, the R value threatens to rise from the current 0.78 to 1.22 despite measures.

The virus would continue to spread again.

However, it is unclear how infected Germany is with the British or South African variants.

By January 31, 168 records of B.1.1.7 were reported to the RKI nationwide.

The South African mutant B.1.351 has been detected 27 times.

According to the RKI, studies of over 30,000 positive Sars-CoV-2 samples in the last week of January suggest a B.1.1.7 share of just under six percent - and the trend is rising.

Lehr has modeled two scenarios: if the British variant is two percent widespread, Germany could remain below an incidence of 50 until May.

If it is ten percent widespread, the 50 mark would be affected in March, then the number of new infections would rise again.

“The mutation could be responsible for a large number of infections in a very short time,” says Lehr.

Thorsten Lehr and his team compare the predicted new infections with the actually reported cases in order to assess the quality of the model

Source: WORLD infographic

Lehr compares his Covid-19 model with other forecasts such as the weather forecast.

Slight differences, such as the method for calculating the R-values, led to similar, but not identical, results compared to other Covid-19 models.

To check this, Lehr compares the prognoses with the corona infections and hospitalizations that have actually occurred.

In fact, in December, his model predicted a dent in the seven-day incidence and the number of new infections after the holidays - albeit not in the clarity that actually occurred, which was partly due to the delay in reporting by the health authorities.

“A model is not the prognosis of the redemption from the pandemic,” says Lehr about his work.

“It helps to steer through a fog and run through what-if scenarios.

That's a big advantage."