Corona: how Germany could live with the virus in the long term

We have to learn to live with the coronavirus. The ruling comes up time and again in the Sars-CoV-2 pandemic, only the question of how exactly this could be successful has thus far been largely unanswered.

Researchers working with physicist Viola Priesemann from the Max Planck Institute for Dynamics and Self-Organization took a closer look at two concepts and calculated what they would mean for each individual and the long-term course of the pandemic.

Two long-term options

Priesemann specializes in simulating propagation processes, such as that of viruses. “No vaccine has yet been approved and it will take time to distribute the vaccine to the population,” he said Wednesday in an interview with reporters. “So now we have to think about what strategy makes sense for the next few months.”

Two concepts in particular are discussed: it is conceivable to focus on keeping the number of infections and ultimately the number of patients who must be treated in intensive care units below the capacity limit of clinics. The alternative would be to keep pushing the numbers to the point where reliable contact tracking is possible.

The calculations made by Priesemann’s team point in a clear direction: once the number of new infections has dropped to around a thousand a day, people would only have to restrict their contacts a little to contain the virus in the long term, informs. the explorers. Restaurants and cafes could reopen with hygiene concepts.

On the other hand, the constant high number of infections meant important sustained restrictions in order to avoid overcrowding in intensive care units. At the same time, there would be more sick and more dead.

Less sick, less dead, more freedom

When the number of cases is low, preventing 40 percent of infections is enough to stabilize the spread of the virus and prevent a new closure at the national level, the researchers write in their previously published study.

Since infections arise through contact, this means that people also have to reduce encounters with other people by 40 percent compared to the time before the pandemic. According to the scientists, this can already be achieved by relatively mild contact restrictions.

According to one study, limiting the number of participants in major events to 100 people would mean that there would be about 35 percent fewer infections in the population. If you reduce the group size to less than ten, you will achieve a reduction of about 45 percent. Frequent ventilation, keeping your distance, and wearing a mask can also reduce the risk of infection, so more contact would otherwise be possible.

“In this scenario, people would only have to give up relatively few contacts and would otherwise have great freedom,” Priesemann said. At the same time, the number of sick people and therefore deaths would be significantly reduced. The economic consequences would also be less if catering establishments could be reopened.

One last difficult close

However, a permanent closure would be necessary to reduce the number until such time that the virus can be controlled again. “Currently there are so many infected people that health authorities cannot identify and isolate infected people before they infect others,” Priesemann said.

Also, about ten percent of the tests performed are positive. This high value is a clear indication that the testing capabilities are not sufficient to verify all unfounded suspected cases and therefore more. “That means there are a lot of unreported cases and with it many chains of infection that cannot be contained at all.”

Therefore, the goal should be to push the R-value back below 0.7, as was the case in the first wave, according to the researcher. This could reduce the number of infections by at least half each week. “Just as we see exponential growth with a value of R above one, the numbers decrease exponentially with a value of R below one.”

The effect is reinforced by the fact that fewer cases are missed with fewer infections. If there are few new infections, rapid tests could also make it easier to control the infection process in the future, Priesemann explained.

Protection against excessive spread at Christmas

If, with the help of the measures now decided by the heads of state of the federal states and Chancellor Angela Merkel, the number of infections could be reduced by an additional 30 percent, the number of new infections in the period of December 1 a Christmas could be reduced to around 2,500 – and then it would be relatively easy to control.

One more week could reduce the value to around a thousand. In order to do this before Christmas, around a third of current infections should be avoided from now on.

“Christmas parties with ten people from different households and their children, as well as New Year’s Eve celebrations with a low number of infections with regular ventilation, could easily be justified,” says Priesemann.

The probability of encountering an infected person in one of these events is low under the conditions mentioned. Also, chains of infection that started over the holidays could contain more easily (read more about this here).

If the infection situation were to get out of control again in one region, countermeasures would have to be taken quickly in a small area. Infections that would be brought in from neighboring countries could, to some extent, be contained through contact tracing, Priesemann said. “The best would be a uniform strategy with the clear objective of reducing the number of cases in Europe.”

Significantly reduce long-term contacts

The alternative concept of reducing the number of infections enough so that intensive care capacities are sufficient would mean, according to the study, maintaining the current situation more or less permanently. From time to time, hospitals are already reporting overloads. There are still possibilities to switch to other clinics, but the scope is getting smaller.

“The restrictions of the last few weeks have caused the R-value to fall from around 1.4 to around one,” Priesemann explained. This means that each infected person is currently infecting another person on average.

“If we maintain the degree of contact reduction as in the current partial closure, the number of new daily infections will remain at around 20,000,” says the expert. The numbers would rise again through easing.

According to the researchers’ calculations, if the incidence is high, infections and therefore contacts should be permanently reduced by about 60 percent compared to the time before the pandemic; otherwise, nationwide closure measures would be necessary repeatedly.

While four out of ten infections, and therefore contacts would have to be removed with a low number of infections, here are six out of ten.

»The 40 percent reduction in contact in the low-incidence scenario can be achieved almost only by avoiding large events and larger gatherings and through hygiene measures. Giving up an additional 20 percent of contacts makes it necessary to cancel significantly smaller meetings as well, and even that might be enough, ”Priesemann explained.

A communication problem

The secondary effects of this strategy would be, in addition to the permanently stronger contact restrictions, a greater number of illnesses and deaths and, therefore, a greater burden for the health system, as well as for tens of thousands of people permanently in quarantine.

“That is also a disadvantage for the economy,” Priesemann said. Furthermore, the strategy is riskier, as the long-term consequences of a Sars-CoV-2 infection are still largely unknown.