Science

School openings could lead to a drastic increase in infections

The schools in Germany are reopening these days, gradually for the older students, then for younger age groups. In the shortest possible time, countries, cities, municipalities and every school are required to draw up hygiene plans and distance rules for teachers and students.

But can children and young adults be educated from a distance? Can social distancing suddenly be implemented in places where there is otherwise exchange and social closeness? And what are the consequences for the course of the epidemic? It is known from history that pandemics are not over with a wave, but can sometimes flare up again. But what does this mean for the development of this Covid – 19 – Epidemic?

For Berlin, researchers have now calculated the effects of school openings in a model that is exclusively available to the Tagesspiegel. The result of the experts is unsettling.

Even if the distance rules that have now been adopted in schools in Berlin are successful, the close contacts of schoolchildren relevant to infection compared to the time before school closings at the 15. March by half, there would again be an exponential virus spread, critical for the health system, in the city . This is the result of the international research group Mocos (Modeling Coronavirus Spread), to which Wolfgang Bock, mathematician at the University of Kaiserslautern, belongs.

Coronavirus: Much fewer contacts than necessary before closing school

If it succeeds, the friendliness of the 15 – bis 18 – yearlings in the school to 18 percent, infect themselves accordingly within 300 days about 7800 Berliners and 156 die overall. Subtract from this you have to 5500 infected and 128 dead people who would also exist without school closings. But if only a contact reduction to 80 percent is achieved in this age range, i.e. 8 instead of 10 contacts, then almost thirty times as many Berliners, about 200. 000, infected and about 3000 People die. Even halving the contacts of high school students (48 percent still leads to round 2700 dead and 185. 000 infected.

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In their calculations, however, the researchers assume that the rest of the population will continue to drastically reduce their contacts – to around nine percent compared to before lockdown. Already with a doubling of the contacts in the total population (on 18 Percent), which would still be “relatively restrictive” according to Bock, the school openings have an impact: To 19. 000 Covid – 19 dead, that would come about in this scenario even without open schools, would be through the school openings further 3600 Covid – 19 – Dead after 300 days to add if 15- to 18 – Yearlings only half as many contacts as usual.

These numbers could even be exceeded. Because the researchers assume in their simulation that the strict contact reductions are maintained outside of schools – at nine percent compared to before 15. March. Taking into account the current easing measures in shops, workplaces or leisure facilities would rather lead to more infected people and deaths. They also start the calculation with about 1000 infected people in the 3.4 million city, which is about corresponds to the number of people currently ill.

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Health authorities are also generously factored in, who manage to mildly treat Covid at least every tenth – 19 to find the sick person within two days and to initiate the appropriate quarantine measures for him and his contacts. Furthermore, the researchers on 15- to 18- Year-olds are concentrated because they can be treated “almost like adults” when it comes to infection parameters, says Bock.

In younger people there are still discussions about how and whether these parameters differ. “We wanted to wait and see.” According to a study by the research team led by Charité virologist Christian Drosten, there are ages 0 to 6, 7 – 11 and 12 – 19 no significant differences from older ones in terms of the amount of viruses infected in the throat. Children are therefore “probably just as infectious as adults”. School openings also for the younger age groups could therefore exacerbate the scenario calculated by Bock's team.

Other modelers come to similar results

Kai Nagel from the Technical University also believes that the Mocos researchers' prognosis is going in the right direction. His team comes to very similar results using a method based on measured contact frequencies of people. “We can say a little more about what happens when you close leisure facilities or close shops, but the colleagues are a bit more precise in demography, that is, age differences in contact behavior.” But the result is comparable.

Nagel does not want to “lean as far out the window” as Bock's team, which clearly describes school openings as “too early”. In the end, that was a political decision, says Nagel. “But it is correct that there is little room for the relaxation of the contact restrictions, since even with just a little too much of the openings you can quickly get an exponential increase.”

A little more contacts in the general population, a lot more infections

The team also comments on the relaxation of contact restrictions in the general population of Berlin von Bock: “With a contact reduction of 54 even a detection of all can mild cases after two days do not prevent an epidemic from occurring that exceeds the load limit of the intensive care unit and causes the health system to collapse. “Inland 300 over a million people in Berlin would be infected.

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In order to be on the “safe” side, i.e. to keep the infection numbers below the load limit of the health system, the Berliners should only about 24 percent of your sociability (only 2.4 instead of 10 contacts) compared to the time before 15. March show – provided the health authorities discover and isolate at least every second case of infection within two days. But even if the townspeople only have six percent more contacts, i.e. 3 instead of 10 as before Corona, then the infection numbers jump up within 300 days several hundred thousand.

The leeway between just tolerable and too much sociability is “very small”. This cannot be changed by “massive testing”. But the more often and quickly infected people are discovered by the authorities and quarantine measures are taken, the more contacts the population could be allowed to do without risking a critical spread.

Don't leave schools alone, ”says Bock. It took a lot of testing capacity and schools had to have the time and resources to organize contact restrictions. But even if all of this works perfectly: More than half as many contacts as before corona times ( According to the scenario of the researchers, there should be no population in any case.

Linking of the corona infection chains via Schools and families

The main reason for this, according to the researchers, is that there is a Sars-CoV-2 infected within a household with a mild course of the disease, soon the rest of the family or roommates will be infected. It is therefore sufficient to have a small number of infection chains that link one household to another in order to trigger great effects on the epidemic and lead to a “supercritical” spread.

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Schools are believed to play an important role in linking the chains. If contact reduction is not maintained until the epidemic has come to a standstill, a second outbreak, a second wave is possible, the researchers conclude: “In our opinion, opening schools and reducing social distance measures comes too early.”

Skeptical that contact restrictions in schools work in the long run

Norman Heise, Chairman of the State Parents Committee, is skeptical whether a contact rate of only 18 percent compared to pre-corona times is possible if more and more students return to the classrooms.

Schools have been open again since Monday, in fact the first days at schools in Berlin were very different, reports Heise. The students were instructed on how to behave. Some adhered to the distance rules, the one-way system worked well in some cases, so that the aisles remained quite empty.

In other schools, however hugged and hugged the teenagers in greeting, goodbye, then directly in front of the school building. Typical groups were formed. The first regulatory measures were also announced and pronounced. After a warning, the reference follows, then pupils are no longer allowed to go to school. Some might put it right there and therefore violate the ban on contact.

“We have never heard of a school that had to close during the emergency care period because of infections.” , Heise told the Tagesspiegel. “That means that the distance requirement is the means of choice and works. It remains to be seen how this will happen in view of the increased number of students.

But it will probably be difficult. “The more students return to higher grades, the more they will use public transport, which creates additional points of contact,” warned Heise. Some schools have already introduced a mask requirement – as in public transport – which partly only applies during breaks and partly also during lessons. (collaboration: Ronja Ringelstein)

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