The medical faculty of the TU Dresden and Dresden University Hospital Carl Gustav Carus started a study on the spread of the SARS-CoV-2 virus in Saxon schools in May 2020. On Monday, the study makers presented the results of the first test phase with over 2,000 participants.
It is the largest study in Germany to date, as part of the reopening of the schools after the lockdown, to record how many students and teachers carry antibodies against the SARS-CoV-2 virus and how its spread changes over time.
The numbers provide information about the current immunity status of teachers and students. They therefore provide important clues as to how school operations can continue after the summer holidays.
Abstract:
Low degree of immunisation: Of the 2045 blood samples examined, 12 were undoubtedly found to be antibodies against the SARS-CoV-2 virus. This means that the degree of immunization in the group of study participants is well below one percent (0.6%) and is lower than forecast.
Up to now, the dynamics of virus spreading have been overestimated. So far, this has apparently been overestimated. Because in 24 families of the study participants there was at least one confirmed corona case, but only one of the test persons was able to detect antibodies.
Schools did not become a hotspot after reopening: Corona cases were confirmed in three of the schools examined. Nevertheless, above average antibodies were not detectable among the teachers and students of the institutions concerned, which suggests that the schools have not developed into hotspots.
In May and June, physicians from the Dresden University Hospital Carl Gustav Carus examined a total of 2045 blood samples from schoolchildren and teachers from 13 secondary schools in Dresden and the districts of Bautzen and Görlitz. Of the 2,045 samples, 1,541 came from schoolchildren, mostly in grades eight to eleven. In addition, a total of 504 teachers participated, their ages ranged from 30 to 66 years. The proportion of male and female study participants was roughly the same among schoolchildren, with 70% of teachers dominating teachers. Corona cases were diagnosed in some of the 13 schools.
According to the medical history, five study participants indicated that they had previously tested positive for the SARS-CoV-2 virus. There were also 24 households in which a family member had tested positive in advance. Doctors at the University Hospital Dresden each took five millilitres of blood from the arm vein of the students and teachers. “All samples were subjected to a uniform, approved antibody test. It is suitable for automated systems and identifies antibodies to the spike protein of the SARS-CoV2 virus in the serum,” explains Professor Alexander Dalpke, director of the Institute of Virology at the medical faculty of the TU Dresden.
The results:
Antibodies could be detected without any doubt in 12 of the 2,045 samples at the Institute of Virology. For this purpose, samples with a positive test result were subjected to two further antibody tests. If at least one of the additional tests was positive, the study participant is considered an antibody carrier. In five of the twelve cases there was a known proven corona virus infection, in seven cases the infection was not known in advance. This means that the number of unreported infections among the study participants is just over two.
Professor Reinhard Berner, clinic director of the clinic and polyclinic for paediatrics and adolescent medicine of the University Hospital Carl Gustav Carus and director of studies said: “We are going into the summer vacation 2020 with an immunity status that is no different from that in March 2020. Of the more than 2,000 blood samples examined, only 12 were able to detect antibodies, which corresponds to a share of well below one percent. This means that a silent, symptom-free infection in the students and teachers we examined has so far occurred less frequently than we had suspected.
“It is also striking that in the 24 households in which at least one corona case was known, apparently only one infection occurred, according to which the corresponding antibodies can now be detected.
“These results of the investigation provide evidence that virus transmission in families is not as dynamic as previously thought. More than 20 of the examined subjects had at least one proven corona case in the family; however, antibodies were found in only one of these study participants, which would mean that the majority of schoolchildren did not go through an infection themselves despite an infection in the household. This finding must also be taken into account when it comes to deciding on measures to limit contact.
“For the study, pupils from the eighth to eleventh grades were deliberately selected because these pupils move to a greater extent regardless of their parents' house and perhaps also from the requirements of the general decree, and they also accept a correspondingly large number of social contacts. Schools were also deliberately selected for the study, and it was known that SARS-CoV2 infections had been detected there prior to the lockdown.
“Fortunately, we were able to determine that hotspots did not develop in the selected age group and in the schools examined, neither before the lockdown nor after the reopening. Four out of five students – 80% – stated that they had regular social contacts beyond their class group and the family. That also apparently did not lead to a further spread of the virus."
“Blood samples were taken again last week – 105 of the study participants, which corresponds to around 200 pupils and teachers, were tested again, in the schools where sampling had started on 25 May.”
The second large series of tests at all 13 schools is planned for the beginning of the new school year, and a third will take place at the end of 2020 or early 2021 depending on the level of infection, says Berner, together with Dr Jakob Armann and Dalpke.
Together they warned against having a positive antibody test as no license, because the detection of antibodies does not necessarily mean protection. “In addition, there are so-called false positive results for each test, which indicate putative antibodies that are actually not available. We have therefore subjected two further tests to positive results,” Dalpke. Only those who were positive in two of the three procedures were classified as antibody carriers.
It is therefore crucial to look at the development of antibodies over the course, the virologist says.
The study funded by the Free State of Saxony is therefore also scheduled to run for two years.
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