8. April 2021, 10:14
A study by the Helmholtz Zentrum München comes to the result that three to four times more children in Bavaria were infected with SARS-CoV-2 during the second corona wave than reported via PCR tests. In addition, around eight times more children had antibodies against the coronavirus at the end of the second wave than at the end of the first wave. The results are relevant for decisions about measures to contain the pandemic.
The frequency of SARS-CoV-2 infections in children of preschool and school age is an important benchmark for deciding whether to open kindergarten and school. With the screening study “Fr1da”, researchers led by Anette-Gabriele Ziegler are examining children in Bavaria for an early stage of type 1 diabetes. These tests take blood samples. In order to make this valuable study infrastructure usable for combating the corona pandemic, the research group decided last year to also include SARS-CoV-2 antibody tests with particularly high accuracy in their investigations. During the first wave in spring 2020, the test results in the children examined showed a SARS-CoV-2 antibody frequency of 0.87 percent. This means that six times more children in Bavaria were infected with the coronavirus than reported via PCR tests (link to press release).
More infections during the second wave
With the continuation of the Fr1da study in Bavaria, the scientists have now found that the detection of SARS-CoV-2 antibodies was significantly increased during the second wave in autumn and winter. Preschool children had an antibody frequency of 5.6 percent in the test period between October 2020 and February 2021. For school children who were tested from November 2020 to February 2021, the value was even 8.4 percent. Overall, the antibody frequency at the end of the second wave (January and February 2021) was about eight times higher than at the end of the first wave (April to July 2020). The results also showed that in the second wave three to four times more preschool and school children in Bavaria were infected with SARS-CoV-2 than reported via PCR tests.
Many children are asymptomatic
Markus Hippich, first author of the study and scientist at Helmholtz Zentrum München, says: “The fact that the frequency of infection in children is higher than reported by the PCR-based virus monitoring is probably due in part to asymptomatic cases in childhood.” 92.6 percent of children who tested positive in the second wave completed questionnaires on symptoms. The proportion of antibody-positive children without symptoms in preschool children was 68.0 percent. For school children it was 51.2 percent.
According to the research group, the sharp increase in SARS-CoV-2 infections during the second wave is the result of a combination of different events. These include a generally higher virus exposure in autumn and winter, school openings and new, more infectious virus variants. Study leader Anette-Gabriele Ziegler explains: “It is often assumed that children are less susceptible to SARS-CoV-2 infection than adults. However, the data on this is sparse. The results of our study clearly show that both preschool and school children are susceptible to SARS-CoV-2 infection. In order to get a better grip on the infection process in this population group, appropriate measures to contain the spread of the virus in kindergartens and schools could be helpful. “
Antibodies detectable for several months
Within the study, children who tested positive for SARS-CoV-2 antibodies could submit another sample to check the development of the antibody status. The scientists observed that the titer of the antibodies in the blood increased within an average of three months after the first sample. A total of 64 of 66 children in the follow-up remained positive for SARS-CoV-2 antibodies. The research group assumes that this is less the result of a renewed infection and more the natural course after a corona infection.
No association between type 1 diabetes and COVID-19 in children
The Fr1da study examines children in Bavaria up to the age of 10 for presymptomatic type 1 diabetes, which is defined by multiple islet autoantibodies. A connection between presymptomatic type 1 diabetes (positive test for islet autoantibodies) and a previous illness from COVID-19 (positive test for SARS-CoV-2 antibodies) could not be established during the first or second wave.
Limitations of the Study
Antibodies against SARS-CoV-2 are only detectable after one to four weeks. Therefore, these measured values cannot be used to make statements about the current infection rate.
About the study
This study was supported with funds from the Federal Ministry of Education and Research (BMBF) and the German Center for Diabetes Research (DZD). The Fr1da study is funded by the LifeScience Foundation, JDRF and The Helmsley Charitable Trust.
Helmholtz Centre Munich
As a research center, the Helmholtz Zentrum München pursues the mission of developing personalized medical solutions for the prevention and therapy of environmentally-related diseases for a healthier society in a rapidly changing world. It researches the development of common diseases in the context of environmental factors, lifestyle and individual genetic disposition. The center places a special focus on research into diabetes mellitus, allergies and chronic lung diseases. The headquarters of the center is in Neuherberg in the north of Munich. The Helmholtz Zentrum München employs around 2,500 people and is a member of the Helmholtz Association, the largest scientific organization in Germany with more than 40,000 employees in 19 research centers.
Prof. Anette-Gabriele Ziegler
Helmholtz Centre Munich
Email: [email protected]
Hippich et al., 2021: A Public Health Antibody Screening Indicates a Marked Increase of SARS-CoV-2 Exposure Rate in Children during the Second Wave. Med, DOI: 10.1016/j.medj.2021.03.019