Seroprevalence of SARS-CoV-2 in German secondary schools from October 2020 to July 2021: a longitudinal study.

PURPOSE: To quantify the number of SARS-CoV-2 infections in students and teachers in 14 Secondary schools in eastern Saxony, Germany. Seroprevalence of SARS-CoV-2 antibodies in study population. Number of undetected cases. METHODS: Serial seroprevalence study. RESULTS: The role of educational settings in the SARS-CoV-2 Pandemic is still controversial. Seroprevalence increases from 0.8 to 5.9% from October to December when schools remained open and to 12.2% in March/April during a strict lockdown with closed schools. The ratio of undetected to detected cases decreased from 0.76 to 0.44 during the study period. CONCLUSION: During the second and third wave of the pandemic in Germany, students and teachers are not overrepresented in SARS-CoV-2 infections. The percentage of undetected cases is moderate and decreases over time. The risk of contracting SARS-CoV-2 within the household is higher than contracting it in educational settings making school closures rather ineffective in terms of pandemic control measures or individual risk reduction in children and adolescents. TRIAL REGISTRATION: DRKS00022455 (July 23rd, 2020).

Prevalence and Transmission of Severe Acute Respiratory Syndrome Coronavirus Type 2 in Childcare Facilities: A Longitudinal Study.

OBJECTIVE: To evaluate the role of childcare facilities in the transmission of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) in a longitudinal study to gain further knowledge of SARS-CoV-2 prevalence, transmission, and spread among preschool children, their parents, and their caregivers. STUDY DESIGN: Children aged 1-6 years, their parents, and their caregivers in 14 childcare facilities in Dresden, Saxony/Germany were invited to participate in the KiTaCoviDD19-study between July 2020 and January 2021. Seroprevalence of SARS-CoV-2 antibodies was assessed up to 4 times during the study period in all participating adults, and demographic characteristics, as well as epidemiologic information on personal SARS-CoV-2 history were obtained. Samples for stool virus shedding of SARS-CoV-2 were analyzed by polymerase chain reaction every 2-4 weeks in all participating children. RESULTS: In total, 318 children, 299 parents and 233 childcare workers were enrolled. By January 2021, 11% of the participating adults were found to be seropositive, whereas the percentage of children shedding SARS-CoV-2 was 6.8%. Overall, we detected 17 children with SARS-CoV-2 virus shedding in 8 different childcare facilities. In 4 facilities, there were a maximum of 3 connected cases in children. Approximately 50% of SARS-CoV-2 infections in the children could not be connected to a secondary case in our study population. CONCLUSIONS: This study does not provide evidence of relevant asymptomatic ("silent") spread of SARS-CoV-2 in childcare facilities in both low- and high-prevalence settings. Our findings add to the evidence that childcare and educational settings do not have a crucial role in driving the SARS-CoV-2 pandemic.

SARS-CoV-2 seroprevalence in students and teachers: a longitudinal study from May to October 2020 in German secondary schools.

OBJECTIVE: To quantify the number of SARS-CoV-2 infections in secondary schools after their reopening in May 2020. DESIGN: Repeated SARS-CoV-2 seroprevalence study after the reopening of schools and 4 months later. SETTING: Secondary school in Dresden, Germany. PARTICIPANTS: 1538 students grades 8-12 and 507 teachers from 13 schools. INTERVENTIONS: Serial blood sampling and SARS-CoV-2 IgG antibody assessment. PRIMARY AND SECONDARY OUTCOME MEASURE: Seroprevalence of SARS-CoV-2 antibodies in study population. Number of undetected cases. RESULTS: 1538 students and 507 teachers were initially enrolled, and 1334 students and 445 teachers completed both study visits. The seroprevalence for SARS-CoV-2 antibodies was 0.6% in May/June and the same in September/October. Even in schools with reported COVID-19 cases before the lockdown of 13 March, no clusters could be identified. Of 12 persons with positive serology five had a known history of confirmed COVID-19; 23 out of 24 participants with a household history of COVID-91 were seronegative. CONCLUSIONS: Schools do not play a crucial role in driving the SARS-CoV-2 pandemic in a low-prevalence setting. Transmission in families occurs very infrequently, and the number of unreported cases is low in this age group. These observations do not support school closures as a strategy fighting the pandemic in a low-prevalence setting. TRIAL REGISTRATION NUMBER: DRKS00022455.

Kinetics and seroprevalence of SARS-CoV-2 antibodies: a comparison of 3 different assays.

Comparing seroprevalence and antibody kinetics in three different commercially available assays for SARS-CoV-2. Serostatus of COVID-19 patients was analyzed 5 months and 10 months after their infection, using three different assays: Diasorin LIAISON, Euroimmun, Abbott Diagnostics ARCHITECT. Seropositivity at baseline differed significantly depending on the assay (Diasorin 81%, Euroimmun 83%, Abbott 59%). At follow-up antibody levels detected in the Diasorin assay were stable, while there was a significant loss in seropositivity in the Euroimmun and Abbott assays. There are significant differences in SARS-CoV-2 antibody kinetics based on the specific assay used.

Different Neural Processing of Umami and Salty Taste Determined by Umami Identification Ability Independent of Repeated Umami Exposure.

There is a large inter-individual variation for umami taste perception. However the neural mechanism for this variability is not well understood. This study investigated brain responses to umami and salty taste among individuals with different umami identification abilities and the effect of repeated oral umami exposure on umami identification and neural processing of taste perceptions. Fifteen participants with high umami identification ability ("High Tasters, HT) and fifteen with low umami identification ability ("Low Tasters", LT) underwent three weeks of controlled exposure to umami taste (umami training). Prior to and after the training, participants underwent fMRI scans during which the umami taste solution and a control taste (salty) solution were delivered to their mouth using a gustometer. Taste intensity and pleasantness were rated after each scan. Umami taste identification was assessed before and after the umami training using "Taste Strips" test. Neuroimaging results showed different central processing of umami and salty taste based on umami identification ability, in which the umami LT had stronger activation in the thalamus and hippocampus while the umami HT showed stronger activation in the primary gustatory cortex. In addition, umami identification was significantly improved after umami training for LT. However, it was not reflected in changes in neural activation. The current study shows that attention and association/memory related brain structures play a significant role in the perception of umami taste; and with reference to the results of repeated umami exposure, the presence of very subtle changes regarding the neural processing.