Monitoring the SARS-CoV-2 Pandemic: Prevalence of Antibodies in a Large, Repetitive Cross-Sectional Study of Blood Donors in Germany-Results from the SeBluCo Study 2020-2022.

SARS-CoV-2 serosurveillance is important to adapt infection control measures and estimate the degree of underreporting. Blood donor samples can be used as a proxy for the healthy adult population. In a repeated cross-sectional study from April 2020 to April 2021, September 2021, and April/May 2022, 13 blood establishments collected 134,510 anonymised specimens from blood donors in 28 study regions across Germany. These were tested for antibodies against the SARS-CoV-2 spike protein and nucleocapsid, including neutralising capacity. Seroprevalence was adjusted for test performance and sampling and weighted for demographic differences between the sample and the general population. Seroprevalence estimates were compared to notified COVID-19 cases. The overall adjusted SARS-CoV-2 seroprevalence remained below 2% until December 2020 and increased to 18.1% in April 2021, 89.4% in September 2021, and to 100% in April/May 2022. Neutralising capacity was found in 74% of all positive specimens until April 2021 and in 98% in April/May 2022. Our serosurveillance allowed for repeated estimations of underreporting from the early stage of the pandemic onwards. Underreporting ranged between factors 5.1 and 1.1 in the first two waves of the pandemic and remained well below 2 afterwards, indicating an adequate test strategy and notification system in Germany.

COVID-19 vaccination status among people with selected citizenships: results of the study GEDA Fokus.

Background: the COVID-19 vaccination offers protection against severe disease progression. Data show that people with a history of migration are less likely to be vaccinated against COVID-19 than people without a history of migration, but are at increased risk of infection. Methods: Data were used from the GEDA Fokus interview survey (November 2021 - May 2022), which included people living in Germany with Croatian, Italian, Polish, Syrian or Turkish citizenship (n=5,495). In addition to bivariate analyses, Poisson regressions were used to examine the association between uptake of at least one COVID-19 vaccination and sociodemographic, health- and migration-related factors. Results: 90.0% of participants reported having received at least one COVID-19 vaccination. Having visited a general practitioner or specialist in the past 12 months, living in Germany for 31 years or more, and having a greater sense of belonging to society in Germany were associated with vaccination uptake in bivariate analyses. Regression analysis showed that older people and those with higher education were more likely to be vaccinated. Conclusions: Sociodemographic factors are associated with uptake of the COVID-19 vaccine among individuals with selected citizenships. Low-threshold information and vaccination offers are important to ensure equal access to vaccination.

Estimating the share of SARS-CoV-2-immunologically naïve individuals in Germany up to June 2022.

After the winter of 2021/2022, the coronavirus disease 2019 (COVID-19) pandemic had reached a phase where a considerable number of people in Germany have been either infected with a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant, vaccinated or both, the full extent of which was difficult to estimate, however, because infection counts suffer from under-reporting, and the overlap between the vaccinated and recovered subpopulations is unknown. Yet, reliable estimates regarding population-wide susceptibility were of considerable interest: Since both previous infection and vaccination reduce the risk of severe disease, a low share of immunologically naïve individuals lowers the probability of further severe outbreaks, given that emerging variants do not escape the acquired susceptibility reduction. Here, we estimate the share of immunologically naïve individuals by age group for each of the sixteen German federal states by integrating an infectious-disease model based on weekly incidences of SARS-CoV-2 infections in the national surveillance system and vaccine uptake, as well as assumptions regarding under-ascertainment. We estimate a median share of 5.6% of individuals in the German population have neither been in contact with vaccine nor any variant up to 31 May 2022 (quartile range [2.5%-8.5%]). For the adult population at higher risk of severe disease, this figure is reduced to 3.8% [1.6%-5.9%] for ages 18-59 and 2.1% [1.0%-3.4%] for ages 60 and above. However, estimates vary between German states mostly due to heterogeneous vaccine uptake. Excluding Omicron infections from the analysis, 16.3% [14.1%-17.9%] of the population in Germany, across all ages, are estimated to be immunologically naïve, highlighting the large impact the first two Omicron waves had until the beginning of summer in 2022. The method developed here might be useful for similar estimations in other countries or future outbreaks of other infectious diseases.

Nationally representative results on SARS-CoV-2 seroprevalence and testing in Germany at the end of 2020.

Pre-vaccine SARS-CoV-2 seroprevalence data from Germany are scarce outside hotspots, and socioeconomic disparities remained largely unexplored. The nationwide representative RKI-SOEP study (15,122 participants, 18-99 years, 54% women) investigated seroprevalence and testing in a supplementary wave of the Socio-Economic-Panel conducted predominantly in October-November 2020. Self-collected oral-nasal swabs were PCR-positive in 0.4% and Euroimmun anti-SARS-CoV-2-S1-IgG ELISA from dry-capillary-blood antibody-positive in 1.3% (95% CI 0.9-1.7%, population-weighted, corrected for sensitivity = 0.811, specificity = 0.997). Seroprevalence was 1.7% (95% CI 1.2-2.3%) when additionally correcting for antibody decay. Overall infection prevalence including self-reports was 2.1%. We estimate 45% (95% CI 21-60%) undetected cases and lower detection in socioeconomically deprived districts. Prior SARS-CoV-2 testing was reported by 18% from the lower educational group vs. 25% and 26% from the medium and high educational group (p < 0.001, global test over three categories). Symptom-triggered test frequency was similar across educational groups. Routine testing was more common in low-educated adults, whereas travel-related testing and testing after contact with infected persons was more common in highly educated groups. This countrywide very low pre-vaccine seroprevalence in Germany at the end of 2020 can serve to evaluate the containment strategy. Our findings on social disparities indicate improvement potential in pandemic planning for people in socially disadvantaged circumstances.

Seroepidemiological study on the spread of SARS-CoV-2 in Germany: Study protocol of the CORONA-MONITORING bundesweit' study (RKI-SOEP study).

The SARS-CoV-2 coronavirus has spread rapidly across Germany. Infections are likely to be under-recorded in the notification data from local health authorities on laboratory-confirmed cases since SARS-CoV-2 infections can proceed with few symptoms and then often remain undetected. Seroepidemiological studies allow the estimation of the proportion in the population that has been infected with SARS-CoV-2 (seroprevalence) as well as the extent of undetected infections. The 'CORONA-MONITORING bundesweit' study (RKI-SOEP study) collects biospecimens and interview data in a nationwide population sample drawn from the German Socio-Economic Panel (SOEP). Participants are sent materials to self-collect a dry blood sample of capillary blood from their finger and a swab sample from their mouth and nose, as well as a questionnaire. The samples returned are tested for SARS-CoV-2 IgG antibodies and SARS-CoV-2 RNA to identify past or present infections. The methods applied enable the identification of SARS-CoV-2 infections, including those that previously went undetected. In addition, by linking the data collected with available SOEP data, the study has the potential to investigate social and health-related differences in infection status. Thus, the study contributes to an improved understanding of the extent of the epidemic in Germany, as well as identification of target groups for infection protection.

German and international studies on SARS-CoV-2 seroprevalence.

Since the beginning of the year 2020, the SARS-CoV-2 coronavirus has spread globally at a tremendous pace. Studies on the prevalence of SARS-CoV-2 antibodies in the population help estimate the number of people that have already been infected. They also allow an estimate of the number of undetected infections i.e. infections that do not appear in data on officially reported cases. The interpretation of study results needs to consider bias from selective sampling and the diagnostic test properties. To promote networking and co-operation between scientists, the Robert Koch Institute has compiled an overview of the seroepidemiological studies conducted in Germany on its website, which is regularly updated. The RKI conducts searches, for example of press releases, study registry entries or preprint server publications, and contacts the lead investigators of these studies. Of the 40 studies contacted so far, 24 have already provided information (as of 25.06.2020). We can differentiate between studies of the general population, of selected population groups such as healthcare workers, or of ongoing cohorts. This article provides an overview of such studies from Germany, but also of selected international studies. A special focus is set on studies of children and adolescents, which are now of particular interest due to the planned reopening of childcare facilities and schools.

[Seroprevalence of SARS-CoV-2 among children and adolescents in Germany-an overview]. / SARS-CoV-2-Seroprävalenz bei Kindern und Jugendlichen in Deutschland ­ ein Überblick.

BACKGROUND: SARS-CoV­2 serologic studies complement and expand findings from confirmed COVID-19 cases through identification of undetected cases. OBJECTIVES: This article summarizes previous results on SARS-CoV­2 prevalence from seroepidemiological studies in Germany focusing on children and adolescents and complements the already existing overview on seroprevalence in adults from general population samples and especially blood donors in Germany. METHODS: The results are based on an ongoing systematic search in study registries, in literature databases, of preprint publications, and of media reports of seroepidemiological studies in Germany and their results. RESULTS: As of 17 September 2021, we are aware of 16 German seroepidemiological studies focusing on children and adolescents. Results are available for nine of these studies. For almost all settings studied, SARS-CoV­2 seroprevalence was well below 1% for preschool and elementary school children in the first COVID-19 wave and below 2% for adolescents. As the pandemic progressed, higher seroprevalences of up to 8% were found in elementary school children. DISCUSSION: Results of SARS-CoV­2 antibody studies in children and adolescents in Germany are scarce so far and are based on non-representative samples at local or regional level. In future studies, it is necessary on the one hand to estimate which proportion of children and adolescents has already either had an infection or has been vaccinated. On the other hand, it is important to investigate physical and mental health impairments that occur after an infection.

[Seroprevalence of COVID-19 and Psychosocial Effects in the General Population: Results of the STAAB-COVID-One Program]. / Seroprävalenz von COVID-19 und psychosoziale Auswirkungen in der Allgemeinbevölkerung: Ergebnisse des STAAB-COVID-One Programms.

BACKGROUND: Research of SARS-CoV-2 has so far largely focused on symptomatic cases. The STAAB-COVID study therefore examined the seroprevalence of COVID-19 in the general population and the psychosocial effects of the pandemic. METHODS: From June-October 2020, a sub-study was conducted within the "Characteristics and Course of Heart Failure Stages A-B and Determinants of Progression (STAAB)" cohort study. 4,860 study participants identified from a representative age-stratified sample of Würzburg residents were asked to provide a blood sample and to fill in a questionnaire. All participants also received an offer to take part in a point prevalence assessment (nasal swab taken from the participant at the beginning of November 2020). RESULTS: A total of 3,034 subjects took part in the STAAB-COVID program (response rate 62%). Antibodies against SARS-CoV-2 were detected in 33 participants (1.1%; 95% confidence interval 0.7-1.5%). Higher values on the GAD-7 anxiety scale were associated with lower rates of SARS-CoV-2 antibodies (Odds Ratio=0.78 for each+1 point in GAD-7; 95% confidence interval 0.65-0.95). Within this rather anxious group of subjects, however, the rate of cancellation of medical appointments was also increased (Odds Ratio=1.13 for each+1 point in GAD-7; 95% confidence interval 1.10-1.16). An acute infection was detected in six of a total of 2,451 participants in the point prevalence assessment (0.24%; 95% confidence interval 0.09-0.53%). CONCLUSION: Between the first and second COVID-19 waves in Germany, we found a low level of SARS-CoV-2 contamination in the city of Würzburg. A more anxious personality was associated with a lower seroprevalence. Conducting the study was largely facilitated by the existing cohort study.

Socioeconomic position and SARS-CoV-2 infections: seroepidemiological findings from a German nationwide dynamic cohort.

BACKGROUND: Evidence on the relationship between socioeconomic position (SEP) and infections with SARS-CoV-2 is still limited as most of the available studies are ecological in nature. This is the first German nationwide study to examine differences in the risk of SARS-CoV-2 infections according to SEP at the individual level. METHODS: The 'CORONA-MONITORING bundesweit' (RKI-SOEP) study is a seroepidemiological survey among a dynamic cohort of the German adult population (n=15 122; October 2020-February 2021). Dried blood samples were tested for SARS-CoV-2 antibodies and oral-nasal swabs for viral RNA. SEP was measured by education and income. Robust logistic regression was used to examine adjusted associations of SARS-CoV-2 infections with SEP. RESULTS: 288 participants were seropositive, PCR positive or self-reported a previous laboratory-confirmed SARS-CoV-2 infection. The adjusted odds of SARS-CoV-2 infection were 1.87-fold (95% CI 1.06 to 3.29) higher among low-educated than highly educated adults. Evidence was weaker for income differences in infections (OR=1.65; 95% CI 0.89 to 3.05). Highly educated adults had lower odds of undetected infection. CONCLUSION: The results indicate an increased risk of SARS-CoV-2 infection in low-educated groups. To promote health equity in the pandemic and beyond, social determinants should be addressed more in infection protection and pandemic planning.

Serology- and PCR-based cumulative incidence of SARS-CoV-2 infection in adults in a successfully contained early hotspot (CoMoLo study), Germany, May to June 2020.

Three months after a coronavirus disease (COVID-19) outbreak in Kupferzell, Germany, a population-based study (n = 2,203) found no RT-PCR-positives. IgG-ELISA seropositivity with positive virus neutralisation tests was 7.7% (95% confidence interval (CI): 6.5-9.1) and 4.3% with negative neutralisation tests. We estimate 12.0% (95% CI: 10.4-14.0%) infected adults (24.5% asymptomatic), six times more than notified. Full hotspot containment confirms the effectiveness of prompt protection measures. However, 88% naïve adults are still at high COVID-19 risk.

Impact of sex and gender on COVID-19 outcomes in Europe.

BACKGROUND: Emerging evidence from China suggests that coronavirus disease 2019 (COVID-19) is deadlier for infected men than women with a 2.8% fatality rate being reported in Chinese men versus 1.7% in women. Further, sex-disaggregated data for COVID-19 in several European countries show a similar number of cases between the sexes, but more severe outcomes in aged men. Case fatality is highest in men with pre-existing cardiovascular conditions. The mechanisms accounting for the reduced case fatality rate in women are currently unclear but may offer potential to develop novel risk stratification tools and therapeutic options for women and men. CONTENT: The present review summarizes latest clinical and epidemiological evidence for gender and sex differences in COVID-19 from Europe and China. We discuss potential sex-specific mechanisms modulating the course of disease, such as hormone-regulated expression of genes encoding for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) entry receptors angiotensin converting enzyme (ACE) 2 receptor and TMPRSS2 as well as sex hormone-driven innate and adaptive immune responses and immunoaging. Finally, we elucidate the impact of gender-specific lifestyle, health behavior, psychological stress, and socioeconomic conditions on COVID-19 and discuss sex specific aspects of antiviral therapies. CONCLUSION: The sex and gender disparities observed in COVID-19 vulnerability emphasize the need to better understand the impact of sex and gender on incidence and case fatality of the disease and to tailor treatment according to sex and gender. The ongoing and planned prophylactic and therapeutic treatment studies must include prospective sex- and gender-sensitive analyses.