ABSTRACT
PURPOSE: Antibody assays against SARS-CoV-2 are used in sero-epidemiological studies to estimate the proportion of a population with past infection. IgG antibodies against the spike protein (S-IgG) allow no distinction between infection and vaccination. We evaluated the role of anti-nucleocapsid-IgG (N-IgG) to identify individuals with infection more than one year past infection. METHODS: S- and N-IgG were determined using the Euroimmun enzyme-linked immunosorbent assay (ELISA) in two groups: a randomly selected sample from the population of Stuttgart, Germany, and individuals with PCR-proven SARS-CoV-2 infection. Participants were five years or older. Demographics and comorbidities were registered from participants above 17 years. RESULTS: Between June 15, 2021 and July 14, 2021, 454 individuals from the random sample participated, as well as 217 individuals with past SARS-CoV-2 infection. Mean time from positive PCR test result to antibody testing was 458.7 days (standard deviation 14.6 days) in the past infection group. In unvaccinated individuals, the seroconversion rate for S-IgG was 25.5% in the random sample and 75% in the past infection group (P = < 0.001). In vaccinated individuals, the mean signal ratios for S-IgG were higher in individuals with prior infection (6.9 vs 11.2; P = < 0.001). N-IgG were only detectable in 17.1% of participants with past infection. Predictors for detectable N-IgG were older age, male sex, fever, wheezing and in-hospital treatment for COVID-19 and cardiovascular comorbidities. CONCLUSION: N-IgG is not a reliable marker for SARS-CoV-2 infection after more than one year. In future, other diagnostic tests are needed to identify individuals with past natural infection.
ABSTRACT
The stress response to the COVID-19 pandemic might differ between early and later stages. Longitudinal data on the development of population mental health during COVID-19 pandemic is scarce. We have investigated mental health trajectories and predictors for change in a probability sample of the general population in Germany at the beginning and after 6 months of the pandemic. We conducted a longitudinal survey in a population-based probability sample of German adults. The current study analyzed data from a first assessment in May 2020 (T1;N = 1,412) and a second in November 2020 (T2;N = 743). Mental health was assessed in terms of anxiety and depression using the Patient Health Questionnaire-4 (PHQ-4). Mental health outcomes at T1 were compared with PHQ-4 norm data. Trajectories over time were investigated based on outcome classifications of PHQ-4 scores. Predictors of mental health outcomes and change were identified using multiple regression analysis. In spring 2020, participants showed significantly higher PHQ-4 scores as compared to the norm data, however, overall anxiety and depression remained low also 6 months later. 6.6% of respondents showed a mental health deterioration in autumn 2020, entering subclinical and clinical ranges, outweighing the proportion of people with improved outcomes. Sociodemographic variables associated with mental distress at T1 were mainly not predictive for change at T2. Even under prolonged pandemic-related stress, mental health remained mainly stable in the general population. Further development of the considerable subgroup experiencing deterioration of depression and anxiety should be monitored, in order to tailor prevention and intervention efforts.