Population-based study of the durability of humoral immunity after SARS-CoV-2 infection

SARS-CoV-2 antibody quantity and quality are key markers of humoral immunity. However, there is substantial uncertainty about their durability. We investigated levels and temporal change of SARS-CoV-2 antibody quantity and quality. We analyzed sera (8 binding, 4 avidity assays for spike-(S-)protein and nucleocapsid-(N-)protein; neutralization) from 211 seropositive unvaccinated participants, from the population-based longitudinal TiKoCo study, at three time points within one year after infection with the ancestral SARS-CoV-2 virus. We found a significant decline of neutralization titers and binding antibody levels in most assays (linear mixed regression model, p<0.01). S-specific serum avidity increased markedly over time, in contrast to N-specific. Binding antibody levels were higher in older versus younger participants – a difference that disappeared for the asymptomatic-infected. We found stronger antibody decline in men versus women and lower binding and avidity levels in current versus never-smokers. Our comprehensive longitudinal analyses across 13 antibody assays suggest decreased neutralization-based protection and prolonged affinity maturation within one year after infection

Respiratory symptoms and diseases among workers in the soft tissue producing industry

Aims: To correlate the prevalence of respiratory tract symptoms and diseases with dust and fibre exposure in the soft tissue industry in Germany. Methods: Ambient monitoring was performed for inhalable, respirable dust and fibres in seven soft tissue producing factories. In 441 workers (72 controls, 90 moderate, 279 high exposure) a standardised questionnaire on respiratory symptoms, diseases, occupational history, and smoking habits was used. Crude differences in the prevalence of respiratory symptoms and diseases were assessed. Logistic regression analysis was used to determine the relation between the respiratory symptoms/diseases and the cumulative dust and fibre exposure, respectively, while adjusting for age, gender, smoking habits, and factory. The effects of exposure intensity and duration were differentiated by categorising dust/fibre concentrations and years of exposure separately and setting up logistic regression models. Results: The mean concentrations for inhalable, respirable, and fibrous dusts were 10.3 mg/m(3), 0.22 mg/m(3), and 415 000 fibres/m(3). Adjusted odds ratios (OR) with relation to cumulative dust exposure intensity were significantly raised for blocked nose (18.2), mucosal irritation (6.5), dry nose (8.9), cough (3.5), phlegm (7.5), exercise induced dyspnoea (2.6), hoarseness (11.3), and sneezing attacks (7.9) (ORs for highest exposure categories). Cumulative dust or fibre exposure had no significant effects on the prevalence of respiratory diseases. For all symptoms with significantly raised ORs, combined effects of intensity and duration of exposure were found. Conclusions: Because of the high prevalence of respiratory symptoms a reduction of dust exposures is recommended. Chronic exposure effects could not be found in this study, however, a healthy worker effect has to be considered