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Background: The duration of immune response to COVID-19 vaccination is of major interest. Our aim was to analyze the determinants of anti-SARS-CoV-2 IgG titer at 6 months after 2-dose vaccination in an international cohort of vaccinated healthcare workers (HCWs)., Methods: We analyzed data on levels of anti-SARS-CoV-2 Spike antibodies and sociodemographic and clinical characteristics of 6,327 vaccinated HCWs from 8 centers from Germany, Italy, Romania and Slovakia. Time between 1 st dose and serology ranged 150-210 days. Serological levels were log-transformed to account for the skewness of the distribution and normalized by dividing them by center-specific standard errors, obtaining standardized values. We fitted center-specific multivariate regression models to estimate the cohort-specific relative risks (RR) of an increase of 1 standard deviation of log antibody level and corresponding 95% confidence interval (CI), and finally combined them in random-effects meta-analyses., Results: A 6-month serological response was detected in 99.6% of HCWs. Female sex (RR 1.10, 95%CI 1.00-1.21), past infection (RR 2.26, 95%CI 1.73-2.95) and two vaccine doses (RR 1.50, 95%CI 1.22-1.84) predicted higher IgG titer, contrary to interval since last dose (RR for 10-day increase 0.94, 95%CI 0.91-0.97) and age (RR for 10-year increase 0.87, 95%CI 0.83-0.92). M-RNA-based vaccines (p<0.001) and heterologous vaccination (RR 2.46, 95%CI 1.87-3.24, one cohort) were associated with increased antibody levels., Conclusions: Female gender, young age, past infection, two vaccine doses, and m-RNA and heterologous vaccination predicted higher antibody level at 6 months. These results corroborate previous findings and offer valuable data for comparison with trends observed with longer follow-ups., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Collatuzzo, Visci, Violante, Porru, Spiteri, Monaco, Larese Fillon, Negro, Janke, Castelletti, De Palma, Sansone, Mates, Teodorescu, Fabiánová, Bérešová, Vimercati, Tafuri, Abedini, Ditano, Asafo, Boffetta and Orchestra WP5 Working Group.)

Background: Dermal risk assessment of exposure to chemicals is difficult due to the lack of standardisation of the methods used in exposure quantification; further limits concern the extent of skin contamination and especially dermal absorption of different substances. To solve these problems many authors proposed conceptual models founded on theoretical assumptions and experimental data, but their use in occupational settings revealed many difficulties. A possible alternative is the use of a check-list that permits evaluation of occupational dermal contamination hazards., Aims: To propose a simplified method for dermal risk assessment., Methods: Dermal contamination risk evaluation, chemical hazard quantification and duration of exposure are the basic features of the method. The first step assesses working conditions, use of protective devices, skin contamination directly observed, personal hygiene of workers: all information, collected by a trained observer, is scored according to literature data and/or to authors'personal experience. Chemical hazard quantfication is obtained from safety data sheet evaluation (R phrases classification and chemical-physical characteristics of the chemical in use). The method allows a preliminary dermal exposure assessment to be made, subdivided on hazard bands., Results: The method permits a rapid dermal exposure assessment to be made and suggests intervention measures to decrease dermal risk., Conclusions: A check-list is proposed that can be a useful and easy method to assess dermal exposure to chemicals, particularly in small- and medium-sized enterprises.

The dermal risk assessment requires simplified methodologies to understand the role played by the skin. The conceptual models proposed to this aim are founded on theoretical assumptions and experimental data, but their use in occupational settings shows many difficulties. For this end we have drawn up a check-list that includes six sessions and allows to obtain a preliminary dermal exposure evaluation subdivided on hazard bands.