Moreover, the time course of NP positivity and seroconversion may vary and its related to the time of first contamination (Sethuraman et al., 2020). Our study has some limitations. 4.97% [95%CI 4.69C5.25]. No statistical difference was found among gender while seroprevalence was associated with subjects age, geographical location, and occupational sector. Significantly higher values of positivity were observed for the logistics sector (31.3%), weaving factory (12.6%), nursing homes (9.8%), and chemical industry (6.9%) workers. However, we Zfp622 observed some clusters of cases in single companies independently from the sector. Then, a detailed focus on 940 food workers shown a seroprevalence of 5.21% [95%CI 3.79C6.63] and subjects who self-reported COVID-19 symptoms and who worked during lockdown had a higher probability of being infected (< 0.001). Conclusions Data obtained might be useful for future public health decision; more than occupation sector, it seems that failure on prevention system in single companies increase the SARS-CoV-2 transmission. Keywords: seroprevalence, workers, SARS-CoV-2 Whats Important About This Paper? The effect of severe acute respiratory coronavirus 2 (SARS-CoV-2) viral circulation among active workers is usually poor known. Between March 28 and August 7 in North-West Italy, the proportion of SARS-CoV-2 positive workers was 4.97%, and significant differences were found among occupational sectors, with the highest seroprevalences in logistics (31.25%). However, single companies (independently of the sectors) may have had an important role in SARS-CoV-2 transmission, as clusters were detected. This indicates the need Bumetanide for infection prevention in workplaces. Introduction Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was identified in December 2019, as the cause of the illness designated Coronavirus Disease 2019 (COVID-19) (Zhu < 0.05 and data were analyzed using SAS 9.4 (SAS Institute, Cary, North Carolina) and R software. Results From 28 April to 7 August 2020, we collected the results for 23568 serological assessments from a convenience sample of 22708 workers from about 1000 companies; for 463 individuals more than one test was performed. About 60% (= 13613) of the participants were men with median age of 45 [IQR 36C52] years. The majority of subjects worked in Torino (41.0%), Biella (14.1%), Cuneo (12.2%), and Novara (8.0%); while the remaining were located in other Piedmont or North-Western Italian counties. Overall, 1129 workers had SARS-CoV-2 IgG positive measurements and the estimated seroprevalence was 4.97% [IC 95% 4.69C5.25]. Seroprevalences by general demographic characteristics are reported in Table 1. No statistical difference was found between genders (= 22708)= 1129)(%)< 0.001); details on seroprevalence across provinces are reported in Fig. 1. Despite few workers came from the provinces of Bergamo (= 32) and Brescia (= 20), these were the most affected areas, with prevalences of 25% and 15%, respectively. Significantly higher prevalences were observed for workers from Novara (6.70%, 95%CI 5.55C7.86), Alessandria (6.73%, 95%CI 5.18C8.29), and Vercelli (8.02%, 95%CI 6.51C9.54). Open in a separate window Physique 1. Map of seroprevalence of workers. Colors indicate lower and higher prevalence based on quartiles.Province abbreviation: AO = Aosta, Varese = VA, Asti = AT, Cuneo = CN, Biella = BI, Milano = MI, Torino = TO, Verbania = VB, Genova = GE, Novara = NO, Alessandria = AL, Vercelli = VC, Brescia = BS, Bergamo = BG. . A significant association was also found between seroprevalence and occupational sectors (< 0.0001). Significantly higher values of seroprevalence were observed for the logistics sector (31.25%, IC95% 8.54C53.96) and weaving factory (12.6%, IC95% 9.23C15.97) workers. However, in the first group the 95% CI were very wide due to low numbers of subjects analyzed (= 16), whereas in the second group possible clusters of infected cases were suggested, since in two weaving companies 41.5% and 9.9% of subjects (27/65, 9/91) were IgG positive. The health care workers, involved in private health services and private nursing homes, had IgG positive proportions of 5.20% [95%CI 3.90C6.51] and 9.78% [95%CI 7.66C11.89], respectively. In three nursing homes serological positivity was higher than 25% with 22/57 (38.6%), 10/32 (31.3%) and 7/28 (25.0%) positive subjects. Also in the chemical industry widespread of contamination was observed with a prevalence of positive IgG of 6.93% [95%CI 5.37C8.48], with peaks of 81.8% and 46.2% in two small companies (9/11, 6/13). Conversely, significant low prevalences were found in agriculture (2.79%, 95%CI Bumetanide 1.08C4.49), mechanical engineering (3.38%, 95%CI 2.59C4.16), and other manufacturing sector (3.64 95%CI 2.83C4.45). Finally, subjects involved in the food industry had a mean seroprevalence close to Bumetanide 5%, with important differences, since in some plants we observed more than 13% of positive workers (14/106 = 13.2% and 14/99 = 14.1%). Four thousand three hundred sixty-six NP swabs were performed for the search of SARS-CoV-2 computer virus after the result of the serological test:.