Lombardy is the Italian region most affected by COVID-19. We tested the presence of plasma anti-SARS-CoV-2 IgG antibodies in 3985 employees across 7 healthcare facilities in areas of Lombardy with different exposure to the SARS-CoV-2 epidemic. Subjects filled a questionnaire to self-report on COVID-19 symptoms, co-morbidities, smoking, regular or smart-working, and the exposure to COVID-infected individuals. We show that the number of individuals exposed to the virus depended on the geographical location of the facility, ranging between 3 and 43%, consistent with the spatial variation of COVID-19 incidence in Lombardy, and correlated with family contacts. We observed a higher prevalence of females than males positive for IgG, however the level of antibodies was similar, suggesting a comparable magnitude of the response. IgG positivity among smokers was lower (7.4% vs 13.5%) although without difference in IgG plasma levels. We observed 11.9% of IgG positive asymptomatic individuals and another 23.1% with one or two symptoms. Interestingly, among the IgG positive population, 81.2% of subjects with anosmia/dysgeusia and fever were SARS-CoV-2 infected, indicating that these symptoms are strongly associated to COVID-19. The plasma level of IgG inversely correlated with anti-pneumococcal vaccination. In conclusion, the frequency of IgG positivity and SARS-CoV-2 infection is dependent on the geographical exposure to the virus and primarily to family rather than hospital exposure.

中文翻译：

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来自意大利伦巴第的7名医院代表的SARS-CoV-2不同暴露水平的卫生保健和管理人员人群中的IgG血清学

伦巴第是受COVID-19影响最大的意大利地区。我们在伦巴第地区的7个医疗机构的3985名员工中检测了抗SARS-CoV-2 IgG血浆抗体的存在情况，这些机构分别暴露于SARS-CoV-2流行病的不同暴露水平。受试者填写了一份问卷，以自我报告COVID-19症状，合并症，吸烟，正常或聪明工作以及接触COVID感染者的情况。我们显示，暴露于病毒的个体数量取决于设施的地理位置，介于3％和43％之间，与伦巴第的COVID-19发病率的空间变化一致，并与家庭成员相关。我们观察到，IgG阳性的女性患病率高于男性，但是抗体水平相似，表明反应的程度相当。吸烟者的IgG阳性率较低（7.4％比13.5％），尽管IgG血浆水平无差异。我们观察到11.9％的IgG阳性无症状个体和另外23.1％的有一种或两种症状的个体。有趣的是，在IgG阳性人群中，有失眠/消化不良和发烧的受试者中有81.2％感染了SARS-CoV-2，表明这些症状与COVID-19密切相关。IgG的血浆水平与抗肺炎球菌疫苗接种呈负相关。总之，IgG阳性和SARS-CoV-2感染的频率取决于病毒的地域暴露，主要取决于家庭而不是医院。在IgG阳性人群中，有失眠/消化不良和发烧的受试者中有81.2％感染了SARS-CoV-2，表明这些症状与COVID-19密切相关。IgG的血浆水平与抗肺炎球菌疫苗接种呈负相关。总之，IgG阳性和SARS-CoV-2感染的频率取决于病毒的地域暴露，主要取决于家庭而不是医院。在IgG阳性人群中，有失眠/消化不良和发烧的受试者中有81.2％感染了SARS-CoV-2，表明这些症状与COVID-19密切相关。IgG的血浆水平与抗肺炎球菌疫苗接种成反比。总之，IgG阳性和SARS-CoV-2感染的频率取决于病毒的地域暴露，主要取决于家庭而不是医院。