CD40LG and COVID-19: The results of the multivariable logistic regression analysis indicated that the probability of testing positive at IgG/IgM antibody was associated to level of exposure at SARS-CoV-2 at work (OR 3.09; 95% CI, 2.03-4.70; p < 0.0001), after adjusting for COVID-19-related symptom (OR 5.77; 95% CI, 3.80-8.76; p < 0.0001) and age (OR 1.03 per year; 95% CI, 1.01—1.05; p < 0.0001) (Table 4).