Background Health workers are at high risk for SARS-CoV-2 infection and, if asymptomatic, for transmitting the virus on to fragile cancer patients. Materials and method We monitored health care workers (HCW) of our Cancer Institute with the rapid serological test Viva-DiagTM analyzing COVID-19 associated-IgG/IgM. Test were performed at time 0 and after 14 days; Rt-PCR and CLIA assays were also perfoRmed in positive Viva-DiagTM cases. 606 and 393 HCW had blood sample taken at time 0 and 14, respectively. Results Overall, 9 HCW (1.5%) resulted not-negative at Viva-DiagTM and one of them was confirmed positive for SARS-COV2 infection at RT-PCR oropharingeal swab. At time 0, all 9 cases showed some IgM expression and only one IgG; after 14 days IgM persisted in all cases while IgG became evident in 4 ones. A parallel CLIA test was performed in 23 quaratined subjetcs and in all Viva-Diag not negative cases. CLIA confirmed a positive level of IgM in 5/13 positive Viva-Diag cases; conversely, IgG was confirmed positive at CLIA in 4/5 cases positive at Viva-Diag. These results pose the question of different performances of the two tests. Conclusions Our study suggest that Viva-Diag assay can be of help in individualizing SARS_COV2 infected people fisrt of all in cohorts of subjetcs with high prevalence. Different performances of serological colorimetric and CLIA tools remain to be ascertained.