COVID-19 SCREENING AND MONITORING OF ASYMPTOMATIC HEALTH WORKERS WITH A RAPID SEROLOGICAL TEST

BackgroundHealth workers are at high risk for SARS-CoV-2 infection and, if asymptomatic, for transmitting the virus on to fragile cancer patients. Materials and methodWe 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. ResultsOverall, 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. ConclusionsOur 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.

RAPID SEROLOGICAL TESTS HAVE A ROLE IN ASYMPTOMATIC HEALTH WORKERS COVID-19 SCREENING

Health workers are at high risk for SARS-CoV-2 infection and, if asymptomatic, for transmitting the virus on to fragile cancer patients. We screened 525 health workers of our Cancer Institute with rapid serological test Viva-Diag analyzingCOVID-19 associated-IgG/IgM. Six subjects (1,1%) resulted with Viva-Diag test not-negative for IgM. All 6 cases had RT-PCR SARS-CoV-2 test negative; repeating analysis ofIgG/IgM expression by CLIA assay also, 2 cases resulted IgM positive and 1 case IgG/IgM positive. This latter subject reported a contact with an infected SARS-CoV-2 person, a month earlier.In conclusion our study seems to suggest: a) a different analytical sensitivity inIgG/IgM evaluation for Viva-Diag and CLIA assays needing to be further determined; b) the ability of Viva-Diagrapid COVID-19 test to evidence health workers positive for Immunoglobulins expression. Discordant results of rapid serological tests with respect to RT-PCR stress the different clinical meaning the two assays can have, question clearly referring to further studies to optimize the utilization of rapid serological test in asymptomatic subjects at high risk for infection.

Clinical meanings of rapid serological assay in patients tested for SARS-Co2 RT-PCR

BackgroundRT-PCR test for identification of viral nucleic acid is the current standard diagnostic method for the diagnosis of COVID-19 disease but technical reasons limit the utilization of this assay onlarge scalescreenings. MethodWe verified in a consecutive series of 191 symptomatic patients the clinical information that new rapid serological colorimetric test qualitatively analyzing IgM/IgG expression can provide with respect to standard assay and with respect to clinical outcome of patients. ResultsRapid serological test showed a sensitivity of 30% and a specificity of 89% with respect to the standard assay but, interestingly, these performances improve after 8 days of symptoms appearance. After 10 days of symptoms the predictive value of rapid serological test is higher than that of standardassay. When the behaviour of the two immunoglobulins was evaluated with respect to time length of symptoms appaerance, no significant difference in immunoglobulins behaviour was shown. ConclusionsThe rapid serological test analyzed in the present study is candidate to provide information on immunoreaction of the subject to COVID-19 exposure.