ABSTRACT
Introduction: during the current SARS-CoV-2 pandemic phase, the use of rapid diagnostic devices outside the laboratory has expanded enormously, creating great opportunities but also new risks. Methods: the present observational study evaluated the type and frequency of errors of the extra-analytical phases through an active search on all unclear or ambiguous cases. 252 241 rapid antigenic tests performed outside the laboratory in different health facilities over a 132-day period were considered. The requests, the patient demographics and the results were later entered manually onto the Laboratory Information System (LIS). Results: through a number of data checks and internal reports, 2 556 cases of errors in the pre-examination phase were recorded, with a relative frequency of 12,274 parts per million (ppm). The vast majority of errors were observed in this phase;these were due mainly to computer communication problems induced by human errors that made the loading of results or the issuing of the reports difficult. The remaining cases involving erroneous personal data or patient identification amounted to 16 (64 ppm), confirming the relative safety of this phase in decentralized analysis. The errors identified in the post-examination phase were 540, with a relative frequency of 2140 ppm. The assessment of the severity of the errors with Failure Mode and Effect Analysis (FMEA) allowed us to identify in particular, the attribution of the report to the wrong person (20 ppm) and the manual transcription of an incorrect result (20 ppm). Discussion: this study contributes to the comprehension of the critical issues connected to the Point of Care Testing and made it possible to establish corrective actions: improving staff training, choice of instruments with reading devices and establishing direct computer connection for the entering of the requests and results to the LIS.
ABSTRACT
Background. In this study SARS-CoV-2 serology was investigated, using two different ELISA assay, in a cohort of subjects convalescing after COVID-19 recruited for the establishment of a hyperimmune plasma bank. Methods. SARS-CoV-2 serology was investigated in 326 subjects using two commercial ELISA methods: CLIA, MAGLUMI 2019-nCoV IgG CLIA and DiaSorin LIAISON SARS-CoV-2 S1/S2 IgG. Results. Using the MAGLUMI IgG assay 56 subjects 17% were negative and using the SORIN IgG assay 43 subjects (13%) were negative too. MAGLUMI IgG test and the SORIN IgG test showed an good agreement (Cohen's K index = 0.65). Conclusions. Among 326 subjects evaluated after a microbiologically confirmed symptomatic COVID-19 disease in a not negligible number of subject was impossible to demonstrate a humoral immune response In our experience, the MAGLUMI and SORIN tests have shown good agreement in identifying subjects with IgG antibodies to SARS-CoV-2. However, the quantitative response appears to be very little comparable. Moreover results obtained in this study further underline the need for an evaluation of the pre-analytical, analytical conditions and post-analytical and the need for better standardization and harmonization of diagnostic serological tests for SARS-CoV-2.
ABSTRACT
Background: In this study SARS-CoV-2 serology was investigated, using three different methods, in a cohort of convalescent patients from SARS-CoV-2 infection, recruited for the establishment of a hyperimmune plasma bank. Methods: SARS-CoV-2 serology was investigated in 326 subjects using three commercial methods: MAGLUMI (MAG) 2019-nCoV IgM CLIA, MAGLUMI 2019-nCoV IgG CLIA and DiaSorin (SOR) LIAISON SARS-CoV-2 S1/S2 IgG. Moreover, 143 subjects were tested using a plaque reduction micro neutralization assay. Results: MAG IgG test and SOR IgG test showed a good agreement (Cohen's K index = 0.65, CI 95% 0.55 - 0.78). Considering SOR IgG test versus micro neutralization test, the observed cut-off values were: 85 AU/mL for a neutralizing titer of 1/80;108 AU/mL for 1/160 titer and 144 AU/mL for 1/320 titer. Considering MAG IgG test versus micro neutralization test, the observed cut-off values were: 4 AU/mL for a neutralizing titer of 1/80, 5 AU/mL for 1/160 titer and 7 AU/mL for 1/320 titer. Conclusions: In our experience, the MAG and SOR tests showed good agreement in identifying subjects with IgG antibodies to SARS-CoV-2. Obtained results confirmed a good correlation between the antibody concentration detected by the SOR IgG and the neutralizing titer determined by the plaque reduction test.
ABSTRACT
Background The role of the immune response to SARSCoV-2 infection is not yet well known, in particular about the persistence of circulating antibodies. The aim of the study is to assess the time course of the IgM and IgG response. Methods We conducted a study on 123 specimens of 62 subjects with disease confirmed by laboratory tests (time from the onset of symptoms from 3 to 110 days). Both IgM and IgG were measured with a chemiluminescence immunoassay (MAGLUMI 2019-nCoV IgM and MAGLUMI 2019-nCoV IgG respectively) on the Maglumi 800 Analyzer (Snibe, Shenzen, China) according to the manufacturer's instructions. Results The case study was subdivided into 8 groups (≤10 days from the onset of symptoms, 11-13 days, 14-17, 18-21, 22-28, 30-43, 46-71 and 72-110). The clinical sensitivity of IgG rose from 52.9% to 100% after 18 days, and then remained constant. The sensitivity of IgM rose from 35.3% up to about 78.6% at 20 days, then fell to about 27% after 80 days. Considering the concentrations in the samples, after a rapid increase up to about 20 days, we can see a subsequent decrease of the mean concentrations of both IgM and IgG levels. The quantitative comparison of the different classes showed significantly higher IgG concentrations in the days from 14 to 28 compared to both the first two groups and the groups after 46 days (Kruskall-Wallis test p=0.000001). As for the IgM, the trend is similar to that found for IgG, but the differences between groups were lower (Kruskall-Wallis test p=0.0022) and the absolute concentrations were about one order of magnitude smaller. Discussion The persistence of antibodies against SARS-CoV-2 is not known. Studies on the immune response to other coronaviruses showed that the concentrations of IgG decline after few months from the onset of symptoms, although the positivity rate remained relatively stable over a longer period. In the present study, the results seems to confirm this trend. In fact, although the positivity rates did not fall below 100%, in the class with specimens from 72 to 110 days after the onset of symptoms the median IgG concentrations were less than 10% compared to the levels found after 15-20 days. Conclusion The antibodies titre in patients exposed to COVID-19 may decrease already after 6-7 weeks after the symptoms' onset.