SARS-CoV-2 rapid antigen test in comparison to RT-PCR targeting different genes: A real-life evaluation among unselected patients in a regional hospital of Italy.

We assessed the performance of the Panbio rapid antigen detection (RAD) test for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and we compared it with the routine reverse transcriptase-polymerase chain reaction (RT-PCR)-based molecular test in a population of 4167 unselected patients admitted to IRCCS Sacro Cuore Don Calabria Hospital. Analysis stratified by cycling threshold (Ct ) value of SARS-CoV-2 gene targets indicated that antigen (Ag)-positive Ct values were significantly lower compared to Ag-negative values (p < 0.0001). Overall, we found discordance in 140, tested negative by RAD and positive by RT-PCR, and in 4 resulted positive by RAD and negative by RT-PCR. RAD test achieved a sensitivity and specificity of 66.82% and 99.89%, respectively. The positive predictive value was shown to be 97.87% while the negative predictive value was shown to be 97.62%. In our context, the RAD test showed a reliable diagnostic response in subjects that displayed high Ct values, corresponding to high viral load, while low ability was displayed to identify positive cases with medium-low Ct values, thus presenting low viral load and where confirmatory RT-PCR was needed. Our finding supports the use of the RAD test in real-life settings where a high volume of swabs is being processed but with caution when interpreting a positive test result in a low prevalence setting.

A Seroprevalence Study of Anti-SARS-CoV-2 Antibodies in Patients with Inflammatory Bowel Disease during the Second Wave of the COVID-19 Pandemic in Italy.

Background and Objectives: Studies have shown a lower prevalence of anti-SARS-CoV-2 antibodies in patients with inflammatory bowel disease (IBD), including amongst those receiving biological therapy. Aims were to determine the seroprevalence of anti-SARS-CoV-2 antibodies in IBD patients and to assess any association between seropositivity and IBD characteristics. Materials and Methods: Serum from adult IBD patients was prospectively collected between December 2020 and January 2021 and analyzed for anti-SARS-CoV-2 antibodies. Information about IBD characteristics and SARS-CoV-2 exposure risk factors was collected and analyzed. Serum from non-IBD healthcare workers formed the control group. Results: 311 IBD patients on biologics and 75 on mesalazine were enrolled. Ulcerative colitis (UC) extension (p < 0.001), Crohn's disease (CD) phenotype (p = 0.009) and use of concomitant corticosteroids (p < 0.001) were significantly different between the two IBD groups. Overall seroprevalence among IBD patients was 10.4%. The control group showed a prevalence of 13.0%, not significantly different to that of IBD patients (p = 0.145). Only a close contact with SARS-CoV-2 positive individuals and the use of non-FFP2 masks were independently associated with a higher likelihood of seropositivity amongst IBD patients. Conclusion: In IBD patients, the prevalence of anti-SARS-CoV-2 antibodies is not determined by their ongoing treatment. Disease-related characteristics are not associated with a greater risk of antibody seropositivity.