Diagnostic Accuracy of a Rapid SARS-CoV-2 Antigen Test Among People Experiencing Homelessness: A Prospective Cohort and Implementation Study.

INTRODUCTION: Detection strategies in vulnerable populations such as people experiencing homelessness (PEH) need to be explored to promptly recognize severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreaks. This study investigated the diagnostic accuracy of a rapid SARS-CoV-2 Ag test in PEH during two pandemic waves compared with gold standard real-time multiplex reverse transcription polymerase chain reaction (rtRT-PCR). METHODS: All PEH ≥ 18 years requesting residence at the available shelters in Verona, Italy, across two cold-weather emergency periods (November 2020-May 2021 and December 2021-April 2022) were prospectively screened for SARS-CoV-2 infection by means of a naso-pharyingeal swab. A lateral flow immunochromatographic assay (Biocredit® COVID-19 Ag) was used as antigen-detecting rapid diagnostic test (Ag-RDT). The rtRT-PCR was performed with Allplex™ SARS-CoV-2 assay kit (Seegene). Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated as measures for diagnostic accuracy. RESULTS: Overall, 503 participants were enrolled during the two intervention periods for a total of 732 paired swabs collected: 541 swabs in the first period and 191 in the second. No significant differences in demographic and infection-related characteristics were observed in tested subjects in the study periods, except for the rate of previous infection (0.8% versus 8%; p < 0.001) and vaccination (6% versus 73%; p < 0.001). The prevalence of SARS-CoV-2 in the cohort was 8% (58/732 swabs positive with rtRT-PCR). Seventeen swabs were collected from symptomatic patients (7%). Among them, the concordance between rtRT-PCR and Ag-RDT was 100%, 7 (41.2%) positive and 10 negative pairs. The overall sensitivity of Ag-RDT was 63.8% (95% CI 60.3-67.3) and specificity was 99.8% (95% CI 99.6-100). PPV and NPV were 97.5% and 96.8%, respectively. Sensitivity and specificity did not change substantially across the two periods (65.1% and 99.8% in 2020-2021 vs. 60% and 100% in 2021-2022). CONCLUSIONS: A periodic Ag-RDT-based screening approach for PEH at point of care could guide preventive measures, including prompt isolation, without referral to hospital-based laboratories for molecular test confirmation in case of positive detection even in individuals asymptomatic for COVID-19. This could help reduce the risk of outbreaks in shelter facilities.

Impact of Covid-19 pandemic on Ophthalmic Emergency Department in an Italian tertiary eye centre.

PURPOSE: To evaluate the effects of the COVID-19 pandemic on the Ophthalmic Emergency Department (OED) activity of the tertiary eye centre of Verona. METHODS: OED reports of patients visited during lockdown (COVID-period) and in the corresponding period of 2017, 2018 and 2019 (COVID-free period) have been retrieved to draw a comparison. Patients' demographic and clinical data recorded and analysed are the following: age, gender, previous ocular history, aetiology, symptoms onset, type of symptoms, discharge diagnosis, urgency and severity of diagnosis. RESULTS: OED consultations dropped from 20.6 ± 7.3 visits/day of the COVID-free period to 8.6 ± 4.6 visits/day of the COVID-period. In the COVID-period patients waited longer before physically going to the OED, lamented more vision loss and less redness and reported a higher percentage of traumatic events when compared to the COVID-free period. A significant reduction of ocular surface conditions occurred, while vitreo-retinal disorders increased. Overall, both urgency and severity of diagnosed diseases raised significantly in the COVID-period. CONCLUSION: The COVID-19 pandemic drove a significant reduction of the overall OED activity. People with less urgent and milder conditions preferred to wait and endure their ocular discomfort for a few days rather than leaving home and risking to contract the infection. Our analysis highlights how several times the OED is used improperly by patients diagnosed with non-urgent disorders. A more accurate use of the OED would allow a reduction of management costs and the avoidance of overcrowding, which can lead to delays in the care of patients that really need assistance.