Rapid Serological Tests for SARS-CoV-2: Diagnostic Performance of 4 Commercial Assays.

OBJECTIVE: To assess the diagnostic performance of lateral flow immunochromatographic assays (LFAs) of 4 different manufacturers to identify SARS-CoV-2 antibodies (IgM, IgG, or total), comparing them with the nucleic acid amplification test (NAAT) or the clinical defined test (definite or probable SARS-CoV-2 infection, respectively). METHODS: One hundred nineteen serum samples were randomly selected by convenience and distributed in the following groups: (1) group with SARS-CoV-2 infection (n = 82; RT-qPCR positive [definite, n = 70] and probable [n = 12]); (2) other diseases (n = 27; other viruses identified [n = 8] and SARS of other etiologies [n = 19]); and (3) healthy control group (n = 10). LFAs of 4 manufacturers were compared: MedTest Coronavirus (COVID-19) IgG/IgM (MedLevensohn, Brazil); COVID-19 IgG/IgM ECO Test (Ecodiagnóstica, Brazil); Camtech COVID-19 IgM/IgG Rapid Test Kit (Camtech Diagnostics Pte Ltd, Singapore); and 1-Step COVID-19 Test for total antibodies (Guangzhou Wondfo Biotech Co., China). RESULTS: The 4 tests studied showed high diagnostic performance characteristics for the diagnoses of definite or probable SARS-CoV-2 infection. The best measures were for the Wondfo test: sensitivity (86.59%; 95% CI: 77.26-93.11%), specificity (100%; 90.51-100%), DOR (257; 60-1,008), LR+ (33.43; 4.82-231.85), LR- (0.13; 0.08-0.23), accuracy (90.76%; 84.06-95.29%), and Matthews correlation coefficient (MCC) 0.82. Although considering only the probable SARS-CoV-2 infection (PCR-) cases, all the kits studied showed limited values. CONCLUSION: Our data demonstrate the excellent performance of LFA for the diagnoses of definite or probable SARS-CoV-2 infection. There was substantial heterogeneity in sensitivities of IgM and IgG antibodies among the different kits. LFA tests cannot replace molecular diagnostics but should be used as an additional screening tool.

Assessing the impact of the Gamma variant on COVID-19 patient admissions in a southern Brazilian tertiary hospital-A comparison of dual pandemic phases.

Since the first case of COVID-19, Brazil has undergone infection waves with distinct characteristics. The description of new variants has alerted the emergence of more contagious or virulent viruses. The variant of concern Gamma emerged in Brazil and caused an epidemic wave, but its spread outside the country was limited. We report the clinical-epidemiological profile of hospitalized patients with COVID-19 by comparing two periods. A retrospective cohort study was performed. The primary outcome was to assess individuals with COVID-19 admitted in wards and intensive care units at the academic hospital of the Federal University of Parana (CHC-UFPR) between March 2020 and July 2021, correlating demographic, clinical-epidemiologic, and survival data with the most prevalent viral variant found in each period. We used Kaplan-Meier analysis to estimate the probability of survival and ROC curves to evaluate laboratory tests to find a cutoff point for poor outcomes. Data from 2,887 individuals were analyzed, 1,495 and 1,392 from the first and second periods, respectively. Hospitalization predominated among males in both periods, and the median age was significantly lower in the second one. The frequency of comorbidities was similar. Various demographic factors, clinical assessments, and laboratory tests were examined in relation to greater severity. When comparing the two periods, we observed predominance of the Wild virus during the first wave and the Gamma variant during the second, with no significant difference in outcomes. The findings suggest that despite the association of many factors with increased severity, the temporal variation between the two periods did not result in a notable divergence in the measured outcomes. The COVID-19 pandemic has lasted for a long time, with periods marked by peaks of cases, often caused by the emergence of viral variants, resulting in higher infection rates and rapid dissemination but, for variant Gamma, no apparent greater virulence.