ABSTRACT
OBJECTIVE: The objective of this study was to evaluate the performance of seven antigen rapid diagnostic tests (Ag RDTs) in a clinical setting to identify those that could be recommended for use in the diagnosis of SARS-CoV-2 infection in Uganda. METHODS: This was a cross-sectional prospective study. Nasopharyngeal swabs were collected consecutively from COVID-19 PCR positive and COVID-19 PCR negative participants at isolation centers and points of entry, and tested with the SARS-CoV-2 Ag RDTs. Test sensitivity and specificity were generated by comparing results against qRT-PCR results (Berlin Protocol) at a cycle threshold (Ct) cut-off of ≤39. Sensitivity was also calculated at Ct cut-offs ≤29 and ≤33. RESULTS: None of the Ag RDTs had a sensitivity of ≥80% at Ct cut-off values ≤33 and ≤39. Two kits, Panbio™ COVID-19 Ag and VivaDiag™ SARS-CoV-2 Ag had a sensitivity of ≥80% at a Ct cut-off value of ≤29. Four kits: BIOCREDIT COVID -19 Ag, COVID-19 Ag Respi-Strip, MEDsan® SARS-CoV-2 Antigen Rapid Test and Panbio™ COVID-19 Ag Rapid Test had a specificity of ≥97%. CONCLUSIONS: This evaluation identified one Ag RDT, Panbio™ COVID-19 Ag with a performance at high viral load (Ct value ≤29) reaching that recommended by WHO. This kit was recommended for screening of patients with COVID -19-like symptoms presenting at health facilities.
Subject(s)
COVID-19 , SARS-CoV-2 , Antigens, Viral/analysis , COVID-19/diagnosis , Cross-Sectional Studies , Diagnostic Tests, Routine , Humans , Prospective Studies , Sensitivity and Specificity , Uganda/epidemiologyABSTRACT
INTRODUCTION: Serological testing is needed to better understand the epidemiology of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. Rapid diagnostic tests (RDTs) have been developed to detect specific antibodies, IgM and IgG, to the virus. The performance of 25 of these RDTs was evaluated. METHODS: A serological reference panel of 50 positive and 100 negative plasma specimens was developed from SARS-CoV-2 PCR and antibody positive patients and pre-pandemic SARS-CoV-2-negative specimens collected in 2016. Test performance of the 25 RDTs was evaluated against this panel. RESULTS: A total of 10 RDTs had a sensitivity ≥98%, while 13 RDTs had a specificity ≥98% to anti-SARS-CoV-2 IgG antibodies. Four RDTs (Boson, MultiG, Standard Q, and VivaDiag) had both sensitivity and specificity ≥98% to anti-SARS-CoV-2 IgG antibodies. Only three RDTs had a sensitivity ≥98%, while 10 RDTs had a specificity ≥98% to anti-SARS-CoV-2 IgM antibodies. Three RDTs (Autobio, MultiG, and Standard Q) had sensitivity and specificity ≥98% to combined IgG/IgM. The RDTs that performed well also had perfect or almost perfect inter-reader agreement. CONCLUSIONS: This evaluation identified three RDTs with a sensitivity and specificity to IgM/IgG antibodies of ≥98% with the potential for widespread antibody testing in Uganda.
Subject(s)
COVID-19 , SARS-CoV-2 , Academies and Institutes , Antibodies, Viral , Diagnostic Tests, Routine , Humans , Immunoglobulin M , Sensitivity and Specificity , Uganda/epidemiologyABSTRACT
OBJECTIVES: There is a high demand for SARS-CoV-2 testing to identify COVID-19 cases. Real-time quantitative PCR (qRT-PCR) is the recommended diagnostic test but a number of constraints prevent its widespread implementation, including cost. The aim of this study was to evaluate a low cost and easy to use rapid antigen test for diagnosing COVID-19 at the point of care. METHODS: Nasopharyngeal swabs from suspected COVID-19 cases and low-risk volunteers were tested with the STANDARD Q COVID-19 Ag Test and the results were compared with the qRT-PCR results. RESULTS: In total, 262 samples were collected, including 90 qRT-PCR positives. The majority of samples were from males (89%) with a mean age of 34 years and only 13 (14%) of the positives were mildly symptomatic. The sensitivity and specificity of the antigen test were 70.0% (95% confidence interval (CI): 60-79) and 92% (95% CI: 87-96), respectively, and the diagnostic accuracy was 84% (95% CI: 79-88). The antigen test was more likely to be positive for samples with qRT-PCR Ct values ≤29, with a sensitivity of 92%. CONCLUSIONS: The STANDARD Q COVID-19 Ag Test performed less than optimally in this evaluation. However, the test may still have an important role to play early in infection when timely access to molecular testing is not available but the results should be confirmed by qRT-PCR.