ABSTRACT
We assessed the performance of the CoronaCHEK lateral flow assay on samples from Uganda and Baltimore to determine the impact of geographic origin on assay performance. Plasma samples from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) PCR-positive individuals (Uganda, 78 samples from 78 individuals, and Baltimore, 266 samples from 38 individuals) and from prepandemic individuals (Uganda, 1,077, and Baltimore, 532) were evaluated. Prevalence ratios (PR) were calculated to identify factors associated with a false-positive test. After the first positive PCR in Ugandan samples, the sensitivity was 45% (95% confidence interval [CI], 24,68) at 0 to 7 days, 79% (95% CI, 64 to 91) at 8 to 14 days, and 76% (95% CI, 50 to 93) at >15 days. In samples from Baltimore, sensitivity was 39% (95% CI, 30 to 49) at 0 to 7 days, 86% (95% CI, 79 to 92) at 8 to 14 days, and 100% (95% CI, 89 to 100) at 15 days after positive PCR. The specificity of 96.5% (95% CI, 97.5 to 95.2) in Ugandan samples was significantly lower than that in samples from Baltimore, 99.3% (95% CI, 98.1 to 99.8; P < 0.01). In Ugandan samples, individuals with a false-positive result were more likely to be male (PR, 2.04; 95% CI, 1.03,3.69) or individuals who had had a fever more than a month prior to sample acquisition (PR, 2.87; 95% CI, 1.12 to 7.35). Sensitivity of the CoronaCHEK was similar in samples from Uganda and Baltimore. The specificity was significantly lower in Ugandan samples than in Baltimore samples. False-positive results in Ugandan samples appear to correlate with a recent history of a febrile illness, potentially indicative of a cross-reactive immune response in individuals from East Africa.
Subject(s)
COVID-19 , SARS-CoV-2 , Antibodies, Viral , Female , Humans , Male , Sensitivity and Specificity , UgandaABSTRACT
Early in the SARS-CoV-2 pandemic, convalescent plasma (CP) therapy was proposed as a treatment for severely ill patients. We conducted a CP treatment protocol under the Mayo Clinic Extended Access Program at University Hospital Brooklyn (UHB). Potential donors were screened with a lateral flow assay (LFA) for IgM and IgG antibodies against the SARS-CoV-2 S1 receptor-binding domain (RBD). Volunteers that were LFA positive were tested with an ELISA to measure IgG titers against the RBD. Subjects with titers of at least 1:1024 were selected to donate. Most donors with positive LFA had acceptable titers and were eligible to donate. Out of 171 volunteers, only 65 tested positive in the LFA (38.0%), and 55 (32.2%) had titers of at least 1:1024. Before our donation program started, 31 CP units were procured from the New York Blood Center (NYBC). Among the 31 CP units that were obtained from the NYBC, 25 units (80.6%) were positive in the LFA but only 12 units (38.7%) had titers of at least 1:1024. CP was administered to 28 hospitalized COVID-19 patients. Patients who received low titer CP, high titer CP and patients who did not receive CP were followed for 45 days after presentation. Severe adverse events were not associated with CP transfusion. Death was a less frequent outcome for patients that received high titer CP (>1:1024) 38.6% mortality, than patients that received low titer CP (≤1:1024) 77.8% mortality.