Evaluation of SARS-CoV-2 Antibody Point of Care Devices in the Laboratory and Clinical Setting

SARS-CoV-2 Antibody tests have been marketed to diagnose previous SARS-CoV-2 infection and as a test of immune status. There is a lack of evidence on the performance and clinical utility of these tests. We aimed to carry out an evaluation of 14 point of care (POC) SARS-CoV-2 antibody tests. Serum from participants with previous RT-PCR (Real-Time Polymerase chain reaction) confirmed SARS-CoV-2 infection and pre-pandemic controls were used to determine specificity and sensitivity of each POC device. Changes in sensitivity with increasing time from infection were determined on a cohort of participants. Corresponding neutralising antibody status was measured to establish whether the detection of antibodies by the POC device correlated with immune status. Paired capillary and serum samples were collected to ascertain whether POC devices performed comparably on capillary samples. Sensitivity and specificity varied between the POC devices and in general did not meet the manufacturers reported performance characteristics signifying the importance of independent evaluation of these tests. The sensitivity peaked at >20 days following symptoms onset however sensitivity of 3 POC devices evaluated at extended time points showed that sensitivity declined with time and this was particularly marked at >140 days post infection onset. This is relevant if the tests are to be used for sero-prevelence studies. Neutralising antibody data showed positive antibody results on POC devices did not necessarily confer high neutralising antibody titres and these POC devices cannot be used to determine immune status to the SARS-CoV-2 virus. Comparison of paired serum and capillary results showed that there was a decline in sensitivity using capillary blood. This has implications in the utility of the test as they are designed to be used on capillary blood by the general population.

Serological co-infection of dengue and COVID-19: case series in Bangladesh

Parallel symptoms and laboratory findings between dengue and coronavirus disease 2019 (COVID-19) pretense a diagnostic contest in some dengue-endemic countries in Asia. In this study, we described ten cases of suspected COVID-19-dengue co-infection in a tertiary care hospital in Bangladesh. Serological data showed that patients with positive results for dengue virus (DENV) NS1 antigen and anti-dengue IgG and IgM were also reactive to COVID-19 rapid antibody tests, suggesting dengue with COVID-19 coinfection. The present study indicated a public health concern regarding COVID-19 and dengue detection in Bangladesh as well as in other dengue-endemic countries and it was important for these nations to manage both pathogens concurrently.

Diagnostic Accuracy of COVID-19 Antibody Tests Authorized by FDA Philippines: A Systematic Review and Meta-Analysis

Introduction: Coronavirus Disease (COVID-19) is a highly infectious disease caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) which has infected many people all over the world. One of the best ways to lessen its spread is through early detection and diagnosis. Various serological tests are now being used as a surveillance tool in the detection of antibodies as a response to SARS-CoV-2. The aim of this study is to evaluate the diagnostic accuracy and performance of the available COVID-19 antibody tests authorized by the Food and Drug Administration (FDA) Philippines that make use of Enzyme-Linked Immunosorbent Assay (ELISA), Chemiluminescence Immunoassay (CLIA) and Lateral Flow Immunoassay (LFIA). Method: Complete published journal articles relevant to the diagnostic accuracy of the three antibody tests were collected using trusted medical journal search engines. The quality of journals was assessed using QUADAS-2 to determine the risk of bias and assess the applicability judgments of diagnostic accuracy studies. Forest plots were used to summarize the performance of LFIA, ELISA and CLIA according to their specificity and sensitivity in detecting various antibodies. Pooled sensitivity and specificity were also done using bivariate random-effects models with its log-likelihood, a corresponding chi-square test statistic, and area under the summary Receiver-Operating Characteristic curve to see the potential heterogeneity in the data and to assess the diagnostic accuracy of the COVID-19 antibody tests. Results: Bivariate random-effects model and areas under the sROC curve were used to evaluate the diagnostic accuracy of COVID-19 antibody tests. The pooled sensitivity in detecting IgG based on CLIA, ELISA, and LFIA were 81.7%, 58.7%, and 74.3% respectively, with an overall of 72.0%. For IgM detection, LFIA has a higher pooled sensitivity of 69.6% than CLIA with 61.0%. Overall, the pooled sensitivity is 68.5%. In IgA detection, only ELISA based test was included with a pooled sensitivity of 84.8%. Lastly, pooled sensitivities for combined antibodies based on ELISA and LFIA were 89.0% and 81.6% respectively, with an overall of 82.5%. On the other hand, all tests excluding ELISA-IgA displayed high pooled specificities with a range of 94.0% to 100.0%. Diagnostic accuracies of the test in detecting IgG, IgM, and combined antibodies were found out to be almost perfect based on the computed area under the sROC with values of 0.973, 0.953, and 0.966, respectively. Conclusion: In this systematic review and meta-analysis, existing evidence on the diagnostic accuracy of antibody tests for COVID-19 were found to be characterized by high risks of bias, consistency in the heterogeneity of sensitivities, and consistency in the homogeneity of high specificities except in IgA detection using ELISA. The bivariate random-effects models showed that there are no significant differences in terms of sensitivity among CLIA, ELISA and LFIA in detecting IgG, IgM, and combined antibodies at a 95% confidence interval. Nonetheless, CLIA, ELISA and LFIA were found to have excellent diagnostic accuracies in the detection of IgG, IgM and combined antibodies as reflected by their AUC values. Doi: 10.28991/SciMedJ-2021-0304-1 Full Text: PDF

Routine COVID-19 testing may not be necessary for most cancer patients

Cancer patients are at risk for severe complications or death from COVID-19 infection. Therefore, the need for routine COVID-19 testing in this population was evaluated. Between 1st August and 30th October 2020, 150 cancer patients were included. Symptoms of COVID-19 infection were evaluated. All eligible individuals went through RT-PCR and serological tests for COVID-19. At the same time, 920 non-cancer patients were recruited from a random sample of individuals who were subject to routine molecular and anti-body screening tests. Of 150 cancer patients, 7 (4.7%) were RT-PCR positive. Comorbidity made a significant difference in the RT-PCR positivity of cancer patients, 71.4% positive versus 25.8% negative (P-value = 0.02). The average age for negative and positive groups was 53.3 and 58.2 respectively (P-value = 0.01). No significant difference was observed between cancer and non-cancer patients regarding COVID-19 antibody tests. However, cancer patients were 3 times less likely to have a positive RT-PCR test result OR = 0.33 (CI: 0.15–0.73). The probability of cancer patients having a positive routine test was significantly lower than non-cancer patients, and the concept that all cancer patients should be routinely tested for COVID-19 may be incorrect. Nevertheless, there may be a subgroup of patients with comorbidities or older age who may benefit from routine COVID-19 testing. Importantly, these results could not be subjected to multivariate analysis.

Is cardiac involvement prevalent in highly trained athletes after SARS-CoV-2 infection? A cardiac magnetic resonance study using sex-matched and age-matched controls

ObjectivesTo investigate the cardiovascular consequences of SARS-CoV-2 infection in highly trained, otherwise healthy athletes using cardiac magnetic resonance (CMR) imaging and to compare our results with sex-matched and age-matched athletes and less active controls.MethodsSARS-CoV-2 infection was diagnosed by PCR on swab tests or serum immunoglobulin G antibody tests prior to a comprehensive CMR examination. The CMR protocol contained sequences to assess structural, functional and tissue-specific data.ResultsOne hundred forty-seven athletes (94 male, median 23, IQR 20–28 years) after SARS-CoV-2 infection were included. Overall, 4.7% (n=7) of the athletes had alterations in their CMR as follows: late gadolinium enhancement (LGE) showing a non-ischaemic pattern with or without T2 elevation (n=3), slightly elevated native T1 values with or without elevated T2 values without pathological LGE (n=3) and pericardial involvement (n=1). Only two (1.4%) athletes presented with definite signs of myocarditis. We found pronounced sport adaptation in both athletes after SARS-CoV-2 infection and athlete controls. There was no difference between CMR parameters, including native T1 and T2 mapping, between athletes after SARS-CoV-2 infection and the matched athletic groups. Comparing athletes with different symptom severities showed that athletes with moderate symptoms had slightly greater T1 values than athletes with asymptomatic and mildly symptomatic infections (p<0.05). However, T1 mapping values remained below the cut-off point for most patients.ConclusionAmong 147 highly trained athletes after SARS-CoV-2 infection, cardiac involvement on CMR showed a modest frequency (4.7%), with definite signs of myocarditis present in only 1.4%. Comparing athletes after SARS-CoV-2 infection and healthy sex-matched and age-matched athletes showed no difference between CMR parameters, including native T1 and T2 values.

Assessment of the Field Utility of a Rapid Point-of-Care Test for SARS-CoV-2 Antibodies in a Household Cohort

Point-of-care (POC) tests to detect SARS-CoV-2 antibodies offer quick assessment of serostatus after natural infection or vaccination. We compared the field performance of the BioMedomics COVID-19 IgM/IgG Rapid Antibody Test against an ELISA in 303 participants enrolled in a SARS-CoV-2 household cohort study. The rapid antibody test was easily implemented with consistent interpretation across 14 users in a variety of field settings. Compared with ELISA, detection of seroconversion lagged by 5 to 10 days. However, it retained a sensitivity of 90% (160/177, 95% confidence interval [CI] 85–94%) and specificity of 100% (43/43, 95% CI 92–100%) for those tested 3 to 5 weeks after symptom onset. Sensitivity was diminished among those with asymptomatic infection (74% [14/19], 95% CI 49–91%) and early in infection (45% [29/64], 95% CI 33–58%). When used appropriately, rapid antibody tests offer a convenient way to detect symptomatic infections during convalescence.

Durability of SARS-CoV-2 Antibodies from Natural Infection in Children and Adolescents

Background. Recent data suggest the SARS-CoV-2 Delta (B.1.617.2) variant is more transmissible among children compared to the Alpha (B.1.1.7) variant. The true incidence and longitudinal presence of antibody response to SARS-CoV-2 infection is not known, however. We provided estimates of antibody response using Texas Coronavirus Antibody REsponse Survey (Texas CARES) data, a prospective population-based seroprevalence project designed to assess antibody status over time among the general population throughout the state. Methods. In October 2020 Texas CARES began enrolling adults (aged 20-80 years) and children (aged 5-19 years). Participants were offered a series of three SARS-CoV-2 antibody tests over 6-8 months, or every 2-3 months that includes the immunoassay for detection of antibodies to the SARS-CoV-2 nucleocapsid protein (Roche N-test). Descriptive characteristics and COVID-19 infection-related symptom status was determined by questionnaire at the time of enrollment and prior to each successive blood draw. This analysis included participants ages 5-to-19 years old who have completed all three antibody assessments. Results. From our sample (n=159; mean age 12.5 years, SD 3.6), 96% of those with evidence of nucleocapsid antibodies at baseline assessment continued to have antibodies > six months later (mean 7.0 months, SD 0.97). There was no difference in the presence of antibodies by symptom status (asymptotic versus symptomatic) or severity (mild-moderate versus severe), sex, age group, or body mass index group (underweight, healthy weight, overweight, obesity) over the three antibody measurement timepoints. Conclusions. These results suggest that infection-induced antibodies persist and thus may provide some protection against future infection for at least half a year. 57.9% of the sample were negative for infection-induced antibodies at their third measurement point, suggesting a significant proportion of children have still not acquired natural infection.

Tandem Use of OvMANE1 and Ov-16 ELISA Tests Increases the Sensitivity for the Diagnosis of Human Onchocerciasis

The current serological test for human onchocerciasis relies on IgG4 reactivity against the parasite Ov-16 antigen, with reported sensitivities of only 60–80%. As control programs move from control to elimination, it is imperative to identify novel molecules that could improve the serodiagnosis reliability of this disease. In this study we compared the sensitivity of total IgG against OvMANE1—a chimeric antigen previously identified as a potential biomarker of human onchocerciasis—with that of an Ov-16 antibody test to detect an Onchocerca volvulus infection in persons presenting with microfilaria in skin snips. One hundred and ninety serum samples were obtained from persons with epilepsy in an onchocerciasis-endemic area at Ituri in the Democratic Republic of Congo where ivermectin has never been distributed. Fifty-nine (31.1%) samples were from individuals with a positive skin snip test; 41 (69.5%) of these 59 samples were positive with the OvMANE1 test and 41 (69.5%) with the Ov-16 test; 30 (50.8%) samples were positive for both tests and in 52 (88.1%) at least one of the tests was positive. Testing the 131 sera from persons with a negative skin snip result revealed that 63 (48.1%) were positive exclusively with the OvMANE1 test, 13 (9.9%) exclusively with the Ov-16 test and 25 (19.1%) with both tests. Nine European samples from individuals without past travel history in onchocerciasis endemic zones and 15 samples from Rwanda, a hypoendemic country for onchocerciasis were all negative for the OvMANE1 and Ov-16 tests. However, the specificity of both tests was difficult to determine due to the lack of a gold standard for antibody tests. In conclusion, the tandem use of OvMANE1 and Ov-16 tests improves the sensitivity of detecting Onchocerca volvulus seropositive individuals but, the OvMANE1 test needs to be further evaluated on samples from a population infected with other helminths to cautiously address its specificity.