ABSTRACT
Intro: In Australia, the main methods to diagnose COVID-19 are through rapid antigen tests (RATs) and through nucleic acid amplification testing (NAAT, including polymerase chain reaction) on healthcare worker (HCW)-collected combined nose/throat swabs. With self-collection widely used by the public for RATs, the aim of this study was to evaluate the performance of self-collected samples using commercial NAAT for SARS-CoV-2. Method(s): Consenting participants aged 14 years and older were provided with a self-collection pack containing instructions and either a FLOQSwab (Copan) or a Rhinoswab (Rhinomed). Participants collected their own nasal sample unsupervised prior to having a HCW-collected combined nose and throat swab taken for standard of care NAAT. Paired self-collected and HCW samples were tested on the cobas SARS-CoV-2 assay (Roche) and the Aptima SARS-CoV-2 assay (Hologic). Finding(s): We demonstrated comparable sensitivity, specificity, and agreement between self-collected nasal and Rhinoswab samples, compared to HCW- collected samples tested using the cobas SARS-CoV-2 and Aptima SARS-CoV-2 assays. In our study the clinical performance of self-collected specimens was comparable to HCW-collected samples, with both self-collect nasal and Rhinoswab samples resulting in 90-95% sensitivity, and in most cases >95% specificity. Discussion(s): Without the availability of samples for NAAT the ability to perform genomic testing is limited, reducing surveillance and public health investigations. We showed that genomic sequencing from self-collected samples can correctly identify the virus lineage and that the main determination of successful genomic testing is a high viral load rather than collection method. Conclusion(s): These data support self-collection as an accessible method for community testing for COVID-19 and introduces a novel collection device, the Rhinoswab as an alternative to the standard nasal swab. The testing method of self-collection can be expanded from the widely used RATs to NAAT and genomic testing which may inform the management and public health response to the COVID-19 pandemic.Copyright © 2023
ABSTRACT
Intro: Uptake of SARS-CoV-2 rapid antigen tests (RATs) for self-testing has been high following authorisation by the Australian Therapeutic Goods Administration (TGA). However, there are no published Australian data assessing feasibility and compliance with home-based rapid antigen testing. The aim of this study was to determine the acceptability of daily rapid antigen self-testing. Method(s): We prospectively recruited a cohort of hospital employees and students from primary and secondary school to perform daily self-testing using RATs in the home over 14 consecutive days. Participants consenting to the study were supplied with 15 Roche SARS-CoV-2 Antigen Nasal Self Tests, 3 saliva swabs for self-collection for RT-PCR and were asked to record results and answer a daily survey using a smartphone application. Finding(s): 38% (26/68) of the cohort were compliant to 14 consecutive days of testing;this was significantly higher in students (71%) than hospital employees (28%). The median number of tests performed over 14 consecutive days was 11 and time to first missed test was a median 5.5 days. The most common reasons for missing days were "I forgot" (37.5%) and "too busy" (8.9%). Ease of self- nasal swabbing, self-nasal testing. performing the test and using the app were rated as comfortable/very comfortable in over 80% of the cohort. Discussion(s): Most study participants in this Australian cohort were compliant with frequent home-based RATs. By study end most participants (93.8%) found the testing process acceptable/very acceptable. There is need for further work on the cost-effectiveness and impact of self-tested RATs under a range of specific uses and conditions. Conclusion(s): This study provided valuable information on acceptability and feasibility of regular home-based testing which could be applied to other diseases. Ongoing community engagement with clear information on RATs including accuracy and use cases is important for decision-making and addressing concerns, particularly for linguistically diverse peoples.Copyright © 2023
ABSTRACT
Serological assays for SARS-CoV-2 infection are now widely available for use in diagnostic laboratories. Limited data are available on the performance characteristics in different settings, and at time periods remote from the initial infection. Validation of the Abbott (Architect SARS-CoV-2 IgG), DiaSorin (Liaison SARS-CoV-2 S1/S2 IgG) and Roche (Cobas Elecsys Anti-SARS-CoV-2) assays was undertaken utilising 217 serum samples from 131 participants up to 7 months following COVID-19 infection. The Abbott and DiaSorin assays were implemented into routine laboratory workflow, with outcomes reported for 2764 clinical specimens. Sensitivity and specificity were concordant with the range reported by the manufacturers for all assays. Sensitivity across the convalescent period was highest for the Roche at 95.2-100% (95% CI 81.0-100%), then the DiaSorin at 88.1-100% (95% CI 76.0-100%), followed by the Abbott 68.2-100% (95% CI 53.4-100%). Sensitivity of the Abbott assay fell from approximately 5 months; on this assay paired serum samples for 45 participants showed a significant drop in the signal-to-cut-off ratio and 10 sero-reversion events. When used in clinical practice, all samples testing positive by both DiaSorin and Abbott assays were confirmed as true positive results. In this low prevalence setting, despite high laboratory specificity, the positive predictive value of a single positive assay was low. Comprehensive validation of serological assays is necessary to determine the optimal assay for each diagnostic setting. In this low prevalence setting we found implementation of two assays with different antibody targets maximised sensitivity and specificity, with confirmatory testing necessary for any sample which was positive in only one assay.