ABSTRACT
Lateral flow devices are quickly being implemented for use in large scale population surveillance programs for SARS-CoV-2 infection in the United Kingdom. These programs have been piloted in city wide screening in the city of Liverpool, and are now being rolled out to support care home visits and the return home of University students for the Christmas break. Very little data exists comparing the performance of the UK lateral flow tests with gold standard PCR diagnostics, especially against comparable test populations such as the national Pillar 2 testing program in the United Kingdom. Here we utilise thousands of pillar 2 test data from our University of Birmingham test lab, and by extrapolation against the validate limit-of-detection of the lateral flow assay, provide a potential sensitivity for the test in a comparable low prevalence population captured in the pillar 2 program. Our data suggests the lateral flow assay should successfully capture around 85% of all PCR positive tests performed in our pillar 2 laboratory, and that a fully designed comparative study of lateral flow versus PCR testing is merited in a real life testing environment
Subject(s)
COVID-19ABSTRACT
ObjectivesTo assess the accuracy and completeness of information provided by websites selling home self-sampling and testing kits for COVID-19. DesignCross-sectional observational study. SettingAll websites (n = 27) selling direct to user home self-sampling and testing for COVID-19 (41 tests) in the UK (39 tests) and US (2 tests) identified by a website search on 23rd May 2020. Main outcome measuresThirteen predefined basic information items to communicate to a user, including who should be tested, when and how testing should be done, test accuracy, and interpretation of results. ResultsMany websites did not provide the name or manufacturer of the test (32/41; 78%), when to use the test (10/41; 24%), test accuracy (12/41; 29%), and how to interpret results (21/41; 51%). Sensitivity and specificity were the most commonly reported test accuracy measures (either reported for 27/41 (66%) tests); we could only link these figures to manufacturers documents or publications for four (10%) tests. Predictive values, most relevant to users, were rarely reported (five [12%] tests reported positive predictive values). For molecular virus tests, 9/23 (39%) websites explained that test positives should self-isolate, and 8/23 (35%) explained that test negatives may still have the disease. For antibody tests, 12/18 (67%) websites explained that testing positive does not necessarily infer immunity from future infection. Seven (39%) websites selling antibody tests claimed the test had a CE mark, when they were for a different intended use (venous blood rather than finger-prick samples). ConclusionsAt the point of online purchase of home self-sampling COVID-19 tests, users in the UK are provided with incomplete, and in some cases misleading information on test accuracy, intended use and test interpretation. Best practice guidance for communication about tests to the public should be developed and enforced for online sales of COVID-19 tests. Strengths and WeaknessesO_LIWe believe this is the first research on accuracy of information provided by websites selling tests for COVID-19, where users may put themselves or others at increased risk of transmission if results are misinterpreted. C_LIO_LIWe duplicated processes of searching and data extraction to minimise bias C_LIO_LIUsing pre-specified criteria, we found evidence that websites selling home self-sampling COVID-19 tests provided incomplete and inaccurate information on test accuracy and interpretation of test results at the point of purchase. C_LIO_LIWe developed basic guidance on what should be communicated when selling tests, including the type of test; situations when the test should be used; the time when the test should be done and details of how it should be done; the name of the test and details from clinical accuracy studies; evidence of compliance with regulatory approvals; explanation of test results using accessible and relevant metrics such as predictive values; and guidance to the interpretation and actions based on results. C_LIO_LIWe only included websites from the UK and US, so whilst the principles of what should be communicated apply to all countries, the results about data completeness are not generalisable beyond the UK and US. C_LI