BackgroundThe LumiraDx SARS-CoV-2 antigen test, which uses a high-sensitivity, microfluidic immunoassay to detect the nucleocapsid protein of SARS-CoV-2, was evaluated for diagnosing acute COVID-19 in adults and children across point-of-care settings.MethodsTwo paired anterior nasal swabs or two paired nasopharyngeal swabs were collected from each participant. Swabs were tested by the LumiraDx SARS-CoV-2 antigen test and compared with real-time PCR (rt-PCR; Roche cobas 6800 platform). Positive- and negative predictive values and likelihood ratios were calculated. Results stratified based on gender, age, duration of symptoms, and rt-PCR cycle threshold.ResultsOut of the 512 participants, aged 0-90 years, of this prospective validation study, 414 (81%) were symptomatic for COVID-19 and 123 (24%) swabs were positive for SARS-CoV-2 based on rt-PCR testing. Compared with rt-PCR, the 12-minute swab test had 97.6% sensitivity and 96.6% specificity within 12 days of symptom onset, representing the period of infectivity. All (100%) samples detected within 33 rt-PCR cycles were also identified using the antigen test. Results were consistent across age and gender. Despite being performed by minimally trained healthcare workers, the user error rate of the test system was 1%.ConclusionThe rapid high-sensitivity assay using nasopharyngeal or anterior nasal sampling may offer significant improvements for diagnosing acute SARS-CoV-2 infection in clinic- and community-based settings.SummaryA 12-minute nasal swab test detects 97.6% of COVID-19 infections, compared to gold standard real-time PCR testing, up to 12 days following symptom onset using a microfluidic immunoassay for SARS-CoV-2 nucleocapsid protein.

Objectives The World Health Organization (WHO) recommends screening HIV-infected people for cryptococcal antigens to identify cryptococcosis, a major cause of AIDS-related deaths. Since the burden of cryptococcosis is unknown in South Africa’s KwaZulu-Natal province, we assessed the cryptococcal antigenuria prevalence among newly-diagnosed HIV-infected adults. Methods We conducted a cross-sectional study of newly-diagnosed HIV-infected adults who received voluntary HIV testing in an outpatient clinic. Participants provided a urine specimen in a sterile container, and we performed testing with a WHO-endorsed rapid cryptococcal antigen lateral flow assay (Immy Inc., Norman, USA) per manufacturer’s specifications. We assessed cryptococcal antigenuria prevalence among participants with CD4 <200 cells/mm3, and stratified results by CD4 categories. Results Among 432 participants, mean age was 36.1 ±9.9 years and 172 (40%) were female. The overall estimated prevalence of cryptococcal antigenuria was 9.0% (95% CI 6.5–12.1%). CD4 counts were available for 319 (74%) participants; median CD4 was 75 cells/mm3 [Interquartile Range (IQR) 34–129 cells/mm3]. Participants with a negative cryptococcal antigenuria screening test had a median CD4 of 79 cells/mm3 (IQR 36-129 cells/mm3), while participants with a positive cryptococcal test had a median CD4 of 41 cells/mm3 (IQR 10-112 cells/mm3). The estimated prevalence of cryptococcal antigenuria among participants with CD4 <50 cells/mm3 was 12.5% (95% CI 7.0-20.1%), which was significantly higher than those with CD4 50-200 cells/mm3 (4.8%; 95% CI 2.3-8.7%). Conclusions Nearly 1 of 10 newly-diagnosed HIV-infected adults with CD4 <200 cells/mm3 in KwaZulu-Natal had evidence of cryptococcal antigenuria. Point-of-care CD4 count testing and cryptococcal antigen screening may rapidly identify cryptococcosis at the time of HIV diagnosis.

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