Combined point of care SARS-CoV-2 nucleic acid and antibody testing in suspected moderate to severe COVID-19 disease

Abstract

Background Rapid COVID-19 diagnosis in hospital is essential for patient management and identification of infectious patients to limit the potential for nosocomial transmission. The diagnosis of infection is complicated by 30-50% of COVID-19 hospital admissions with nose/throat swabs testing negative for SARS-CoV-2 nucleic acid, frequently after the first week of illness when SARS-CoV-2 antibody responses become detectable. We assessed the diagnostic accuracy of combined rapid antibody point of care (POC) and nucleic acid assays for suspected COVID-19 disease in the emergency department. Methods We developed (i) an in vitro neutralization assay using a lentivirus expressing a genome encoding luciferase and pseudotyped with spike (S) protein and (ii) an ELISA test to detect IgG antibodies to nucleocapsid (N) and S proteins from SARS-CoV-2. We tested two lateral flow rapid fingerprick tests with bands for IgG and IgM. We then prospectively recruited participants with suspected moderate to severe COVID-19 and tested for SARS-CoV-2 nucleic acid in a combined nasal/throat swab using the standard laboratory RT-PCR and a validated rapid POC nucleic acid amplification (NAAT) test. Additionally, serum collected at admission was retrospectively tested by in vitro neutralisation, ELISA and the candidate POC antibody tests. We evaluated the performance of the individual and combined rapid POC diagnostic tests against a composite reference standard of neutralisation and standard laboratory based RT-PCR. Results 45 participants had specimens tested for nucleic acid in nose/throat swabs as well as stored sera for antibodies. Using the composite reference standard, prevalence of COVID-19 disease was 53.3% (24/45). Median age was 73.5 (IQR 54.0-86.5) years in those with COVID-19 disease by our reference standard and 63.0 (IQR 41.0-72.0) years in those without disease. The overall detection rate by rapid NAAT was 79.2% (95CI 57.8-92.9%), decreasing from 100% (95% CI 65.3-98.6%) in days 1-4 to 50.0% (95% CI 11.8-88.2) for days 9-28 post symptom onset. Correct identification of COVID-19 with combined rapid POC diagnostic tests was 100% (95CI 85.8-100%) with a false positive rate of 5.3-14.3%, driven by POC LFA antibody tests. Conclusions Combined POC tests have the potential to transform our management of COVID-19, including inflammatory manifestations later in disease where nucleic acid test results are negative. A rapid combined approach will also aid recruitment into clinical trials and in prescribing therapeutics, particularly where potentially harmful immune modulators (including steroids) are used.

Performance Evaluation of the SAMBA II SARS-CoV-2 Test for Point-of-Care Detection of SARS-CoV-2

“…POC molecular tests for SARS-CoV-2, such as SAMBA II, are required to quickly triage patients as centralised testing can take 2-5 days for results [20,21]. In addition, POC tests would be extremely useful for non-laboratory residential settings such as prisons, immigration centres, nursing homes and rehabilitative centres.…”

Clinical utility of targeted SARS-CoV-2 serology testing to aid the diagnosis and management of suspected missed, late or post-COVID-19 infection syndromes: results from a pilot service

“…The main limitation of this study is in being performed at a single-centre at a discrete time-point in the COVID-19 pandemic. It is impossible to predict precise future serology service needs, whether that be aiding acute diagnosis alongside PCR testing, (23) informing patients that they have or have not had COVID-19, helping guide infection control decisions in hospitals or helping diagnose emerging post-inflammatory syndromes. Faster, more accurate even point of care SARS-CoV-2 virus detection assays may become widely available in hospitals and the community during a second wave, reducing the number of missed or delayed diagnoses and thus reduce demand for serological testing.…”

Nanotechnology and COVID-19: Prevention, diagnosis, vaccine, and treatment strategies

“…Lateral flow tests (LFTs) (Cui and Zhou, 2020;Rosati et al, 2021), which are paper-based devices, are able to meet the needs wait of a biosensor (specific identification of target analyte, low cost, stability, user-friendly test format, fast, and low sample volume) (Ozturk et al, 2021). In addition, proteins, nucleic acids, and whole cells are biomarkers of LFTs, and they serve as POC testing (Mlcochova et al, 2020). This can provide support for patients and personalized medicine.…”