ABSTRACT
BACKGROUND: Antigen lateral flow devices (LFDs) have been widely used to control SARS-CoV-2. We aimed to improve understanding of LFD performance with changes in variant infections, vaccination, viral load, and LFD use, and in the detection of infectious individuals. METHODS: In this diagnostic study, paired LFD and RT-PCR test results were prospectively collected from asymptomatic and symptomatic participants in the UK between Nov 4, 2020, and March 21, 2022, to support the National Health Service (NHS) England's Test and Trace programme. The LFDs evaluated were the Innova SARS-CoV-2 Antigen Rapid Qualitative Test, the Orient Gene Rapid Covid-19 (Antigen) Self-Test, and the Acon Flowflex SARS-CoV-2 Antigen Rapid Test (Self-Testing). Test results were collected across various community testing settings, including predeployment testing sites, routine testing centres, homes, schools, universities, workplaces, targeted community testing, and from health-care workers. We used multivariable logistic regression to analyse LFD sensitivity and specificity using RT-PCR as a reference standard, adjusting for viral load, LFD manufacturer, test setting, age, sex, test assistance, symptom status, vaccination status, and SARS-CoV-2 variant. National contact tracing data from NHS Test and Trace (Jan 1, 2021, to Jan 11, 2022) were used to estimate the proportion of transmitting index patients (with ≥1 RT-PCR-positive or LFD-positive contact) potentially detectable by LFDs (specifically Innova, as the most widely used LFD) with time, accounting for index viral load, variant, and symptom status. FINDINGS: We assessed 75 382 pairs of LFD and RT-PCR tests. Of these, 4131 (5·5%) were RT-PCR-positive. LFD sensitivity versus RT-PCR was 63·2% (95% CI 61·7-64·6) and specificity was 99·71% (95% CI 99·66-99·74). Increased viral load was independently associated with being LFD positive (adjusted odds ratio [aOR] 2·85 [95% CI 2·66-3·06] per 1 log10 copies per mL increase; p<0·0001). There was no evidence that LFD sensitivity differed for delta (B.1.617.2) infections versus alpha (B.1.1.7) or pre-alpha (B.1.177) infections (aOR 1·00 [0·69-1·45]; p=0·99), whereas omicron (BA.1 or BA.2) infections appeared more likely to be LFD positive (aOR 1·63 [1·02-2·59]; p=0·042). Sensitivity was higher in symptomatic participants (68·7% [95% CI 66·9-70·4]) than in asymptomatic participants (52·8% [50·1-55·4]). Among 347 374 unique index patients with probable onward transmission, 78·3% (95% CI 75·3-81·2) were estimated to have been detectable with LFDs (Innova), and this proportion was mostly stable with time and for successive variants. Overall, the estimated proportion of infectious index patients detectable by the Innova LFD was lower in asymptomatic patients (57·6% [53·6-61·9]) versus symptomatic patients (79·7% [76·7-82·5]). INTERPRETATION: LFDs remained able to detect most SARS-CoV-2 infections throughout vaccine roll-out and across different viral variants. LFDs can potentially detect most infections that transmit to others and reduce the risk of transmission. However, performance is lower in asymptomatic individuals than in symptomatic individuals. FUNDING: UK Health Security Agency, the UK Government Department of Health and Social Care, National Institute for Health Research (NIHR) Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, and the University of Oxford NIHR Biomedical Research Centre.
ABSTRACT
BACKGROUND: Transmission of hepatitis E virus (HEV) within the healthcare setting is extremely rare. Additionally, the development of chronic HEV infection in association with severe acute respiratory syndrome coronavirus disease 2 (SARS-CoV-2) infection and/or its immunomodulatory therapy has not been reported previously. AIMS: To describe the investigation and management of a nosocomial HEV transmission incident during the coronavirus disease 2019 (COVID-19) pandemic. METHODS: Epidemiological and molecular investigation of two individuals hospitalised with COVID-19 who were both diagnosed with HEV infection. RESULTS: Findings from our investigation were consistent with transmission of HEV from one patient with a community-acquired HEV infection to another individual (identical HEV sequences were identified in the two patients), most likely due to a breach in infection control practices whilst both patients shared a bed space on the intensive care unit (ICU). Chronic HEV infection requiring treatment with ribavirin developed in one patient with prolonged lymphopaenia attributable to COVID-19 and/or the immunomodulators received for its treatment. Further investigation did not identify transmission of HEV to any other patients or to healthcare workers. CONCLUSIONS: The extraordinary demands that the COVID-19 pandemic has placed on all aspects of healthcare, particularly within ICU settings, has greatly challenged the ability to consistently maintain optimal infection prevention and control practices. Under the significant pressures of the COVID-19 pandemic a highly unusual nosocomial HEV transmission incident occurred complicated further by progression to a chronic HEV infection in one patient.