scholarly journals China NMPA perspective on clinical evaluation of SARS-CoV-2 antibody test reagents in the process of emergency approval

Bioanalysis ◽  
2020 ◽  
Author(s):  
Yunfeng Lv ◽  
Jingyun He ◽  
Rongzhi Liu ◽  
Yu Gao ◽  
Chao Xu ◽  
...  
Keyword(s):  
Early Stage ◽  
Antibody Test ◽  
Standard Test ◽  
Test Method ◽  
Antibody Detection ◽  
Test Results ◽  
Antibody Testing ◽  
National Medical ◽  
Key Points ◽  
Antigen Antibody

Coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The SARS-CoV-2 antibody testing an important supplement to nucleic acid testing. In the process of emergency approval, the Center for Medical Device Evaluation of the China National Medical Products Administration released The Key Points of Technical Review for the Registration of SARS-CoV-2 Antigen/Antibody Detection Reagents. The Clinical Study Requirement section of the Key Point has put forward requirements in terms of reference methods and subject enrolment among others, which can ensure that the test results can meet the clinical needs. This article draws on the experience of the China NMPA in evaluating diagnostic reagents used to supplement the gold standard test method in the early stage of an epidemic of an infectious disease, as well as to serve as reference for clinicians and regulators.

A Nationwide Survey of COVID-19 Testing in LGBTQ+ Populations in the United States

2021 ◽  
pp. 003335492110181
Author(s):  
Richard J. Martino ◽  
Kristen D. Krause ◽  
Marybec Griffin ◽  
Caleb LoSchiavo ◽  
Camilla Comer-Carruthers ◽  
...  
Keyword(s):  
United States ◽  
Gay Men ◽  
Antibody Test ◽  
Nationwide Survey ◽  
The United States ◽  
Sociodemographic Characteristics ◽  
Full Time ◽  
Test Results ◽  
Antibody Testing ◽  
And Gender

Objectives Lesbian, gay, bisexual, transgender, or queer and questioning (LGBTQ+) people and populations face myriad health disparities that are likely to be evident during the COVID-19 pandemic. The objectives of our study were to describe patterns of COVID-19 testing among LGBTQ+ people and to differentiate rates of COVID-19 testing and test results by sociodemographic characteristics. Methods Participants residing in the United States and US territories (N = 1090) aged ≥18 completed an internet-based survey from May through July 2020 that assessed COVID-19 testing and test results and sociodemographic characteristics, including sexual orientation and gender identity (SOGI). We analyzed data on receipt and results of polymerase chain reaction (PCR) and antibody testing for SARS-CoV-2 and symptoms of COVID-19 in relation to sociodemographic characteristics. Results Of the 1090 participants, 182 (16.7%) received a PCR test; of these, 16 (8.8%) had a positive test result. Of the 124 (11.4%) who received an antibody test, 45 (36.3%) had antibodies. Rates of PCR testing were higher among participants who were non–US-born (25.4%) versus US-born (16.3%) and employed full-time or part-time (18.5%) versus unemployed (10.8%). Antibody testing rates were higher among gay cisgender men (17.2%) versus other SOGI groups, non–US-born (25.4%) versus US-born participants, employed (12.6%) versus unemployed participants, and participants residing in the Northeast (20.0%) versus other regions. Among SOGI groups with sufficient cell sizes (n > 10), positive PCR results were highest among cisgender gay men (16.1%). Conclusions The differential patterns of testing and positivity, particularly among gay men in our sample, confirm the need to create COVID-19 public health messaging and programming that attend to the LGBTQ+ population.

scholarly journals Life span of Covid-19 antibodies following infection in a sample worker population in Qatar

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Mohamad Hamad BA Al-Naemi ◽  
Walid Sayed Hassanen ◽  
Sherif Fawzi Mohamed El Nahrawi ◽  
Rama Abdulsalam Rashad
Keyword(s):  
Social History ◽  
Antibody Test ◽  
Test Results ◽  
Antibody Testing ◽  
Study Population ◽  
Human Immune Response ◽  
Human Immune ◽  
Spread Of Infection ◽  
Test Result ◽  
Rule Out

Background: COVID-19 antibodies’ longevity following infection is still unclear. Early data brought hope that acquired immunity was possible but subsequent studies suggested that immune protection might be short-lived. The results of recent studies provide greater insight into the human immune response to COVID-19. The Qatar Gas medical department’s strategy in preventing spread of infection among offshore and onshore workers consisted of maximizing the opportunities for COVID-19 polymerise chain reaction (PCR) and antibody testing. A large amount of data revealing the possible lifespan of COVID-19 antibodies in the study population was collected. Methods: Out of hundreds of employees who volunteered in this study about seroprevalance of COVID-19 antibodies, 52 whose results were reactive were tested for COVID-19 PCR before being selected. Employees with reactive or inconclusive PCR test results were excluded. Age, medical/surgical/social history, apart from past COVID-19 infection, were not selection criteria. We measured the period of time between the date of diagnosis and the antibody test result, segregating those still reactive from those who tested non-reactive at any point in time. The reactive group were retested for antibodies every 90 days as long as results continued to be reactive. Any cured employee was retested if they developed symptoms or was exposed to a confirmed positive case, to rule out the possibility of re-infection during this timeframe. Results: Only one employee was non-reactive after 110 days of COVID-19 PCR positive test result. 22 employees tested reactive although their PCR result had been negative. 30 employees tested reactive after a positive PCR with an average duration of 145 days, the shortest and longest being 24 and 223 respectively. Conclusion: We determined that antibodies’ longevity may extend to more than 6 months following COVID-19 infection and that there may be an early decay of antibodies in a limited proportion of the population, however further studies are recommended on larger populations. We noticed no cases of COVID-19 reinfection.

scholarly journals Indicators of COVID-19 status in a cohort study of university staff and post-graduate research students, including results from home antibody testing

2020 ◽  
Author(s):  
Katrina A. S. Davis ◽  
Ewan Carr ◽  
Daniel Leightley ◽  
Valentina Vitiello ◽  
Gabriella Bergin-Cartwright ◽  
...  
Keyword(s):  
Cohort Studies ◽  
Antibody Test ◽  
Self Report ◽  
Test Results ◽  
Long Term Effects ◽  
Antibody Testing ◽  
Postgraduate Students ◽  
Research Students ◽  
Core Symptoms

AbstractBackgroundCohort studies of people with a history of COVID-19 infection and controls will be essential to understand the epidemiology of long-term effects. However, clinical diagnosis requires resources that are frequently restricted to the severely ill. Cohort studies may have to rely on surrogate indicators of COVID-19 illness. We describe the prevalence and overlap of five potential indicators: self-reported suspicion, self-reported core symptoms, symptom algorithm, self-reported routine test results, and home antibody testing.MethodsAn occupational cohort of staff and postgraduate students at a large London university who participated in surveys and antibody testing. Self-report items cover March to June 2020 and antibody test results from ‘lateral flow’ IgG/IgM antibody test cassettes sent to participants in June 2020.ResultsValid antibody test results were returned for 1882 participants. Of the COVID-19 indicators, the highest prevalence was core symptoms (770 participants positive, 41%), followed by participant suspicion of infection (n=509, 27%), a symptom algorithm (n=297, 16%), study antibody positive test (n=124, 6.6%) and self-report of a positive external test (n=39, 2.1%). Study antibody positive result was rare in people who had no suspicion they had experienced COVID-19 (n=4, 0.7%) or did not experience core symptoms (n=10, 1.6%). When study antibody test results were compared with earlier external antibody results in those who had reported them, the study antibody results agreed in 88% cases (kappa= 0.636), with a lower proportion testing positive on this occasion (proportion with antibodies detected 15% in study test vs 24% in external testing).DiscussionOur results demonstrate that there is some agreement between different COVID indicators, but that they a more complete story when used together. Antibody testing may provide greater certainty and be one of the only ways to detect asymptomatic cases, but is likely to under-ascertain due to weak antibody responses to mild infection, which wane over time. Cohort studies will need to review how they deal with different and sometimes conflicting indicators of COVID-19 illness in order to study the long-term outcomes of COVID-19 infection and related impacts.What is already known on this subject?Research into the effects of COVID-19 in the community is needed to respond to the pandemic. Objective testing has not been widely available and accuracy may not be high when carried out in retrospect. Many cohort studies are considering how best to measure COVID-19 infection status.What this study adds?Antibody testing is feasible, but it is possible that sensitivity may be poor. Each indicator included added different aspects to the ascertainment of COVID-19 exposure. Using combinations of self-reported and objectively measured variables, it may be possible to tailor COVID-19 indicators to the situation.

scholarly journals LB-12. SARS-CoV-2 RNA and Antibodies among People Experiencing Homelessness and Staying in Shelters or Outdoor Encampments in Denver, Colorado, May-July 2020

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S849-S850
Author(s):  
David McCormick ◽  
Tracy Scott ◽  
Jesse Chavez ◽  
Kay Wilcox ◽  
Grace E Marx ◽  
...  
Keyword(s):  
Native American ◽  
Venous Blood ◽  
Antibody Test ◽  
Sociodemographic Factors ◽  
Mitigation Strategies ◽  
Homeless Shelters ◽  
Test Results ◽  
Rt Pcr ◽  
Antibody Testing ◽  
Antibody Tests

Abstract Background The COVID-19 pandemic has disproportionately affected people experiencing homelessness (PEH) residing in shelters. Initial and regular testing of PEH in communities with moderate or substantial SARS-CoV-2 transmission may limit spread in shelters. We analyzed factors associated with positive SARS-CoV-2 RNA and antibody tests for PEH staying in shelters or encampments in Denver, Colorado. Methods In May 2020, Denver Public Health collaborated with local leaders to identify 4 homeless shelters and 3 outdoor encampments for voluntary, universal SARS-CoV-2 testing. At each testing event, a short questionnaire including sociodemographic factors and symptoms was administered to PEH who consented to testing. SARS-CoV-2 RNA testing by reverse transcription polymerase chain reaction (RT-PCR) was performed on nasopharyngeal swabs; antibody testing was performed on venous blood samples. PEH reporting a prior positive RT-PCR test were not retested but were eligible for antibody testing. Statistical calculations were performed with an α of 0.05; all tests were two-sided. Results From June 2–July 28, 2020, 931 PEH were approached. A total of 863 RT-PCR tests were performed at 14 testing events, and 334 antibody tests were performed at 5 testing events. Overall, 604 and 259 RT-PCR tests were conducted in 4 shelters and 3 encampments, respectively; 189 and 145 antibody tests were conducted in 3 shelters and 2 encampments, respectively. PEH tested in shelters were older, more often men, less often Native American, and less likely to report COVID-19 symptoms than those tested at encampments (Table 1). Overall, 9% of PEH tested in shelters tested positive for SARS-CoV-2 compared to 3% of PEH tested in encampments (p=0.002); 8% of men had positive RT-PCR results compared to 2% of women (p=0.03) (Table 2). PEH tested at shelters had a higher percentage of detectable SARS-CoV-2 antibodies than those tested in encampments (24% vs 8%, p=0.0002; Table 3). Neither RT-PCR nor antibody test results differed significantly by race or ethnicity. Table 1. Demographics of participants residing in encampments compared with shelters in Denver, Colorado, May-July 2020 (n=931) Table 2. Comparison of participants testing positive or negative for SARS-CoV-2 RT-PCR* by location and demographics, in Denver, Colorado, May-July 2020 Table 3. Comparison of participants testing positive or negative for antibodies against SARS-CoV-2 by location and demographics in Denver, Colorado, May-July 2020 Conclusion A greater percentage of PEH tested positive for both SARS-CoV-2 RNA and antibodies at shelters than encampments, suggesting that continued assessment of mitigation strategies in shelters should be a priority. Disclosures All Authors: No reported disclosures

scholarly journals Behavioural responses to SARS-CoV-2 antibody testing in England: REACT-2 study

2021 ◽  
Vol 6 ◽  
pp. 203
Author(s):  
Rozlyn Redd ◽  
Emily Cooper ◽  
Christina Atchison ◽  
Isabella Pereira ◽  
Polly Hollings ◽  
...  
Keyword(s):  
Research Programme ◽  
Antibody Test ◽  
Test Results ◽  
Antibody Testing ◽  
Community Based ◽  
Prevalence Studies ◽  
Behavioural Responses ◽  
Self Testing ◽  
Community Transmission

Background:  This study assesses the behavioural responses to SARS-CoV-2 antibody test results as part of the REal-time Assessment of Community Transmission-2 (REACT-2) research programme, a large community-based surveillance study of antibody prevalence in England. Methods: A follow-up survey was conducted six weeks after the SARS-CoV-2 antibody test. The follow-up survey included 4500 people with a positive result and 4039 with a negative result. Reported changes in behaviour were assessed using difference-in-differences models. A nested interview study was conducted with 40 people to explore how they thought through their behavioural decisions. Results: While respondents reduced their protective behaviours over the six weeks, we did not find evidence that positive test results changed participant behaviour trajectories in relation to the number of contacts the respondents had, for leaving the house to go to work, or for leaving the house to socialise in a personal place. The qualitative findings supported these results. Most people did not think that they had changed their behaviours because of their test results, however they did allude to some changes in their attitudes and perceptions around risk, susceptibility, and potential severity of symptoms. Conclusions: We found limited evidence that knowing your antibody status leads to behaviour change in the context of a research study. While this finding should not be generalised to widespread self-testing in other contexts, it is reassuring given the importance of large prevalence studies, and the practicalities of doing these at scale using self-testing with lateral flow immunoassay (LFIA).

Detection of Antiphospholipid Antibodies Using a Novel Multiplex Test Method: Correlation with ELISA Methods.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 4102-4102
Author(s):  
Kim A. Janatpour ◽  
Robert C. Gosselin ◽  
John T. Owings ◽  
Ted Wun
Keyword(s):  
Cost Effective ◽  
Elisa Test ◽  
Small Sample ◽  
Test Method ◽  
Antibody Detection ◽  
Antiphospholipid Antibody ◽  
Antiphospholipid Antibody Syndrome ◽  
Test Results ◽  
Clinical Sensitivity ◽  
Positive Results

Abstract -Background: Laboratory criteria for the antiphospholipid antibody syndrome (APS) include detection of the lupus anticoagulant (LA) by coagulation based tests, or detection of either anti-cardiolipin (aCL), or anti-B2-glycoprotein I (aB2GPI) antibodies by enzyme-linked immunoabsorbant assay (ELISA). Multiplex testing enables simultaneous measurement of multiple serum antibodies with small beads coated with target antigens and small sample volumes (5 μL). We compared the concordance of a prototype multiplex method to standard ELISA methods for measuring IgG and IgM antibodies directed against CL or B2GPI. Methods: Samples from patients with suspected APS were tested for IgG and IgM aCL and aB2GPI antibodies using standard ELISA methods (ELISA, Bio-Rad Laboratories, Hercules, CA) and by a prototype multiplex bead set analyzed on the BioPlex 2200 (Bio-Rad Laboratories, Hercules, CA). The multiplex method used beads coated with either CL alone, B2GPI alone, or CL-B2GPI complex. Results were normalized using ratios (obtained result/upper limit of normal). A positive result was defined as a ratio of > 1. For CL, the multiplex test is considered positive if positive results are present using beads with either the CL alone or the CL-B2GPI complex. Results: Table 1. Concordance of ELISA vs Multiplex tests for antiphospholipid antibody detection Multiplex Test Results Concordance (%) ELISA Test Results Positive Negative Positive Negative All Results aCL-IgG Positive (n=52) 30 22 58 - Negative (n=232) 32 200 - 86 82 aCL-IgM Positive (n=42) 32 10 76 - Negative (n=241) 34 207 - 85 84 aβ2GPI-IgG Positive (n=34) 20 14 59 - Negative (n=249) 17 232 - 93 89 aβ2GPI-IgM Positive (n=61) 31 30 51 - Negative (n=219) 22 197 - 90 81 Conclusions: The overall concordance of multiplex results with ELISA results was good (81–89%). Negative multiplex results showed excellent correlation with ELISA (85–93%). Positive multiplex results had variable correlation with ELISA (51–76%). Evaluation of clinically significant positive results and clinical outcome measures is needed to determine clinical sensitivity and specificity of the multiplex test. Further refinement of the multiplex platform may provide an efficient and cost-effective assay for antibodies associated with the antiphospholipid syndrome.

scholarly journals SARS-CoV-2 Serologic Assays in Control and Unknown Populations Demonstrate the Necessity of Virus Neutralization Testing.

2020 ◽  
Author(s):  
Jennifer A Rathe ◽  
Emily A Hemann ◽  
Julie Eggenberger ◽  
Zhaoqi Li ◽  
Megan Knoll ◽  
...  
Keyword(s):  
Antibody Test ◽  
Negative Control ◽  
Virus Neutralization ◽  
Antibody Detection ◽  
Immune Protection ◽  
Antibody Testing ◽  
Viral Neutralization ◽  
Positive Antibody ◽  
Antibody Assays ◽  
Focus Reduction

Background: To determine how serologic antibody testing outcome links with virus neutralization of SARS-CoV-2 to ascertain immune protection status, we evaluated a unique set of individuals for SARS-CoV-2 antibody detection and viral neutralization. Methods: Herein, we compare several analytic platforms with 15 positive and 30 negative SARS-CoV-2 infected controls followed by viral neutralization assessment. We then applied these platforms in a clinically relevant population: 114 individuals with unknown histories of SARS-CoV-2 infection. Results: In control populations, the best performing antibody detection assays were SARS-CoV-2 receptor binding domain (RBD) IgG (specificity 87%, sensitivity 100%, PPV 100%, NPV 93%), spike IgG3 (specificity 93%, sensitivity 97%, PPV 93%, NPV 97%), and nucleocapsid (NP) protein IgG (specificity 93%, sensitivity 97%, PPV 93%, NPV 97%). Neutralization of positive and negative control sera showed 100% agreement. 20 unknown individuals had detectable SARS-CoV-2 antibodies with 16 demonstrating virus neutralization. The antibody assays that best predicted virus neutralization were RBD IgG (misidentified 2), spike IgG3 (misidentified 1), and NP IgG (misidentified 2). Conclusion: These data suggest that meaningful evaluation of antibody assay performance requires testing in an unknown population. Further, these results indicate coupling of virus neutralization analysis to a positive antibody test is required to categorize patients based on SARS-CoV-2 immune protection status following virus exposure or vaccine administration. One of the antibody detection platforms identified in this study followed by the pseudoneutralization or focus reduction assay would provide a practical testing strategy to assess for SARS-CoV-2 antibodies with optimal prediction of correlates to neutralizing immunity.

scholarly journals SARS-CoV-2 Serologic Assays in Control and Unknown Populations Demonstrate the Necessity of Virus Neutralization Testing

2020 ◽  
Author(s):  
Jennifer A Rathe ◽  
Emily A Hemann ◽  
Julie Eggenberger ◽  
Zhaoqi Li ◽  
Megan L Knoll ◽  
...  
Keyword(s):  
Predictive Value ◽  
Nucleocapsid Protein ◽  
Antibody Test ◽  
Negative Control ◽  
Virus Neutralization ◽  
Antibody Detection ◽  
Antibody Testing ◽  
Neutralization Activity ◽  
Viral Neutralization ◽  
Virus Specific Antibody

Abstract Background To determine how serologic antibody testing outcome links with virus neutralization of SARS-CoV-2, we evaluated a unique set of individuals for SARS-CoV-2 antibody level and viral neutralization. Methods We compared serum Ig levels across platforms of viral antigens and antibodies with 15 positive and 30 negative SARS-CoV-2 controls followed by viral neutralization assessment. We then applied these platforms to a clinically relevant cohort of 114 individuals with unknown histories of SARS-CoV-2 infection. Results In controls, the best performing virus-specific antibody detection platforms were SARS-CoV-2 receptor binding domain (RBD) IgG [specificity 87%, sensitivity 100%, positive predictive value (PPV) 100%, negative predictive value (NPV) 93%], spike IgG3 [specificity 93%, sensitivity 97%, PPV 93%, NPV 97%], and nucleocapsid protein (NP) IgG [specificity 93%, sensitivity 97%, PPV 93%, NPV 97%]. Neutralization of positive and negative control sera showed 100% agreement. 20 unknown individuals had detectable SARS-CoV-2 antibodies with 16 demonstrating virus neutralization. Spike IgG3 provided the highest accuracy for predicting serologically positive individuals with virus neutralization activity [Misidentified 1/20 unknowns compared to 2/20 for RBD and NP IgG]. Conclusion The coupling of virus neutralization analysis to a spike IgG3 antibody test is optimal to categorize patients for correlates of SARS-CoV-2 immune protection status.

scholarly journals Clinically based score predicting cryptogenic NORSE at the early stage of status epilepticus

2020 ◽  
Vol 7 (5) ◽  
pp. e849
Author(s):  
Atsuko Yanagida ◽  
Naomi Kanazawa ◽  
Juntaro Kaneko ◽  
Atsushi Kaneko ◽  
Ryoko Iwase ◽  
...  
Keyword(s):  
Status Epilepticus ◽  
Early Stage ◽  
Brain Mri ◽  
Ventilatory Support ◽  
Antibody Test ◽  
Refractory Status Epilepticus ◽  
Test Results ◽  
Tumor Association ◽  
Unclear Etiology ◽  
Score Range

ObjectiveTo determine whether a clinically based score predicts cryptogenic new-onset refractory status epilepticus (C-NORSE) at the early stage of status epilepticus (SE) with prominent motor symptoms (SE-M) of unclear etiology.MethodsThe score (range 0–6) included 6 clinical features: highly refractoriness to antiseizure drugs, previously healthy individual, presence of prodromal fever, absence of prodromal psychobehavioral or memory alterations, absence of dyskinesias, and symmetric brain MRI abnormalities (the first 2 mandatory). We retrospectively assessed the usefulness of a high scale score (≥5) in predicting C-NORSE in 83 patients with SE-M of unclear etiology, who underwent testing for neuronal surface antibodies (NS-Abs) between January 2007, and December 2019.ResultsThirty-one (37.3%) patients had a high score. Patients with a high score had more frequent prodromal fever (28/31 vs 24/52), mechanical ventilatory support (31/31 vs 36/52), and symmetric MRI abnormalities (26/31 vs 12/52), had less frequent involuntary movements (2/31 vs 30/52), and had absent prodromal psychobehavioral alterations (0/31 vs 27/52), CSF oligoclonal band detection (0/27 vs 11/38), tumor association (0/31 vs 13/52), or NS-Abs (0/31 vs 29/52) than those with a low score (<5). Thirty-three patients (median age, 27 years; 18 [54.5%] female) were finally regarded as C-NORSE. The sensitivity and specificity of a high score for predicting C-NORSE were 93.9% (95% CI 0.87–0.94) and 100% (95% CI 0.95–1.00), respectively.ConclusionsPatients with a high score in the indicated scale are more likely to have C-NORSE, making it a useful diagnostic tool at the early stage of SE-M before antibody test results become available.

scholarly journals Behavioural responses to SARS-CoV-2 antibody testing in England: REACT-2 study

2021 ◽  
Vol 6 ◽  
pp. 203
Author(s):  
Rozlyn Redd ◽  
Emily Cooper ◽  
Christina Atchison ◽  
Isabella Pereira ◽  
Polly Hollings ◽  
...  
Keyword(s):  
Research Programme ◽  
Antibody Test ◽  
Test Results ◽  
Antibody Testing ◽  
Community Based ◽  
Prevalence Studies ◽  
Behavioural Responses ◽  
Self Testing ◽  
Community Transmission

Background:  This study assesses the behavioural responses to SARS-CoV-2 antibody test results as part of the REal-time Assessment of Community Transmission-2 (REACT-2) research programme, a large community-based surveillance study of antibody prevalence in England. Methods: A follow-up survey was conducted six weeks after the SARS-CoV-2 antibody test. The follow-up survey included 4500 people with a positive result and 4039 with a negative result. Reported changes in behaviour were assessed using difference-in-differences models. A nested interview study was conducted with 40 people to explore how they thought through their behavioural decisions. Results: While respondents reduced their protective behaviours over the six weeks, we did not find evidence that positive test results changed participant behaviour trajectories in relation to the number of contacts the respondents had, for leaving the house to go to work, or for leaving the house to socialise in a personal place. The qualitative findings supported these results. Most people did not think that they had changed their behaviours because of their test results, however they did allude to some changes in their attitudes and perceptions around risk, susceptibility, and potential severity of symptoms. Conclusions: We found limited evidence that knowing your antibody status leads to behaviour change in the context of a research study. While this finding should not be generalised to widespread self-testing in other contexts, it is reassuring given the importance of large prevalence studies, and the practicalities of doing these at scale using self-testing with lateral flow immunoassay (LFIA).

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