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1.
Front Med (Lausanne) ; 9: 859115, 2022.
Article in English | MEDLINE | ID: covidwho-1809423

ABSTRACT

Human T lymphotropic virus 1 (HTLV-1) is a public health issue for most countries and imposes important consequences on patients' health and socioeconomic status. Brazil is one of the global leaders of the public health response to these viruses. The country has challenges to overcome to implement meaningful policies aiming to eliminate HTLV-1/2. An analysis of strengths, weaknesses, opportunities, and threats (SWOT) for the implementation of public health policies on HTLV-1/2 was performed. The strengths identified were the Brazilian Unified Health System (SUS); Brazilian expertise in public health programs successfully implemented; currently available policies targeting HTLV; and strong collaboration with researchers and patient's representative. Lack of awareness about HTLV, insufficient epidemiological data, lack of reference centers for patient care, insufficient availability of confirmatory tests, lack of universal antenatal screening, and absence of cost-effectiveness studies were identified as weaknesses. Some interesting opportunities included the increased interest from international organizations on HTLV, possibility of integrating HTLV into other programs, external funding for research, available online platforms, opportunity to acquire data from HTLV-1/2 surveillance to gather epidemiological information, and HTLV policies that were implemented independently by states and municipalities. In addition to the COVID-19 pandemic, existing demands from different diseases, the country's demography and its marked sociocultural diversity and the volatility of the technical team working with HTLV-1/2 at the Brazilian Ministry of Health are threats to the implementation of public policies on HTLV-1/2. This SWOT analysis will facilitate strategic planning to allow continuous progress of the Brazilian response to HTLV-1/2 infection.

2.
J Virol Methods ; 302: 114475, 2022 04.
Article in English | MEDLINE | ID: covidwho-1652648

ABSTRACT

Accurate and sensitive detection of antibody to SARS-CoV-2 remains an essential component of the pandemic response. Measuring antibody that predicts neutralising activity and the vaccine response is an absolute requirement for laboratory-based confirmatory and reference activity. The viral receptor binding domain (RBD) constitutes the prime target antigen for neutralising antibody. A double antigen binding assay (DABA), providing the most sensitive format has been exploited in a novel hybrid manner employing a solid-phase S1 preferentially presenting RBD, coupled with a labelled RBD conjugate, used in a two-step sequential assay for detection and measurement of antibody to RBD (anti-RBD). This class and species neutral assay showed a specificity of 100 % on 825 pre COVID-19 samples and a potential sensitivity of 99.6 % on 276 recovery samples, predicting quantitatively the presence of neutralising antibody determined by pseudo-type neutralization and by plaque reduction. Anti-RBD is also measurable in ferrets immunised with ChadOx1 nCoV-19 vaccine and in humans immunised with both AstraZeneca and Pfizer vaccines. This assay detects anti-RBD at presentation with illness, demonstrates its elevation with disease severity, its sequel to asymptomatic infection and its persistence after the loss of antibody to the nucleoprotein (anti-NP). It also provides serological confirmation of prior infection and offers a secure measure for seroprevalence and studies of vaccine immunisation in human and animal populations. The hybrid DABA also displays the attributes necessary for the detection and quantification of anti-RBD to be used in clinical practice. An absence of detectable anti-RBD by this assay predicates the need for passive immune prophylaxis in at-risk patients.


Subject(s)
Antibodies, Viral/isolation & purification , COVID-19 , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/immunology , Animals , Antibodies, Neutralizing/isolation & purification , COVID-19/diagnosis , Ferrets , Humans , RNA, Viral , Seroepidemiologic Studies
3.
Sci Rep ; 12(1): 1885, 2022 02 03.
Article in English | MEDLINE | ID: covidwho-1671623

ABSTRACT

At-home sampling is key to large scale seroprevalence studies. Dried blood spot (DBS) self-sampling removes the need for medical personnel for specimen collection but facilitates specimen referral to an appropriately accredited laboratory for accurate sample analysis. To establish a highly sensitive and specific antibody assay that would facilitate self-sampling for prevalence and vaccine-response studies. Paired sera and DBS eluates collected from 439 sero-positive, 382 sero-negative individuals and DBS from 34 vaccine recipients were assayed by capture ELISAs for IgG and IgM antibody to SARS-CoV-2. IgG and IgM combined on DBS eluates achieved a diagnostic sensitivity of 97.9% (95%CI 96.6 to 99.3) and a specificity of 99.2% (95% CI 98.4 to 100) compared to serum, displaying limits of detection equivalent to 23 and 10 WHO IU/ml, respectively. A strong correlation (r = 0.81) was observed between serum and DBS reactivities. Reactivity remained stable with samples deliberately rendered inadequate, (p = 0.234) and when samples were accidentally damaged or 'invalid'. All vaccine recipients were sero-positive. This assay provides a secure method for self-sampling by DBS with a sensitivity comparable to serum. The feasibility of DBS testing in sero-prevalence studies and in monitoring post-vaccine responses was confirmed, offering a robust and reliable tool for serological monitoring at a population level.


Subject(s)
Antibodies, Viral/blood , COVID-19 Testing/methods , COVID-19/diagnosis , COVID-19/epidemiology , Dried Blood Spot Testing/methods , Immunoglobulin G/blood , Immunoglobulin M/blood , SARS-CoV-2/immunology , Specimen Handling/methods , Biomarkers/blood , COVID-19/immunology , COVID-19/virology , COVID-19 Vaccines/immunology , Feasibility Studies , Female , Humans , Male , Sensitivity and Specificity , Seroepidemiologic Studies
5.
Nat Commun ; 13(1): 80, 2022 01 10.
Article in English | MEDLINE | ID: covidwho-1616982

ABSTRACT

Cross-reactive immune responses to SARS-CoV-2 have been observed in pre-pandemic cohorts and proposed to contribute to host protection. Here we assess 52 COVID-19 household contacts to capture immune responses at the earliest timepoints after SARS-CoV-2 exposure. Using a dual cytokine FLISpot assay on peripheral blood mononuclear cells, we enumerate the frequency of T cells specific for spike, nucleocapsid, membrane, envelope and ORF1 SARS-CoV-2 epitopes that cross-react with human endemic coronaviruses. We observe higher frequencies of cross-reactive (p = 0.0139), and nucleocapsid-specific (p = 0.0355) IL-2-secreting memory T cells in contacts who remained PCR-negative despite exposure (n = 26), when compared with those who convert to PCR-positive (n = 26); no significant difference in the frequency of responses to spike is observed, hinting at a limited protective function of spike-cross-reactive T cells. Our results are thus consistent with pre-existing non-spike cross-reactive memory T cells protecting SARS-CoV-2-naïve contacts from infection, thereby supporting the inclusion of non-spike antigens in second-generation vaccines.


Subject(s)
Antibodies, Viral/immunology , COVID-19/immunology , Contact Tracing/methods , Cross Reactions/immunology , SARS-CoV-2/immunology , Adult , COVID-19/epidemiology , COVID-19/virology , Coronavirus/immunology , Coronavirus/physiology , Epitopes, T-Lymphocyte/immunology , Female , Humans , Male , /virology , Middle Aged , Pandemics/prevention & control , SARS-CoV-2/genetics , SARS-CoV-2/physiology , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology , Spike Glycoprotein, Coronavirus/metabolism , Viral Proteins/genetics , Viral Proteins/immunology , Viral Proteins/metabolism , Young Adult
6.
2021.
Preprint in English | Other preprints | ID: ppcovidwho-294516

ABSTRACT

Background Assessing transmission of SARS-CoV-2 by children in schools is of critical importance in informing public health action. Quantification of transmission by active contact tracing in children and their contacts can be practically challenging even in non-pandemic times. Methods Cases of COVID-19 in children in London schools were identified through statutory notification and matched to schools reporting cases. Bubble and non-bubble ‘control’ contacts at school and household contacts for each case were longitudinally sampled and tested for SARS-CoV2 using PCR. Surfaces and air in the home and school environment were also subject to longitudinal sampling and testing for SARS-CoV-2 for 21 days or 28 days. Results Secondary transmission was not detected in 28 individual Bubble contacts, representing 10 distinct bubbles. Across the 8 non-bubble ‘school contact’ classes, 3/62 pupils tested positive – all three were asymptomatic and tested positive in one setting on the same day, unrelated to the original index case. In contrast the secondary attack rate in naïve household contacts of children was 14.5% and the inferred secondary attack rate was 25%. Environmental contamination with SARS-CoV-2 was rare in all schools studied, regardless of school type. This contrasted with contamination in households, where 20-30% of samples were positive. Summary The low levels of environmental contamination in schools are consistent with low transmission frequency and adequate levels of cleaning and ventilation in schools during the period of study. Secondary transmission in schools appeared to be infrequent during the study period. The frequency of secondary transmission in households associated with evident viral shedding throughout the home points to a need to improve advice to households with diagnosed infection in children.

7.
Sci Adv ; 7(22)2021 05.
Article in English | MEDLINE | ID: covidwho-1388434

ABSTRACT

The coronaviral spike is the dominant viral antigen and the target of neutralizing antibodies. We show that SARS-CoV-2 spike binds biliverdin and bilirubin, the tetrapyrrole products of heme metabolism, with nanomolar affinity. Using cryo-electron microscopy and x-ray crystallography, we mapped the tetrapyrrole interaction pocket to a deep cleft on the spike N-terminal domain (NTD). At physiological concentrations, biliverdin significantly dampened the reactivity of SARS-CoV-2 spike with immune sera and inhibited a subset of neutralizing antibodies. Access to the tetrapyrrole-sensitive epitope is gated by a flexible loop on the distal face of the NTD. Accompanied by profound conformational changes in the NTD, antibody binding requires relocation of the gating loop, which folds into the cleft vacated by the metabolite. Our results indicate that SARS-CoV-2 spike NTD harbors a dominant epitope, access to which can be controlled by an allosteric mechanism that is regulated through recruitment of a metabolite.


Subject(s)
COVID-19/immunology , Heme/metabolism , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/immunology , Spike Glycoprotein, Coronavirus/metabolism , Antibodies, Monoclonal/immunology , Antibodies, Monoclonal/metabolism , Antibodies, Neutralizing/immunology , Bilirubin/metabolism , Biliverdine/metabolism , Cryoelectron Microscopy , Crystallography, X-Ray , Epitopes , Humans , Immune Sera , SARS-CoV-2/immunology , SARS-CoV-2/pathogenicity
8.
Blood ; 136(Supplement 1):20-20, 2020.
Article in English | PMC | ID: covidwho-1339076

ABSTRACT

Background:The new SARS-CoV-2-induced disease (COVID-19) pandemic has represented a huge challenge for the health systems and has been responsible for almost 700.000 deaths worldwide as of 1st August 2020. Older age, male sex, comorbidities, ethnicity and socioeconomic factorsare risk factors for severe COVID-19. While the direct effect of solid cancer on the COVID-19 outcome has been investigated and is still debated, limited information is available on the impact of an underlying hematological malignancy on the risk of contracting SARS-CoV-2, the clinical presentation and the outcome of the infection.We report on the prevalence of SARS-CoV-2 infection in a large cohort of patients (pts) with chronic myeloid leukemia (CML).Methods:We retrospectively investigated the exposure to SARS-CoV-2 through serological testing in a single centre cohort of CML pts. Of more than 600 pts on active follow-up, we have screened 161 pts between 1st June and 27th July 2020. At each consultation, we recorded any exposure to or symptoms of SARS-CoV-2 infection in the preceding 6 months.The Imperial Hybrid DABA, a two-step double antigen binding assay (DABA) for the detection and measurement of total antibody directed to the receptor binding domain (RBD) of SARS-CoV-2 was used for analysis. The cut-off (CO) for positivity is established by adding 0.1 to the average of optical density (OD) obtained for the negative controls. A sample-OD/cut-off (S/CO) value ≥ 1 is considered reactive.Results:161 CML pts in chronic phase underwent serological testing (median age 54 years (18-92), male n=94). Twenty pts were off TKI (post-alloSCT, n=12;in treatment free remission n=6;pregnancy=1 and intolerance n=1) and 141 were on active treatment (imatinib [n=41], dasatinib [n=38], nilotinib [n=23], bosutinib [n=21], asciminib [n=11], ponatinib [n=6] and K0706 [n=1]). The ethnic distribution was White (n=119), Asian-Indian (n= 24), Asian-Chinese (n=3), Black (n=9), Arab (n=5), Mixed Asian-White (n=1).Eighteen pts (11.2%) have tested positive (Table 1). Thirty-eight pts (23.6%) reported symptoms compatible with COVID-19 of whom 12 (31.6%) were DABA positive. Six of 123 (4.9%) asymptomatic pts also tested positive. The time from onset of symptoms to the date of testing were similar in both seropositive (105 days, range 56-180) and seronegative pts (100 days, range 21-205). The median S/CO ratio was 9.9 (1-23.3) in the symptomatic and 1.5 (1.2-21.4) in the asymptomatic pts.Among the 18 positive pts, the median age at symptom presentation was 54 years (38-75) and 12 were males. The median time from CML diagnosis was 7.6 years (0.2-20) and two pts were post-alloSCT. Ethnicity was White, Asian-Indian, Black in 8 (44.4%), 6 (33%) and 4 (22.2%), respectively.In 15 pts (83.3%) symptoms were absent or mild, moderate in 2 and severe in one patient 2 years post-alloSCT on continuing immunosuppression for GvHD. Only 2/18 had PCR tests for SARS-CoV-2 at the time of infection and both were positive. Of the 16 pts not tested for antigen, 2 had been in close contact with a family member with a PCR-confirmed SARS-CoV-2 infection. In the mild cases, the most frequent symptoms were fever (n=7) and cough (n=6), followed by fatigue (n=2), myalgia (n=2) and anosmia (n=2). One patient presented only with acute limb ischemia, derived from thrombus in the superficial femoral artery. One patient had radiological features of COVID-19 pneumonia, but did not require hospitalization. The only patient with severe COVID-19 developed pneumonia requiring CPAP, was refractory to tocilizumab (anti-IL6), but recovered after starting ruxolitinib (JAK2-inhibitor). The median time to complete resolution of symptoms was 21 days (7-56).Conclusions:The prevalence of infection in our CML pts is similar to that of the overall population, which suggests that they are capable of mounting appropriate antibody response against SARS-CoV-2.Importantly, in seropositive pts symptoms were mild. Of note is the higher prevalence in the BAME community and underlines the potential role of socioeconomic fact rs in disease transmission. Expansion of this CML cohort and serial antibody testing in seropositive patients will provide further information regarding prevalence and durability of serological responses.

10.
J Infect Dis ; 223(10): 1671-1676, 2021 05 28.
Article in English | MEDLINE | ID: covidwho-1120054

ABSTRACT

It is currently unknown how post-COVID-19 syndrome (PCS) may affect those infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This longitudinal study includes healthcare staff who tested positive for SARS-CoV-2 between March and April 2020, with follow-up of their antibody titers and symptoms. More than half (21 of 38) had PCS after 7-8 months. There was no statistically significant difference between initial reverse-transcription polymerase chain reaction titers or serial antibody levels between those who did and those who did not develop PCS. This study highlights the relative commonality of PCS in healthcare workers and this should be considered in vaccination scheduling and workforce planning to allow adequate frontline staffing numbers.


Subject(s)
Antibodies, Viral/biosynthesis , COVID-19/complications , Health Personnel , SARS-CoV-2/immunology , Adult , Aged , Anosmia , COVID-19/immunology , Cohort Studies , Fatigue , Female , Headache , Humans , Longitudinal Studies , Male , Middle Aged , Nasopharynx/virology , Respiratory Tract Diseases , Surveys and Questionnaires , Syndrome , United Kingdom , Young Adult
11.
BMJ ; 372: n423, 2021 03 02.
Article in English | MEDLINE | ID: covidwho-1115122

ABSTRACT

OBJECTIVE: To evaluate the performance of new lateral flow immunoassays (LFIAs) suitable for use in a national coronavirus disease 2019 (covid-19) seroprevalence programme (real time assessment of community transmission 2-React 2). DESIGN: Diagnostic accuracy study. SETTING: Laboratory analyses were performed in the United Kingdom at Imperial College, London and university facilities in London. Research clinics for finger prick sampling were run in two affiliated NHS trusts. PARTICIPANTS: Sensitivity analyses were performed on sera stored from 320 previous participants in the React 2 programme with confirmed previous severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Specificity analyses were performed on 1000 prepandemic serum samples. 100 new participants with confirmed previous SARS-CoV-2 infection attended study clinics for finger prick testing. INTERVENTIONS: Laboratory sensitivity and specificity analyses were performed for seven LFIAs on a minimum of 200 serum samples from participants with confirmed SARS-CoV-2 infection and 500 prepandemic serum samples, respectively. Three LFIAs were found to have a laboratory sensitivity superior to the finger prick sensitivity of the LFIA currently used in React 2 seroprevalence studies (84%). These LFIAs were then further evaluated through finger prick testing on participants with confirmed previous SARS-CoV-2 infection: two LFIAs (Surescreen, Panbio) were evaluated in clinics in June-July 2020 and the third LFIA (AbC-19) in September 2020. A spike protein enzyme linked immunoassay and hybrid double antigen binding assay were used as laboratory reference standards. MAIN OUTCOME MEASURES: The accuracy of LFIAs in detecting immunoglobulin G (IgG) antibodies to SARS-CoV-2 compared with two reference standards. RESULTS: The sensitivity and specificity of seven new LFIAs that were analysed using sera varied from 69% to 100%, and from 98.6% to 100%, respectively (compared with the two reference standards). Sensitivity on finger prick testing was 77% (95% confidence interval 61.4% to 88.2%) for Panbio, 86% (72.7% to 94.8%) for Surescreen, and 69% (53.8% to 81.3%) for AbC-19 compared with the reference standards. Sensitivity for sera from matched clinical samples performed on AbC-19 was significantly higher with serum than finger prick at 92% (80.0% to 97.7%, P=0.01). Antibody titres varied considerably among cohorts. The numbers of positive samples identified by finger prick in the lowest antibody titre quarter varied among LFIAs. CONCLUSIONS: One new LFIA was identified with clinical performance suitable for potential inclusion in seroprevalence studies. However, none of the LFIAs tested had clearly superior performance to the LFIA currently used in React 2 seroprevalence surveys, and none showed sufficient sensitivity and specificity to be considered for routine clinical use.


Subject(s)
COVID-19 Serological Testing , COVID-19/diagnosis , Immunoassay , SARS-CoV-2/isolation & purification , Adult , Antibodies, Viral/blood , COVID-19/blood , COVID-19/epidemiology , Female , Humans , Male , Middle Aged , SARS-CoV-2/immunology , Sensitivity and Specificity , Seroepidemiologic Studies , United Kingdom
12.
J Infect Dis ; 223(2): 192-196, 2021 02 03.
Article in English | MEDLINE | ID: covidwho-1060994

ABSTRACT

At the start of the UK coronavirus disease 2019 epidemic, this rare point prevalence study revealed that one-third of patients (15 of 45) in a London inpatient rehabilitation unit were found to be infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) but asymptomatic. We report on 8 patients in detail, including their clinical stability, the evolution of their nasopharyngeal viral reverse-transcription polymerase chain reaction (RT-PCR) burden, and their antibody levels over time, revealing the infection dynamics by RT-PCR and serology during the acute phase. Notably, a novel serological test for antibodies against the receptor binding domain of SARS-CoV-2 showed that 100% of our asymptomatic cohort remained seropositive 3-6 weeks after diagnosis.


Subject(s)
COVID-19/diagnosis , COVID-19/immunology , Nasopharynx/virology , Rehabilitation Centers/statistics & numerical data , SARS-CoV-2/isolation & purification , Antibodies, Viral/blood , Antibody Formation , Asymptomatic Infections/epidemiology , COVID-19/epidemiology , COVID-19/virology , Cohort Studies , Female , Humans , London/epidemiology , Male , Middle Aged , SARS-CoV-2/immunology , Serologic Tests
13.
Crit Care Med ; 49(3): 428-436, 2021 03 01.
Article in English | MEDLINE | ID: covidwho-1057891

ABSTRACT

OBJECTIVES: Critical care workers were considered to be at high risk of severe acute respiratory syndrome coronavirus-2 infection from patients during the first wave of the pandemic. Staff symptoms, previous swab testing, and antibody prevalence were correlated with patient admissions to investigate this assumption. DESIGN: Cross-sectional study. SETTING: A large critical care department in a tertiary-care teaching hospital in London, United Kingdom. SUBJECTS: Staff working in critical care. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Participants completed a questionnaire and provided a serum sample for severe acute respiratory syndrome coronavirus-2 antibody testing over a 3-day period in April 2020. We compared the timing of symptoms in staff to the coronavirus disease 2019 patient admissions to critical care. We also identified factors associated with antibody detection. Of 625 staff 384 (61.4%) reported previous symptoms and 124 (19.8%) had sent a swab for testing. Severe acute respiratory syndrome coronavirus-2 infection had been confirmed in 37 of those swabbed (29.8%). Overall, 21% (131/625) had detectable severe acute respiratory syndrome coronavirus-2 antibody, of whom 9.9% (13/131) had been asymptomatic. The peak onset of symptoms among staff occurred 2 weeks before the peak in coronavirus disease 2019 patient admissions. Staff who worked in multiple departments across the hospital were more likely to be seropositive. Staff with a symptomatic household contact were also more likely to be seropositive at 31.3%, compared with 16.2% in those without (p < 0.0001). CONCLUSIONS: Staff who developed coronavirus disease 2019 were less likely to have caught it from their patients in critical care. Other staff, other areas of the hospital, and the wider community are more likely sources of infection. These findings indicate that personal protective equipment was effective at preventing transmission from patients. However, staff also need to maintain protective measures away from the bedside.


Subject(s)
COVID-19 Serological Testing , COVID-19/diagnosis , Critical Care , Health Personnel/statistics & numerical data , Personnel, Hospital/statistics & numerical data , Adult , COVID-19/transmission , Cross-Sectional Studies , Female , Humans , London/epidemiology , Male , Middle Aged , Patient Admission , SARS-CoV-2/pathogenicity , Tertiary Care Centers , United Kingdom/epidemiology
14.
J Infect ; 81(6): 931-936, 2020 12.
Article in English | MEDLINE | ID: covidwho-866901

ABSTRACT

BACKGROUND: Understanding of the true asymptomatic rate of infection of SARS-CoV-2 is currently limited, as is understanding of the population-based seroprevalence after the first wave of COVID-19 within the UK. The majority of data thus far come from hospitalised patients, with little focus on general population cases, or their symptoms. METHODS: We undertook enzyme linked immunosorbent assay characterisation of IgM and IgG responses against SARS-CoV-2 spike glycoprotein and nucleocapsid protein of 431 unselected general-population participants of the TwinsUK cohort from South-East England, aged 19-86 (median age 48; 85% female). 382 participants completed prospective logging of 14 COVID-19 related symptoms via the COVID Symptom Study App, allowing consideration of serology alongside individual symptoms, and a predictive algorithm for estimated COVID-19 previously modelled on PCR positive individuals from a dataset of over 2 million. FINDINGS: We demonstrated a seroprevalence of 12% (51 participants of 431). Of 48 seropositive individuals with full symptom data, nine (19%) were fully asymptomatic, and 16 (27%) were asymptomatic for core COVID-19 symptoms: fever, cough or anosmia. Specificity of anosmia for seropositivity was 95%, compared to 88% for fever cough and anosmia combined. 34 individuals in the cohort were predicted to be Covid-19 positive using the App algorithm, and of those, 18 (52%) were seropositive. INTERPRETATION: Seroprevalence amongst adults from London and South-East England was 12%, and 19% of seropositive individuals with prospective symptom logging were fully asymptomatic throughout the study. Anosmia demonstrated the highest symptom specificity for SARS-CoV-2 antibody response. FUNDING: NIHR BRC, CDRF, ZOE global LTD, RST-UKRI/MRC.


Subject(s)
Asymptomatic Infections/epidemiology , COVID-19/epidemiology , Adult , Aged , Aged, 80 and over , Anosmia/epidemiology , Antibodies, Viral/blood , COVID-19/blood , COVID-19/diagnosis , COVID-19/immunology , England/epidemiology , Enzyme-Linked Immunosorbent Assay , Female , Humans , Immunoglobulin G/blood , Immunoglobulin M/blood , Male , Middle Aged , Prospective Studies , SARS-CoV-2/immunology , SARS-CoV-2/isolation & purification , Seroepidemiologic Studies , Spike Glycoprotein, Coronavirus/immunology , Twins , Young Adult
16.
Thorax ; 75(12): 1082-1088, 2020 12.
Article in English | MEDLINE | ID: covidwho-717419

ABSTRACT

BACKGROUND: Accurate antibody tests are essential to monitor the SARS-CoV-2 pandemic. Lateral flow immunoassays (LFIAs) can deliver testing at scale. However, reported performance varies, and sensitivity analyses have generally been conducted on serum from hospitalised patients. For use in community testing, evaluation of finger-prick self-tests, in non-hospitalised individuals, is required. METHODS: Sensitivity analysis was conducted on 276 non-hospitalised participants. All had tested positive for SARS-CoV-2 by reverse transcription PCR and were ≥21 days from symptom onset. In phase I, we evaluated five LFIAs in clinic (with finger prick) and laboratory (with blood and sera) in comparison to (1) PCR-confirmed infection and (2) presence of SARS-CoV-2 antibodies on two 'in-house' ELISAs. Specificity analysis was performed on 500 prepandemic sera. In phase II, six additional LFIAs were assessed with serum. FINDINGS: 95% (95% CI 92.2% to 97.3%) of the infected cohort had detectable antibodies on at least one ELISA. LFIA sensitivity was variable, but significantly inferior to ELISA in 8 out of 11 assessed. Of LFIAs assessed in both clinic and laboratory, finger-prick self-test sensitivity varied from 21% to 92% versus PCR-confirmed cases and from 22% to 96% versus composite ELISA positives. Concordance between finger-prick and serum testing was at best moderate (kappa 0.56) and, at worst, slight (kappa 0.13). All LFIAs had high specificity (97.2%-99.8%). INTERPRETATION: LFIA sensitivity and sample concordance is variable, highlighting the importance of evaluations in setting of intended use. This rigorous approach to LFIA evaluation identified a test with high specificity (98.6% (95%CI 97.1% to 99.4%)), moderate sensitivity (84.4% with finger prick (95% CI 70.5% to 93.5%)) and moderate concordance, suitable for seroprevalence surveys.


Subject(s)
Antibodies, Viral/analysis , COVID-19/diagnosis , Immunoassay/methods , Pandemics , SARS-CoV-2/immunology , Adult , COVID-19/epidemiology , COVID-19/virology , DNA, Viral/analysis , Female , Follow-Up Studies , Humans , Male , Middle Aged , Reproducibility of Results , Retrospective Studies , SARS-CoV-2/genetics , Seroepidemiologic Studies
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