Roche Assay Research Articles

High prevalence of SARS-CoV-2 antibodies in pregnant women after the second wave of infections in the inner-city of Johannesburg, Gauteng Province, South Africa

ObjectivesAfter South Africa's second wave of COVID-19, this study estimated the SARS-CoV-2 seroprevalence among pregnant women in inner-city Johannesburg, South Africa. MethodsIn this cross-sectional survey, 500 pregnant women who were non-COVID-19-vaccinated (aged ≥12 years) were enrolled, and demographic and clinical data were collected. Serum samples were tested using the Wantai SARS-CoV-2 spike antibody enzyme-linked immunosorbent assay and Roche Elecsys® anti-SARS-CoV-2 nucleocapsid antibody assays. Seropositivity was defined as SARS-CoV-2 antibodies on either (primary) or both (secondary) assays. Univariate Poisson regression assessed risk factors associated with seropositivity. ResultsThe median age was 27.4 years, and HIV prevalence was 26.7%. SARS-CoV-2 seroprevalence was 64.0% (95% confidence interval [CI]: 59.6-68.2%) on the primary and 54% (95% CI: 49.5-58.4%) on the secondary measure. Most (96.6%) women who were SARS-CoV-2-seropositive reported no symptoms. On the Roche assay, we detected lower seroprevalence among women living with HIV than women without HIV (48.9% vs 61.7%, P-value = 0.018), and especially low levels among women living with HIV with a clusters of differentiation 4 <350 cells/ml compared with women without immune suppression (22.2% vs 56.4%, prevalence rate ratio = 0.4; 95% CI: 0.2-0.9; P-value = 0.046). ConclusionPregnant women attending routine antenatal care had a high SARS-CoV-2 seroprevalence after the second wave in South Africa, and most had asymptomatic infections. Seroprevalence surveys in pregnant women present a feasible method of monitoring the course of the pandemic over time.

Managing the impact of inter-method bias of prostate specific antigen assays on biopsy referral: the key to move towards precision health in prostate cancer management.

We assessed the inter-method bias of total (tPSA) and free (fPSA) prostate-specific antigen (PSA) immunoassays to establish if tPSA-based risk thresholds for advanced prostate cancer (PCa), obtained from one method (Roche) can be converted into the corresponding concentrations assayed by other methods. Then we evaluated the impact of the bias of tPSA and fPSA on theestimation of the %f/tPSA ratio and performed a re-calibration of the proposed thresholds for the %f/tPSA ratio according to the assay used. tPSA and fPSA were measured in 135 and 137 serum samples, respectively by Abbott Alinity i, Beckman Access Dxl, Roche Cobas e801, and Siemens Atellica IManalytical platforms. Scatterplots, Bland-Altman diagrams, Passing-Bablok (PB) were used to inspect and estimate the systematic and proportional bias between the methods. The linear equations with confidence intervals of the parameter estimates were used to transform the tPSA risk thresholds for advanced PCa into the corresponding concentrations measurable by the other analytical methods. To construct a correction coefficient for converting the %f/tPSA ratio from one method to the other, PB and non-parametric boostrapping were used. The inter-method bias is not constant but strictly linear allowing the conversion of PSA results obtained from Roche into the other assays, which underestimate tPSA vs. Roche. Siemens and Abbott vs. Roche and Beckman assays, being characterized by a positive and a negative proportional bias for tPSA and fPSA measurements, tend to overestimate the %f/tPSA ratio. There is a consistent risk to miss advanced PCa, if appropriate conversion factors are not applied.

PSAT055 ACTH-Dependent or ACTH-Independent: The Importance of a Reliable ACTH Assay in Solving a Case of Cushing Syndrome

Abstract Background Reliable laboratory assays are of paramount importance in the field of endocrinology, as our ability to make diagnoses and recommend the appropriate treatment, rely heavily on them. Clinical Case A 36-year-old woman presented to our clinic with a history of a 30-pound weight gain over the course of a year and hypertension that was sub-optimally controlled on two antihypertensive medications. On physical exam she exhibited facial plethora, moon facies, central obesity, dorsocervical fat pad, and reddish abdominal striae. Laboratory data revealed a 24 hr urine free cortisol 277 mcg/24 h (n ≤ 45 mcg/24 h), 8 am cortisol after 1 mg dexamethasone suppression test 19.2 mcg/dL (cut-off &amp;lt;1.8 mcg/dL) with a dexamethasone level 179 ng/dL (n 140-295 ng/dL). Serum DHEAS &amp;lt;15 mcg/dL (n 35-430 mcg/dL) which was suggestive of an adrenal source of cortisol. CT scan of the adrenals revealed a 3.0×2.3 cm right adrenal nodule, 14 HU, relative washout of 58%, absolute washout of 68%, consistent with an adenoma. However, plasma ACTH was 20 pg/mL (n 0-46 pg/mL) which was suggestive of an ACTH-dependent etiology. Repeat ACTH levels through our local lab ranged between 17-27 pg/mL. An MRI of the brain was obtained which showed a normal pituitary gland without evidence of an adenoma. Due to the discrepancy between the clinical picture and the ACTH levels, the patient's case was discussed with the medical director of our local lab. It was decided to obtain another sample for ACTH which was tested for heterophile antibodies but did not yield any meaningful results. The patient denied being on any supplements that could interfere with the ACTH assay. The sample was then sent out to an outside lab with a plasma ACTH level &amp;lt;1 pg/mL (n 7.2-63 pg/mL), which was consistent with the patient's clinical presentation of an adrenal source of cortisol excess. Further investigation revealed that our local lab used a Siemens Immulite assay which was likely detecting interference, whereas the outside lab used the Roche Elecsys assay. In previous studies, the Roche assay has highly correlated with intact ACTH that has been measured by HPLC-MS/MS. The patient was started on ketoconazole and has been referred for right adrenalectomy. Clinical Lessons Heterophile antibodies and ACTH fragments are common culprits of ACTH immunoassay interference, but they can be difficult to detect if there is not a high index of suspicion. Erroneous laboratory results can lead clinicians to perform unnecessary procedures and delay patient care. This case highlights the importance of a reliable plasma ACTH assay to inform clinical judgment. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.

LBMON65 Generation Of Serum Insulin Like Growth Factor -1 (IGF-1) Normative Data According To Age, Tanner Staging &amp; Bone Age In Healthy Indian Children And Adolescents With Two Different Assays: The Germinative Study

Abstract Context To diagnose and monitor GH-related disorders, serum IGF-I is a cornerstone, but Indian ethnicity based data, following consensus criteria for establishment of normative data are not available. Objectives To generate normative IGF-I data for chronological age (CA), Tanner stage and bone age (BA) [Greulich &amp; Pyle (GP)] for both genders. Setting and Participants: We conducted a cross-sectional epidemiological study for Indian children (age 5-18 years) that included 2226 apparently normal subjects (1145 males; 1081 females). We used robust clinical exclusion criteria initially and later statistically we removed outliers separately for Age,Tanner Stage &amp; Bone age using software SPSS 26. 0. Outcome Measures:: Serum IGF-I (ng/ml) using the Roche ECLIA &amp; Immunodiagnostic Systems &amp; Immunoassay System (IDS iSYS) were measured and normative data for 2.5th, 5th,10th, 25th, 50th (median), 75th, 90th, 95th and 97.5th centiles were generated. Results Age- and gender-specific serum IGF-I normative data generated from a uniquely large cohort reflected various patterns. With Roche assay, females (n=910) had IGF-I median peak at 13 years (356.85) [BA (n=804) at 14 years (401.5 ng/mL)] and &amp; Tanner (n = 936) stage IV (368) while males (n=959) had median peak at 14 years (329.5) [BA (n=906) at 15 years (351 ng/mL)] &amp; Tanner (n = 986) stage III (311. 0). With IDS iSYS assay, females had IGF-I median peak at Age (n=913) 13 years (397.5), Tanner (n=941) stage IV (418.5) and GP BA (n=843) 14 years (448.5) and males had median peak at Age (n=974) 14 years (376), Tanner (n=1003) stage III (367) and GP BA (n=909) 15-16 years (383). Females had earlier rise &amp; peak and higher IGF-I values with both assays. In Tanner-specific data maximum difference noticed between stage II and III in both genders with both assays. On comparison of both assays, IGF-1 median peak was achieved at similar ages and Tanner stage but all the values are higher with IDS iSYS assay. When reviewed published literature on Caucasians, females had IGF-I median peak at 15 years (300.1) and Tanner stage III (382.8) and males had median peak at 15 years (318.3) and Tanner stage IV (439). The Indian &amp; Caucasian IGF-1 normative data clearly demonstrates that every ethnicity has a unique pattern of growth. Conclusions The normative data on serum IGF-I are ethnicity-specific and it will improve the diagnostic utility of IGF-I in evaluation and management of growth disorders in Indian Children. Using both age- and Tanner stage-specific normative data simultaneously can improve diagnostic work-up. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

Unusual total anti-SARS-CoV-2 antibody kinetics observed during longitudinal monitoring after BNT162b2 vaccination

The present study aimed to clarify unusual total antibody kinetics in three female individuals observed during longitudinal monitoring of antibody response to BNT162b2 COVID-19 vaccine in 54 healthy volunteers. Total and IgG antibodies against the SARS-CoV-2 spike glycoprotein were measured using Roche and Abbott quantitative assays, respectively, a day before and 8, 71, 135 and 217 days after the second dose. Samples showing unusual kinetics were additionally tested with Beckman Coulter and Euroimmun IgG assays, as well as IgA assay. Antibody levels peaked 8 days after the second dose (total:2769 U/mL; IgG:20022 AU/mL) and declined to 611 U/mL (total) and 783 AU/mL (IgG), after 217 days. A delayed increase of total but not IgG antibodies evidenced in three females, was in two cases coupled with an increase in IgA antibodies. This study identified a previously unknown contribution of anti-SARS-CoV-2 IgA antibodies to a delayed total antibody increase in a subgroup of vaccinated individuals. It also emphasizes that different commercially available serological assays do not provide uniform information about the post-vaccination immune status and that thorough understanding the assays’ features is crucial for the proper interpretation of antibody response monitoring.

Comparison of the measured values of quantitative SARS-CoV-2 spike antibody assays.

BackgroundThe concentration of antibodies against the SARS-CoV-2 spike protein is frequently being measured for clinical and epidemiological purposes. The aim of this study was to examine whether the results of different quantitative SARS-CoV-2 spike antibody assays are comparable.Material and methodsThe Siemens SARS-CoV-2 IgG, Abbott SARS-CoV-2 IgG II Quant, Roche ElecsysT Anti-SARS-CoV-2 S, and Euroimmun Anti-SARS-CoV-2-QuantiVac assay were compared with 110 sera from patients 6-9 months after SARS-CoV-2 infection and the WHO First International SARS-CoV-2 antibody standard 20/136. The antibody values were converted into WHO binding antibody units (BAU)/ml. The diagnostic sensitivity of the assays was determined and the antibody values were compared.ResultsThe diagnostic sensitivity ranged from 57.3% (Euroimmun) to 100% (Roche). The antibody concentration values of different assays correlated with Pearson coefficients of correlation between 0.729 and 0.953. The geometric mean antibody values of the Abbott, Siemens and Euroimmun assay varied by a factor of 1.1-1.2. The geometric mean antibody values of the Roche assay were 2.4-2.8 times higher than those from the other assays. The assays yielded varying results with the WHO International antibody standard.ConclusionsThe quantitative SARS-CoV-2 antibody assays from Abbott, Siemens, Roche and Euroimmun correlate strongly but differ in the antibody concentrations. Therefore, the same assay should be used when testing patients repeatedly. In addition, the name of the assay used and the manufacturer should be indicated along with the test results.

Sensitivity of three antibody assays to SARS-CoV-2 nucleocapsid protein in relation to timing since diagnosis

The sensitivity of immunoassay for antibodies to SARS-CoV-2 may decrease over time. We compared three serology assays against SARS-CoV-2 nucleocapsid protein using serum samples of 20 health care workers with a history of mild PCR-confirmed coronavirus disease 2019 (COVID-19) at various timing since diagnosis. Overall, the sensitivity (95% confidence interval) was 95.0 (75.1-99.9), 60.0 (36.1-81.0), and 45.0 (23.1-68.5) for the Roche, Sysmex, and Abbott assays, respectively. The sensitivity of all these assays exceeded 80 for those diagnosed within 6 months, whereas it varied considerably for those diagnosed more than 6 months ago: 88.9 (Roche) versus 0 (Abbott). The present data provide a reference for researchers planning serological studies and interpreting these data. Such assay difference in terms of detection durability can be used, if used in combination, for the estimation of the timing of previously undetected infection.

Community seroprevalence of SARS-CoV-2 in children and adolescents in England, 2019–2021

ObjectiveTo understand community seroprevalence of SARS-CoV-2 in children and adolescents. This is vital to understanding the susceptibility of this cohort to COVID-19 and to inform public health policy for disease...

Multi-center evaluation of the highly sensitive Abbott ARCHITECT and Alinity thyroglobulin chemiluminescent microparticle immunoassay.

BackgroundThyroglobulin (Tg) is an essential part for the management of patients with differentiated thyroid carcinoma (DTC) after thyroidectomy. Highly sensitive Tg assays are now established in clinical practice as they facilitate follow‐up of DTC patients. In this study, we evaluated the recently launched highly sensitive Abbott Tg assay for Alinity and ARCHITECT.MethodsIn this three‐center study, Tg values of 447 routine patient samples, characterized for the presence of anti‐Tg, were measured with the ARCHITECT Tg assay and compared with the Roche Elecsys TgII assay. In addition, a subset of 154 samples was compared also with the Beckman Tg Access assay and another subset (n = 122) with Abbott Tg on the Alinity i analyzer.ResultsLoQ was verified to be less than or equal to 0.1 ng/ml confirming that the Tg assay on ARCHITECT and Alinity is highly sensitive. Correlation of ARCHITECT, Alinity, and Roche was excellent with a slope between 0.9 and 1.1 and a correlation coefficient >0.98. Correlation to Beckmann Tg was also very good, but the differences in absolute values were significant (slope: 1.477).ConclusionsThe Abbott Thyroglobulin assay, which is standardized to CRM‐457, demonstrated a high correlation to the Roche and Beckman Tg assays, though good agreement of absolute values was only observed between Abbott and Roche. Strength of correlation and slope were not affected by the presence of anti‐Tg indicating that all assays included in the study have a similar susceptibility to anti‐Tg.

Optimization of Patient Management in the Gynecology Emergency Department Using Point-of-Care Beta hCG.

Background: Point-of-care testing (POCT) provides shorter turn-around times and, in many cases, potentially improves medical decision making. The AQT90 FLEX® benchtop immunoanalyzer (Radiometer Medical ApS, Copenhagen, Denmark) allows for the determination of beta-human chorionic gonadotropin (βhCG) in 18 min. The main aim of this study was to evaluate the impact of measuring βhCG using the AQT90 analyzer in the gynecology emergency department (ED) compared to the standard practice of using central laboratory blood testing on the patient length of stay (LOS). Methods: The evaluation consisted of two parts. The first one, conducted in the central laboratory, focused on the analytical performances of the AQT βhCG assay. The second one, conducted in the ED, aimed at determining the impact of POCT βhCG implementation on the timeframe in which ED patients require βhCG assessment. Results: The within-lab imprecisions at the mean values of 17 and 287 IU/L were 2.7% and 3.7%, respectively. Using Deming regression (n = 60), the following equation was obtained in the central lab: AQT90 βhCG = 1.1 Roche βhCG—12.9 (r = 0.997). The implementation of POCT βhCG in the ED significantly reduced patient LOS (145 (90–212) min vs. 205 (155–265) with and without AQT90, respectively, p < 0.001). At the 2 IU/L decision level, a 99.7% agreement with the Roche assay was reported (kappa statistics, 0.99). Conclusions: We confirm that the analytical qualities of the AQT 90 were in line with those obtained in the central lab. The implementation of the POCT βhCG is associated with a shorter LOS in the ED due to the faster availability of the results and the faster decision-making possibilities.

The Common H202D Variant in GDF-15 Does Not Affect Its Bioactivity but Can Significantly Interfere with Measurement of Its Circulating Levels.

There is growing interest in the measurement of growth differentiation factor 15 (GDF-15) in a range of disorders associated with cachexia. We undertook studies to determine whether a common histidine (H) to aspartate (D) variant at position 202 in the pro-peptide (position 6 in the mature peptide) interfered with its detection by 3 of the most commonly used immunoassays. Three synthetic GDF-15-forms (HH homo-, HD hetero-, and DD-homodimers) were measured after serial dilution using Roche Elecsys®, R&amp;D QuantikineTM ELISA, and MSD R&amp;D DuoSet® immunoassays. GDF-15 concentrations were measured by the Roche and the MSD R&amp;D immunoassays in 173 genotyped participants (61 HH homozygotes, 59 HD heterozygotes, and 53 DD homozygotes). For the comparative statistical analyses of the GDF-15 concentrations, we used non-parametric tests, in particular Bland-Altman difference (bias) plots and Passing-Bablok regression. The bioactivity of the 2 different homodimers was compared in a cell-based assay in HEK293S-SRF-RET/GFRAL cells. The Roche assay detected H- and D-containing peptides similarly but the R&amp;D reagents (Quantikine and DuoSet) consistently underreported GDF-15 concentrations in the presence of the D variant. DD dimers had recoveries of approximately 45% while HD dimers recoveries were 62% to 78%. In human serum samples, the GDF-15 concentrations reported by the R&amp;D assay were a median of 4% lower for HH, a median of 36% lower for HD, and a median of 61% lower for DD compared to the Roche assay. The bioactivities of the HH and DD peptides were indistinguishable. The D variant of GDF-15 substantially affects its measurement by a commonly used immunoassay, a finding that has clear implications for its interpretation in research and clinical settings.

HIV viral load assays when used with whole blood perform well as a diagnostic assay for infants.

Over the past several years, only approximately 50% of HIV-exposed infants received an early infant diagnosis test within the first two months of life. While high attrition and mortality account for some of the shortcomings in identifying HIV-infected infants early and putting them on life-saving treatment, fragmented and challenging laboratory systems are an added barrier. We sought to determine the accuracy of using HIV viral load assays for infant diagnosis of HIV. We enrolled 866 Ugandan infants between March-April 2018 for this study after initial laboratory diagnosis. The median age was seven months, while 33% of infants were less than three months of age. Study testing was done using either the Roche or Abbott molecular technologies at the Central Public Health Laboratory. Dried blood spot samples were prepared according to manufacturer-recommended protocols for both the qualitative and quantitative assays. Viral load test samples for the Roche assay were processed using two different buffers: phosphate-buffered saline (PBS: free virus elution viral load protocol [FVE]) and Sample Pre-Extraction Reagent (SPEX: qualitative buffer). Dried blood spot samples were processed for both assays on the Abbott using the manufacturer's standard infant diagnosis protocol. All infants received a qualitative test for clinical management and additional paired quantitative tests. 858 infants were included in the analysis, of which 50% were female. Over 75% of mothers received antiretroviral therapy, while approximately 65% of infants received infant prophylaxis. The Roche SPEX and Abbott technologies had high sensitivity (>95%) and specificity (>98%). The Roche FVE had lower sensitivity (85%) and viral load values. To simplify and streamline laboratory practices, HIV viral load may be used to diagnose HIV infection in infants, particularly using the Roche SPEX and Abbott technologies.

Passive immunization against COVID-19 by anti-SARS-CoV-2 spike IgG in commercially available immunoglobulin preparations in severe antibody deficiency

Passive immunization against COVID-19 by anti-SARS-CoV-2 spike IgG in commercially available immunoglobulin preparations in severe antibody deficiency

Cross-reactivity in assays for prolactin and optimum screening policy for macroprolactinaemia.

Macroprolactin cross-reacts in immunoassays for prolactin causing apparent hyperprolactinaemia (macroprolactinaemia) and consequent misdiagnosis and mismanagement of patients. We determined the prevalence of macroprolactinaemia using prolactin immunoassays with reported "high" (Tosoh) or "low" cross-reactivity (Roche) with macroprolactin. We additionally modelled the effects of increasing the screening threshold on workload and sensitivity in the detection of macroprolactinaemia. A review of routine requests for prolactin received in a 12month period identified 670 sera with hyperprolactinaemia (Tosoh assay). Treatment with polyethylene glycol (PEG) precipitation demonstrated normal levels of monomeric prolactin in 165 sera (24.6%) indicating macroprolactinaemia. In the macroprolactinaemic cohort, total prolactin levels were lower with the Roche assay (473±132mU/L; mean±SD) compared to the Tosoh assay (683±217mU/L), p<0.005. The prevalence of macroprolactinaemia was also lower with the Roche assay (6.2%). The number of samples that required screening for macroprolactinaemia fell by 14% when Roche gender specific total prolactin reference limits were applied. Use of a higher screening threshold (700mU/L) reduced the screening workload considerably (Roche by 45%, Tosoh by 37%) however, the sensitivity of detection of macroprolactinaemia decreased markedly (Roche 90%, Tosoh 59%). Macroprolactin interferes in both Tosoh and Roche prolactin immunoassays. Use of an assay with a relatively low cross reactivity with macroprolactin, e.g. Roche, will lead to a modest reduction in the screening workload. Increasing the screening threshold above the upper limit of the assay reference interval will also reduce the screening workload but leads to disproportionate increases in the number of cases of macroprolactinaemia which are missed.

Performance of the Abbott Architect Immuno-Chemiluminometric NT-proBNP Assay.

Background: We evaluated the performance of the Abbott N-terminal pro-brain natriuretic peptide (NT-proBNP) assay against the Roche NT-proBNP immunoassay across two sites. Methods: Precision, linearity, and sensitivity studies were performed. A combined method of comparison and regression analysis was performed between the Roche and Abbott assays using samples from both sites (n = 494). To verify biotin interference, lyophilised biotin powder was reconstituted and spiked into serum samples at two medical decision levels (final concentration 500/4250 ng/mL) and compared to controls. NT-proBNP was also measured in anonymised leftover sera (n = 388) in a cardio-renal healthy population and stratified into three age bands—<50 (n = 145), 50–75 (n = 183) and >75 (n = 60). Results: Between-run precision (CV%) for NT-proBNP was 4.17/4.50 (139.5/142.0 pg/mL), 3.83/2.17 (521.6/506.3), and 4.60/2.51 (5053/4973), respectively. The assay was linear from 0.7–41,501 pg/mL. The limit of blank/quantitation was 1.2/7.9 pg/mL. The assay showed no interference from biotin up to 4250 ng/mL. Passing–Bablok regression analysis showed excellent agreement between the two assays (r = 0.999, 95% CI 0.999 to 0.999, p < 0.0001). The Roche assay had a slightly persistent, negative bias across different levels of NT-proBNP. ESC age cut-offs for diagnosing acute heart failure are applicable for the Abbott assay, with the median NT-proBNP of subjects < 50 years old at 43.0 pg/mL (range 4.9–456 pg/mL), 50–75 years old at 95.1 pg/mL (range 10.5–1079 pg/mL), and >75 years old at 173.1 pg/mL (range 23.2–1948 pg/mL). Conclusions: The Abbott Architect NT-proBNP assay has good performance that agrees with the manufacturer’s specifications. ESC/AHA recommended NT-proBNP age groups for acute heart failure diagnosis are applicable to this assay.

Frequency histograms of three high-sensitivity cardiac troponin assays in a reference population.

BackgroundCardiac troponin (cTn) values above the 99th percentile upper reference limit (URL) indicate myocardial injury. We established 99th percentile URLs for three high‐sensitivity cTn (hs‐cTn) assays (Beckman Coulter Access hs‐cTnI, Abbott STAT hs‐cTnI, and Roche Elecsys hs‐cTnT) using a healthy population in Korea.MethodsEach cTn value was measured by three assays and analyzed by dividing by gender and age.ResultsThe frequency histograms of log‐transformed cTn values for Beckman and Abbott assays exhibited a bell‐shaped distribution. The 99th percentile URLs were 9.8, 17.4, and 17.3 ng/L in the total population; 10.9/9.0, 18.9/17.0, and 18.9/17.7 ng/L in the male/female population (p < 0.001 for all three assays); and 11.2/7.2, 19.9/14.5, and 22.7/9.3 ng/L in the older/younger population (p < 0.001 for all three assays) for Beckman, Abbott, and Roche assays, respectively.ConclusionAmong the three assays, bell‐shaped distributions were observed in a frequency histogram of log‐transformed cTn values for healthy population in Beckman and Abbott assays. Also, our findings show that the 99th percentile URLs for cTn levels vary not only by gender but age.

Sociodemographic disparities in COVID-19 seroprevalence across England in the Oxford RCGP primary care sentinel network

ObjectivesTo monitor changes in seroprevalence of SARS-CoV-2 antibodies in populations over time and between different demographic groups.MethodsA subset of practices in the Oxford-Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC) sentinel network provided serum samples, collected when volunteer patients had routine blood tests. We tested these samples for SARS-CoV-2 antibodies using Abbott (Chicago, USA), Roche (Basel, Switzerland) and/or Euroimmun (Luebeck, Germany) assays, and linked the results to the patients’ primary care computerised medical records.We report seropositivity by region and age group, and additionally examined the effects of gender, ethnicity, deprivation, rurality, shielding recommendation and smoking status.ResultsWe estimated seropositivity from patients aged 18-100 years old, which ranged from 4.1% (95% CI 3.1–5.3%) to 8.9% (95% CI 7.8–10.2%) across the different assays and time periods. We found higher Euroimmun seropositivity in younger age groups, people of Black and Asian ethnicity (compared to white), major conurbations, and non-smokers. We did not observe any significant effect by region, gender, deprivation, or shielding recommendation.ConclusionsOur results suggest that prior to the vaccination programme, most of the population remained unexposed to SARS-CoV-2.

Association of ABO Blood Group, Age, Body Mass Index and Symptomatic COVID-19 Infection with Signal Levels of Antibodies to COVID-19

Objective: To determine if ABO blood group, age, body mass index (BMI), or symptomatic COVID-19 infection are associated with COVID-19 antibody response in unvaccinated COVID-19 antibody positive pregnant women at time of delivery. Methods: At the time of delivery, 2,499 consecutive pregnant women were tested for ABO blood group and antibodies to both the spike protein and nucleocapsid protein of the COVID-19 virus. The DiaSorin assay was used for antibody to spike protein analysis and the Roche assay for antibody to nucleocapsid protein. Gamma regression models with a log link were used to compare antibody signals, with blood group, age, and BMI as the predictors. Results: 260 (10.4%) of 2,499 women who had not been vaccinated for COVID-19, were positive for both spike and nucleocapsid protein antibodies to COVID-19. The mean signal for COVID-19 nucleocapsid antibody was significantly lower for blood group AB (p=0.028) compared with blood group O. A relationship between blood group and presence of symptomatic COVID-19 was detected (p = 0.028), with asymptomatic individuals having blood group B at a higher rate than the symptomatic individuals do. No other significant pairwise differences between blood groups were detected. There was no significant difference in signal level of antibodies to COVID-19 spike protein between any of the blood groups. Mean signals for antibodies to spike and nucleocapsid proteins were significantly higher in older women (p=0.001 for spike protein antibody and p=0.002 for nucleocapsid antibody). Significantly higher signal levels of antibody to spike and nucleocapsid proteins were found in women with class 2/3 obesity (p=0.022 and p=0.003, respectively). Conclusions: Pregnant women of AB blood group had lower antibody signal to nucleocapsid protein compared to the O blood group, and women of older age and greater BMI had higher antibody signal to COVID-19 spike and nucleocapsid proteins. There was a significant association between women with blood group B and asymptomatic infections.

Clinical concordance assessment should be an integral component of laboratory method comparison studies: A regression transference of routine clinical data approach

Manufacturer-provided assay-specific reference intervals may not compensate for between assay differences leading to method related clinical discordance. Not all laboratories, however, assess clinical concordance as part of method comparison studies. We assessed the utility of method comparison data combined with routine clinical data to assess method related clinical concordance in the diagnosis and management of subclinical hypothyroidism (SCH).Passing-Bablok method comparison regression analysis was performed for both thyroid stimulating hormone (TSH) and free thyroxine (fT4) from 100 samples analysed by Abbott and Roche methods. Primary care samples indicative of SCH were identified from the laboratory information system (LIMS) of two laboratories (one with Roche methods and one with Abbott) over four months. For Roche and Abbott TSH and fT4 results, the Passing-Bablok regression equations were used to predict Abbott and Roche results respectively. The predicted results were interpreted using manufacturer-provided assay-specific reference intervals and compared to those of the previous SCH sample exchange study.On laboratory method comparison, Roche TSH and fT4 results were 30 ± 13% and 16 ± 7% higher compared to Abbott assays respectively. Of those with results indicative of SCH by Roche assays, 76.8% would have had normal thyroid function using predicted Abbott assay results and 46.9% of those with results indicative of SCH by Abbott assays would have had a biochemical indication for levothyroxine replacement using predicted Roche assay results. The results from the regression-based approach were comparable to the previous SCH sample exchange study.A regression-based approach using routine method comparison data and real-world clinical data identifies potential clinical discordance. We suggest that clinical concordance assessment be an integral component of laboratory method comparison studies.

Six-month Antibody Kinetics and Durability After 3 Doses of SARS-CoV-2 Vaccine in Solid Organ Transplant Recipients: A Case Series.

Six-month Antibody Kinetics and Durability After 3 Doses of SARS-CoV-2 Vaccine in Solid Organ Transplant Recipients: A Case Series.