Journal of Clinical Virology Plus

The performance of the Roche Elecsys(R) Anti-SARS-CoV-2, Abbott Architect SARS-CoV-2 IgG, Euroimmun SARS-CoV-2 IgA, Euroimmun SARS-CoV-2 IgG ELISA, and Trillium IgG/IgM rapid assays was evaluated in Jamaica, the largest country of the English-speaking Caribbean. Diagnostic sensitivities of the assays were assessed by testing serum samples from SARS-CoV-2 PCR-confirmed persons. Serum samples collected [≥]14 days after onset of symptoms, or [≥]14 days after an initial SARS-CoV-2 RT-PCR positive test for asymptomatics, showed diagnostic sensitivities ranging from 67.9-75.0% when including all possible disease severities and increased to 90.0-95.0% when examining those with moderate to critical disease. Grouping moderate to critical disease showed a significant association with a SARS-CoV-2 antibody positive result for all assays. Diagnostic specificity, assessed by testing serum samples collected during 2018-2019 from healthy persons and from persons with antibodies to a wide range of viral infections, ranged from 96.7-100.0%. For all assays examined, SARS-CoV-2 real-time PCR cycle threshold (Ct) values of the initial nasopharyngeal swab sample testing positive were significantly different for samples testing antibody positive versus negative. These data from a predominantly African descent Caribbean population shows comparable diagnostic sensitivities and specificities for all testing platforms assessed and limited utility of these tests for persons with asymptomatic and mild infections.

BACKGROUNDChildren ([&le;]18 years) account for [~]20% of the US population but currently represent <2% of coronavirus disease 2019 (COVID-19) cases. Because infected children often have few or no symptoms and may not be tested, the extent of infection in children is poorly understood. METHODSDuring the March 18th-May 15th 2020 Louisiana Stay At Home Order, 1690 blood samples from 812 individuals from a Childrens Hospital were tested for antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein. Demographics, COVID-19 testing, and clinical presentation abstracted from medical records were compared with local COVID-19 cases. RESULTSIn total, 62 subjects (7.6%) were found to be seropositive. The median age was 11 years with 50.4% female. The presenting complaint of seropositive patients was chronic illness (43.5%). Only 18.2% had a previous positive COVID-19 PCR or antibody test. Seropositivity was significantly associated with parish (counties), race, and residence in a low-income area. Importantly, seropositivity was linearly correlated with cumulative COVID-19 case number for all ages by parish. CONCLUSIONIn a large retrospective study, the seropositivity prevalence for SARS-CoV-2 in children in Louisiana during the mandated Stay At Home Order was 7.6%. Residence location, race, and lower socioeconomic factors were linked to more frequent seropositivity in children and correlated to regional COVID-19 case rates. Thus, a significant number of children in Louisiana had SARS-CoV-2 infections that went undetected and unreported and may have contributed to virus transmission.

BackgroundMore than one million infections with the severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) have been confirmed. While PCR-based assays are used for diagnosis, high through-put serologic methods are needed to detect antibodies for seroserveillance and for identification of seroconversion, potential plasma donors, and the nature of the immune response to this pathogen. MethodsA Luminex binding assay was used to assess the presence of antibodies in human sera from COVID-19-infected and -uninfected individuals specific for two recombinant proteins of SARS-CoV-2. FindingsFluorochrome-labeled beads were coated with a recombinant soluble stabilized trimeric SARS-CoV-2 S protein ectodomain or its central portion, the receptor binding domain (RBD). Coated beads were incubated with sera, followed by incubation with biotinylated anti-human total Ig antibodies and phycoerythrin (PE)-labeled streptavidin. Readout using a Luminex analyzer clearly differentiated between sera of the infected and uninfected subjects, delineating a wide range of serum antibody levels in infected subjects. InterpretationAntibody assays of sera can identify individuals who are infected with SARS-CoV-2 and have seroconverted, as well as subjects who have been infected and recovered. The use of the Luminex binding Ab assay has the advantage that it can be run in approximately 2.5 hours, uses very little antigen, and permits a high through-put of samples/day. FundingNIAID contracts and grants, Department of Veterans Affairs grants, the Microbiology Laboratory Clinical Services, Translational Science Hub, and Personalized Virology Initiative, and Department of Medicine of Mount Sinai Health System and Icahn School of Medicine at Mount Sinai. RESEARCH IN CONTEXTO_ST_ABSEvidence before this studyC_ST_ABSThe outbreak of infections with SARS-CoV-2 began in late 2019. Specimens from nasopharyngeal swabs are being used in PCR-based assays to test for the presence of the virus. Until the first week in April, 2020 there were no licensed tests for the presence of serum antibodies against proteins of the virus. The first approved tests are now becoming available, but none use a format that can be scaled up for mass screening which is now needed for implementing various public health measures. As per a recent Pubmed search, less than 10 studies using serologic assays have been published and none are high through-put. Added value of this studyHigh through-put antibody tests are needed in order to identify seroconversion, to perform serosurveys, identify potential donors for plasma therapy, assess the prevalence of infection in populations, identify healthcare workers who may be immune to SARS-CoV-2, and to study the nature of the immune response to this pathogen. The method described for detecting antibodies in SARS-CoV-2-infected patients can be applied in hospital and reference labs, allowing the assessment of present and past infection in a much higher number of donors per unit of time than assays described heretofore. Implications of all the available evidenceThis study shows that a test in which magnetic beads are coated with soluble forms of the spike protein of SARS-CoV-2 can be used to test for the presence of antibodies targeting this pathogen. The platform allows for the efficient testing of multiple specimens simultaneously using as little as 5 nanograms of antigen per test. This test affords the possibility of large scale, economical and efficient antibody testing.

Highly pathogenic avian influenza (HPAI) H5N1 has been a global concern since its emergence in 1997, causing widespread outbreaks in birds and sporadic human infections. The clade 2.3.4.4b H5N1 virus has rapidly expanded across continents, infecting numerous mammalian species. In 2024, it was detected in dairy cattle for the first time in the U.S., along with human cases following exposure. In Canada, the first human case of this avian influenza was reported in a critically ill adolescent in late 2024. No human-to-human transmission has been documented, but concerns persist regarding mutations associated with enhanced virulence and human adaptation. Although seasonal influenza vaccines are not directed against H5N1, studies suggest that pre-existing immunity from prior infections or vaccinations may provide partial protection against severe H5N1 infections through cross-reactive immune response. Given the ongoing circulation of avian influenza and the rise in human infections, this study evaluated the effectiveness of neutralizing antibodies developed against seasonal influenza viruses and their cross-reactivity with recent H5N1 strains. Serum samples from 194 retail sector workers in Quebec, collected between late 2021 and 2022, were analyzed using a microneutralization assay. While strong neutralizing activity was found against seasonal influenza viruses, no neutralizing antibodies were detected against H5N1 strains in either vaccinated or unvaccinated individuals. These findings emphasize the need to evaluate cross-reactive antibodies against the neuraminidase protein of H5N1, assess cellular immune responses potentially linked to protection against severe HPAI H5N1 infections and targeted vaccine strategies against recently emerged H5N1 influenza viruses.

The reliable detection of immunoglobulin G (IgG) or total antibodies directed against the novel severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is important for clinical diagnostics and epidemiological studies. Here, we compare the diagnostic accuracy of six commercially available SARS-CoV-2 IgG (Abbott SARS-CoV-2 IgG; Diasorin Liaison(R) SARS-CoV-2 S1/2 IgG; Epitope EDI Novel Coronavirus COVID-19 IgG ELISA Kit; Euroimmun Anti-SARS-CoV-2 ELISA (IgG); Mikrogen recomWell SARS-CoV-2 IgG) or total SARS-CoV-2 antibody assays (Roche Elecsys Anti-SARS-CoV-2). The test sensitivities were analyzed with a set of 34 sera obtained from 26 patients after PCR-confirmed SARS-CoV-2 infection and varied from 76.9% (Euroimmun) to 96.2% (Abbott). The majority of assay results were confirmed in a laboratory-developed plaque reduction neutralization test and by a SARS-CoV-2 IgG-specific line assay including measurement of generally low IgG avidities (Mikrogen recomLine Coronavirus IgG [Aviditat], prototype). Moreover, 100 stored sera collected during summer 2018 (N = 50) and winter season 2018/2019 (N = 50) were included to demonstrate test specificities. These varied from 96.0% (DiaSorin) to 100% (Epitope EDI). A subset of sera were retested with a lateral flow test (STANDARD Q COVID-19 IgM/IgG Duo) and a considerably lower sensitivity was noted. Overall, the diagnostic accuracy of the six SARS-CoV-2 IgG/total antibody assays was good and varied from 92.9% (Euroimmun) to 98.4% (Abbott). Due to the different specificities, results of commercially available SARS-CoV-2 antibody tests should be interpreted with caution. A high proportion of antibody-positive patient sera demonstrated neutralizing capacity against SARS-CoV-2.

BackgroundThe severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Delta lineage (B.1.617.2) was implicated in the SARS-CoV-2 surge in India. We sought to describe the rapid expansion of the Delta lineage in Ontario, Canada (population 15 million) using mutation profile information and confirmatory whole genome sequencing. MethodsAll laboratory-confirmed SARS-CoV-2 cases reported to Public Health Ontario between April 1st and June 12th 2021, with cycle threshold values [&le;]35, were eligible for screening for the N501Y and the E484K mutations. We classified cases via mutation screening as: (1) N501Y-/E484K- (wild-type/Delta), (2) Alpha (N501Y+/E484K-), (3) Beta/Gamma (N501Y+/E484K+), or (4) N501Y-/E484K+ (predominantly B.1.525, and B.1.1.318). ResultsThe N501Y-/E484K- mutation profile went from having a 29% transmission deficit relative to Alpha (relative Re = 0.71, 95%CI: 0.64, 0.77) on April 1st to having a 50% transmission advantage on June 12th (relative Re = 1.50, 95%CI: 1.31, 1.71). Whole genome sequencing of N501Y-/E484K-cases (N=583) confirmed that the pattern of increasing relative reproduction number coincided with the replacement of wild-type with Delta variant (from 2.2% in early April, to 83% in late May). DiscussionDelta is rapidly overtaking other SARS-CoV-2 variants in Ontario, and has a substantial transmission advantage. An inflection in the proportion of cases missing the N501Y mutation from rapidly decreasing to rapidly increasing,3 may be an early warning signal for Delta lineage expansion.

BackgroundSeveral serological assays have been developed to detect anti-SARS-CoV-2 IgG antibodies, but evidence about their comparative performance is limited. We sought to assess the sensitivity of four anti-SARS-CoV-2 IgG enzyme-linked immunosorbent assays (ELISA) in individuals with evidence of prior SARS-CoV-2 infection. MethodsWe obtained sera from 36 individuals with PCR-confirmed SARS-CoV-2 infection between March and May 2020. We evaluated samples collected at around 21 days ({+/-}14 days) after their initial PCR test using 3 commercially available ELISA assays, two anti-spike (Ortho- Clinical Diagnostics Vitros, and Euroimmun) and one anti-nucleocapsid (Abbott Architect), and a Yale-developed anti-spike ELISA test. We determined the sensitivity of the tests and compared their results. The Euroimmun and Yale ELISA had an equivocal and indeterminate category, which were considered as both negative and positive. ResultsAmong the 36 individuals with SARS-CoV-2 infection, mean age was 43 ({+/-}13) years and 19 (53%) were female. The sensitivities of the tests were not significantly different (Abbott Architect, Ortho Vitros, Euroimmmun, and Yale assays: 86% (95% confidence interval [CI], 71- 95), 94% (95% CI, 81-99), 86% (95% CI, 71-95), and 94% (95% CI, 81-99), respectively; p- value=0.464). The sensitivities of the Euroimmun and Yale ELISA tests increased when the equivocal/indeterminate results were considered positive (97% [95% CI, 85-100] and 100% [95% CI, 90-100], respectively), but were not significantly different from other tests (p=0.082). The cross-correlation coefficient ranged from 0.85-0.98 between three anti-spike protein assays (Ortho Vitros, Euroimmun, Yale) and was 0.58-0.71 between the three anti-spike protein assays and the anti-nucleocapsid assay (Abbott). ConclusionThe sensitivities of four anti-SARS-CoV-2 protein assays did not significantly differ, although the sample size was small. Sensitivity also depended on the interpretation of equivocal and indeterminate results. The strongest correlations were present for the three anti- spike proteins assays. These findings suggest that individual test characteristics and the correlation between different tests should be considered when comparing or aggregating data across different populations studies for serologic surveillance of past SARS-CoV-2 infection.

SARS-CoV-2 seroprevalence in an antenatal population in Kingston, Jamaica was assessed for September-November 2020 in a repeated cross-sectional study using the Abbott Architect SARS-CoV-2 IgG assay. After adjusting for test performance, seroprevalence was 6.9% for September, 16.9% for October, and 24.0% for November. Of the 37 pregnant women testing SARS-CoV-2 IgG positive, only 3 were symptomatic. One symptomatic woman testing SARS-CoV-2 IgG positive had multiple co-morbidities and succumbed to COVID-19 pneumonia. Up to January 31, 2021, 8 women identified as SARS-CoV-2 IgG positive delivered, all without complications. Comparison of test adjusted seroprevalence data with cumulative PCR-confirmed COVID-19 cases within the Kingston Metropolitan Area indicated that as many as 44.4 times more people were infected with SARS-CoV-2 than identified with PCR testing. These findings provide the first evidence for the extent of SARS-CoV-2 infections in Jamaica and will inform future SARS-CoV-2 testing strategies.

BackgroundWith the impact of SARS-CoV-2 upon public health directly and socioeconomically, further information was required to inform policy decisions designed to limit virus spread. This study sought to contribute to serosurveillance work within Northern Ireland to track SARS-CoV-2 progression and guide health strategy. MethodsSera/plasma samples from clinical biochemistry laboratories were analysed for anti-SARS-CoV-2 immunoglobulins (Ig). Samples were assessed using an Elecsys anti-SARS-CoV-2 or anti-SARS-CoV-2 S ECLIA (Roche) on an automated Cobas-e-analyser. Samples were also assessed via ELISA (Euroimmun). A subset of samples assessed via Roche Elecsys anti-SARS-CoV-2 IgG assay were subsequently analysed in an ACE2 pseudoneutralisation assay using a V-PLEX SARS-CoV-2 Panel 7 for IgG and ACE2 by MesoScale Diagnostics Inc. ResultsAcross three testing rounds (June-July 2020, November-December 2020 and June-July 2021 (rounds 1-3 respectively)), 4844 residual sera/plasma specimens were assayed for SARS-CoV-2 Ig. Seropositivity rates increased across the study, peaking at 11.6% during round 3. Varying trends in SARS-CoV-2 seropositivity were noted based on demographic factors. For instance, highest rates of seropositivity shifted from older to younger demographics across the study period. In round 3, alpha (B.1.1.7) variant neutralising antibodies were most frequently detected across age groups, with median concentration of anti-spike protein antibodies elevated in 50-69 year olds and anti-S1 RBD antibodies elevated in over 70s, relative to other age groups. ConclusionsWith seropositivity rates of <15% across the assessment period, it can be concluded that the significant proportion of the Northern Ireland population had not yet naturally contracted the virus by mid-2021.

BackgroundThe introduction of vaccination against SARS-CoV-2 infection needs precise instruments for quality control of vaccination procedure, detection of poor immunological response and estimation of the achieved protection against the disease but also against infection and being infective. ObjectiveTo compare new automated SARS-CoV 2 Ig assay performance characteristics from the automated Elecsys SARS-CoV-2 S (Roche) with the new LIAISON(R) SARS-CoV-2 TrimericS IgG (DiaSorin) assay and their compatibility with WHO International Standard for anti-SARS-CoV-2 immunoglobulin. In the context of the mass vaccination programs, we undertook the investigation of clinical utility of the two new automated assays by analyzing results in samples collected at specified time points relative to the vaccination time. DesignProspective assay evaluation. PatientsMedical staff undergoing vaccination with BioNTech/Pfizer Comirnaty vaccine between January and March 2021 (n = 79) and referred for serum antiSARS-CoV 2 Ig testing prior to vaccination, 21 days after the first dose, and 8, 14 and 30 days after the second dose. Main Outcome Measure(s): Serum antibody levels measured with Roche and DiaSorin assays. ResultsIntra-assay imprecision was low with DiaSorin at 3.46%; and Roche at 2.5%. The Passing-Bablok regression equation for all tested samples was y (DiaSorin) = 184.61 + (1.03 x Roche) and the correlation between the assays (r=0.587; p < 0.0001). ConclusionsThe novel automated assays exhibit strong concordance in calibration, with assay-specific interpretation required for routine clinical use. These results highlight the need for further work on the international standard of measurement of SARS-CoV 2 Ig especially in era of vaccination. The serological assays can be useful to detect IgG/IgM antibodies, to assess the degree of immunization, to trace the contacts, and to support the decision to readmit people to work or vaccinate them again. However, the values generated by both assays can be markedly different, and assay-specific and personalized interpretation is required.

Hemagglutination inhibition (HI) and neuraminidase inhibition (NI) antibodies to a clade 2.3.4.4b A(H5N1) highly pathogenic avian influenza virus were measured in 63 age-stratified healthy adults in Hong Kong. No HI antibody was detected; 61 subjects had detectable NI antibodies to A(H5N1). NI titers to A(H5N1) and A(H1N1)pdm09 viruses were correlated.

Serological SARS-CoV-2 assays are needed to support clinical diagnosis and epidemiological investigations. Recently, assays for the large-volume detection of total antibodies (Ab) and immunoglobulin (Ig) G and M against SARS-CoV-2 antigens have been developed, but there are limited data on the diagnostic accuracy of these assays. This study was organized as a Danish national collaboration and included fifteencommercial and one in-house anti-SARS-CoV-2 assays in sixteen laboratories. Sensitivity was evaluated using 150 serum samples from individuals diagnosed with asymptomatic,mild or moderate nonhospitalized (n=129) or hospitalized (n=31) COVID-19, confirmed bynucleic acid amplification tests, collected 13-73 days from symptom onset. Specificity and cross-reactivity were evaluated in samples collected prior to the SARS-CoV-2 epidemic from > 586 blood donors and patients with autoimmune diseases or CMV or EBV infections. Predefined specificity criteria of [&ge;] 99% were met by all total-Ab and IgG assays except one (Diasorin/LiaisonXL-IgG 97.2%). The sensitivities in descending order were: Wantai/ELISA total-Ab (96.7%), CUH/NOVO in-house ELISA total-Ab (96.0%), Ortho/Vitros total-Ab (95.3%), YHLO/iFlash-IgG (94.0%), Ortho/Vitros-IgG (93.3%), Siemens/Atellica total-Ab (93.2%), Roche-Elecsys total-Ab (92.7%), Abbott-Architect-IgG (90.0%), Abbott/Alinity-IgG (median 88.0%), Diasorin/LiaisonXL-IgG (84.6%),Siemens/Vista total-Ab (81.0%), Euroimmun/ELISA-IgG (78.0%), and Snibe/Maglumi-IgG (median 78.0%). The IgM results were variable, but one assay (Wantai/ELISA-IgM) hadboth high sensitivity (82.7%) and specificity (99%). The rate of seropositivity increased with time from symptom onset and symptom severity. In conclusion, predefined sensitivity and specificity acceptance criteria of 90%/99%, respectively, for diagnostic use were met in five of six total-Ab and three of seven IgG assays.

There is an urgent need for reliable high-throughput serological assays for the management of the ongoing COVID-19 pandemic. Preferably, the performance of serological tests for a novel virus should be determined with clinical specimens against a gold standard, i.e. virus neutralisation. We evaluated specificity and sensitivity of six commercial immunoassays for the detection of SARS-CoV-2 IgG, IgA and IgM antibodies, including four automated assays [Abbott SARS-COV-2 IgG (CE marked), Diasorin Liaison(R) SARS-CoV-2 S1/S2 IgG (research use only), and Euroimmun SARS-CoV-2 IgG and IgA (CE marked)], and two rapid lateral flow (immunocromatographic) tests [Acro Biotech 2019-nCoV IgG/IgM (CE marked) and Xiamen Biotime Biotechnology SARS-CoV-2 IgG/IgM (CE marked)] in comparison with a microneutralisation test (MNT). Two specimen panels from serum samples sent to Helsinki University Hospital Laboratory (HUSLAB) were compiled: the patient panel included sera from PCR confirmed COVID-19 patients, and the negative panel included sera sent for screening of autoimmune diseases and respiratory virus antibodies in 2018 and 2019. The MNT was carried out for all COVID-19 samples (70 serum samples, 62 individuals) and for 53 samples from the negative panel. Forty-one out of 62 COVID-19 patients showed neutralising antibodies with median of 11 days (range 3-51) after onset of symptoms. The specificity and sensitivity values of the commercial tests against MNT, respectively, were as follows: 95.1%/80.5% (Abbott Architect SARS-CoV-2 IgG), 94.9%/43.8% (Diasorin Liaison SARS-CoV-2 IgG), 68.3%/87.8% (Euroimmun SARS-CoV-2 IgA), 86.6%/70.7% (Euroimmun SARS-CoV-2 IgG), 74.4%/56.1% (Acro 2019-nCoV IgG), 69.5%/46.3% (Acro 2019-nCoV IgM), 97.5%/71.9% (Xiamen Biotime SARS-CoV-2 IgG), and 88.8%/81.3% (Xiamen Biotime SARSCoV-2 IgM). This study shows variable performance values. Laboratories should carefully consider their testing process, such as a two-tier approach, in order to optimize the overall performance of SARS-CoV-2 serodiagnostics.

Limited data are available for pregnant women affected by SARS-CoV-2. Serological tests are critically important to determine exposure and immunity to SARS-CoV-2 within both individuals and populations. We completed SARS-CoV-2 serological testing of 1,293 parturient women at two centers in Philadelphia from April 4 to June 3, 2020. We tested 834 pre-pandemic samples collected in 2019 and 15 samples from COVID-19 recovered donors to validate our assay, which has a [~]1% false positive rate. We found 80/1,293 (6.2%) of parturient women possessed IgG and/or IgM SARS-CoV-2-specific antibodies. We found race/ethnicity differences in seroprevalence rates, with higher rates in Black/non-Hispanic and Hispanic/Latino women. Of the 72 seropositive women who also received nasopharyngeal polymerase chain reaction testing during pregnancy, 46 (64%) were positive. Continued serologic surveillance among pregnant women may inform perinatal clinical practices and can potentially be used to estimate seroprevalence within the community. One Sentence SummarySix percent of pregnant women delivering from April 4 to June 3, 2020 had serological evidence of exposure to SARS-CoV-2 with notable race/ethnicity differences in seroprevalence rates.

IntroductionNon-pharmacologic interventions (NPIs), such as universal masking, implemented during the SARS-CoV-2 pandemic have reduced respiratory infections among children. This study focuses on evaluating the impact of NPIs on Mycoplasma pneumoniae infections in children, analyzing data from two hospitals in Arkansas, and examining age-related differences and coinfections with other viruses. MethodsThe study was approved by the Institutional Review Board and included patients aged [&le;]18 years with upper respiratory tract symptoms. Data from the FilmArray(R) Respiratory Panel (FARP) were collected and divided into pre-NPI and NPI periods for analysis. Total test positivity rate and interval change in the positivity rate were evaluated. Statistical differences were determined by Chi-square ({chi}2-independence) analysis. ResultsA total of 68,949 tests were performed with a statistical increase in testing during the NPI period. The overall test positivity rate for M. pneumoniae decreased by 74% (0.86% to 0.03%) during the NPI period, and the preschool age group had the highest number of positive tests in the pre- and NPI periods (Pre-NPI: n=40, NPI: n=12 positive tests, p=<0.001). The reduction in M. pneumoniae infections was consistent across age groups. Coinfections with other respiratory viruses, particularly human rhinovirus/enterovirus, were observed at much lower levels. ConclusionsNPIs effectively reduced M. pneumoniae in pediatric patients in Arkansas, and coinfections with specific viruses still occurred, albeit at lower levels during the SARS-CoV-2 pandemic. As NPIs are relaxed and the pandemic ends, we expect M. pneumoniae infections to return to pre-pandemic levels within the next 1-2 years.

A novel variant of SARS-CoV-2, B.1.1.7, originally discovered in the United Kingdom (UK), is rapidly overtaking other strains around the globe. In certain assays, absence of detection of the S-gene target, also known as S-gene target failure (SGTF) can be a sensitive surrogate of B.1.1.7. We analyzed daily counts of SGTF among samples from Dynacare Laboratory Ontario (which draws samples from the Greater Toronto Area) and resulted between December 16, 2020 and February 3, 2021. We identified 11,485 positive COVID-19 tests, of which 448 had SGTF (3.9%). The estimated prevalence of SGTF rose from 2.0% on December 16 to 15.2% on February 3 (1.8-fold weekly increase, 95%CI: 1.5, 2.2). The estimated reproduction number for SGTF cases was 1.17 (95%CI: 0.94 to 1.46), while the reproduction number for non-SGTF cases was 0.82 (95%CI: 0.65 to 1.01); the relative reproduction number was 1.44 (95%CI: 1.03, 1.99). 59 samples were sent for confirmatory testing, of which 53 (90%) were identified as B.1.1.7 using whole genome sequencing or found to have the N501Y mutation. In order to pre-emptively plan and implement public health measures to control COVID-19 now and through the spring, accurate and up-to-date early warning systems for new variants, including B.1.1.7, are essential across North America and the globe.

An epidemic caused by an outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in China in December 2019 has since rapidly spread internationally, requiring urgent response from the clinical diagnostics community. We present a detailed overview of the clinical validation and implementation of the first laboratory-developed real-time reverse-transcription-PCR (rRT-PCR) test offered in the NewYork-Presbyterian Hospital system following the emergency use authority (EUA) guidance issued by the US Food and Drug Administration. Validation was performed on nasopharyngeal and sputum specimens (n=124) using newly designed dual-target rRT-PCR (altona RealStar(R) SARS-CoV-2 Reagent) for detecting of SARS-CoV-2 in upper respiratory and lower respiratory tract specimens, including bronchoalveolar lavage and tracheal aspirates. Accuracy testing demonstrated excellent assay agreement between expected and observed values. The limit of detection (LOD) was 2.7 and 23.0 gene copies/reaction for nasopharyngeal and sputum specimens, respectively. Retrospective analysis of 1,694 tests from 1,571 patients revealed increased positivity in older patients and males compared to females, and an increasing positivity rate from approximately 20% at the start of testing to 50% at the end of testing three weeks later. Our findings demonstrate that the assay accurately and sensitively identifies SARS-CoV-2 in multiple specimen types in the clinical setting and summarizes clinical data from early in the epidemic in New York City.

BackgroundThe Elecsys(R) Anti-SARS-CoV-2 immunoassay (Roche Diagnostics) was developed to provide an accurate and reliable method for the detection of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We evaluated the specificity of the Elecsys Anti-SARS-CoV-2 immunoassay in prepandemic sample cohorts across five sites in Germany, Austria and Switzerland. MethodsSpecificity of the immunoassay was evaluated using anonymised, frozen, residual serum and/or plasma samples from blood donors or routine diagnostic testing. All samples were collected before September 2019 and therefore presumed negative for SARS-CoV-2-specific antibodies. Cohorts included samples from blood donors, pregnant women and paediatric patients. Point estimates and 95% confidence intervals (CIs) were calculated. ResultsOverall specificities for the Elecsys Anti-SARS-CoV-2 immunoassay in 9575 samples from blood donors (n = 6714) and diagnostic specimens (n = 2861) were 99.82% (95% CI 99.69-99.91) and 99.93% (95% CI 99.75-99.99), respectively. Among 2256 samples from pregnant women, specificity was 99.91% (95% CI 99.68-99.99). Among 205 paediatric samples, specificity was 100% (95% CI 98.22-100). ConclusionThe Elecsys Anti-SARS-CoV-2 immunoassay demonstrated a very high specificity across blood donor samples and diagnostic specimens from Germany, Austria and Switzerland. Our findings support the use of the Elecsys Anti-SARS-CoV-2 immunoassay as a potential tool for determination of an immune response following previous exposure to SARS-CoV-2 in the general population, including in blood donors, pregnant women and paediatric populations.

BackgroundLittle is known about the performance of the Roche novel severe acute respiratory syndrome coronavirus 2 antibody (anti-SARS-CoV-2) assay. We provide an extensive evaluation of this fully automated assay on the Cobas e801/e602 immunoassay analysers. MethodsWe assessed the linearity, precision, and throughput of the Roche anti-SARS-CoV-2 assay. Sensitivity was calculated from 349 SARS-CoV-2 polymerase chain reaction (PCR) positive samples; specificity was determined from 714 coronavirus disease 2019 (COVID-19)-naive samples. We examined cross-reactivity against other antibody positive samples (syphilis, RF, ANA, ds-DNA, influenza, dengue, HBV, HCV) and the anti-SARS-CoV-2 kinetics. ResultsThe assay cut-off index (COI) was linear up to 90.7. The inter-assay precision was 2.9% for a negative control (COI=0.1) and 5.1% for a positive control (COI=3.0). Assay time is 18min and results are available 1 minute later; throughput for 300 samples was 76 minutes. No cross-reactivity was observed with other antibody positive samples; specificity was 100%. The assay has a sensitivity of 97.1% 14 days after PCR positivity (POS) and 100% at [&ge;]21 days POS; 48.2% of cases had anti-SARS-CoV-2 within 6 days POS. In 11 subjects in whom serum was available prior to a positive antibody signal (COI [&ge;]1.0) the interval between the last negative and first positive COI (time to "sero-conversion") on average is 3 days (range 1-6 days) and 4 more days (range 1-7) for the anti-SARS-CoV-2 to plateau. ConclusionThe Roche anti-SARS-CoV-2 assay shows excellent performance with minimal cross-reactivity from other viral and confounding antibodies. Antibody development and sero-conversion appears quite early.

BackgroundInfection of backyard and poultry with low pathogenicity avian influenza LPAI A(H5N2) viruses has occurred in Mexico since 1994, and the first human infection caused by this influenza virus was detected in 2024. Since its emergence in the Americas, frequent reassortments between high pathogenicity avian influenza HPAI A(H5N1) and LPAI viruses has occurred. In September 2025, the Instituto Nacional de Enfermedades Respiratorias of Mexico City identified an unsubtypeable influenza A virus infection in a young adult patient later determined to be a reassortant HPAI (H5N2) virus with a clade 2.3.4.4b HA. MethodsWe analyzed clinical and epidemiologic data from this patient. Respiratory samples were tested for influenza RT-qPCR assays. Genomic sequence and phylogenetics analyses were performed to provisionally assign a new genotype to the novel HPAI A(H5N2) reassortant virus. ResultsThe patient presented with fever and tachypnea, later developed hemoptysis and thoracic pain, with oxygen saturation decreasing to 70%. CT scan showed bilateral ground-glass opacities consistent with diffuse alveolar hemorrhage and zones consistent with consolidation. Clinical improvement was observed and the patient was discharged. Through viral complete genome analysis, we identified an HPAI A(H5N2) virus with genes from both clade 2.3.4.4b A(H5N1) viruses similar to those detected in North America during 2022-2023 and genes from the LPAI A(H5N2) viruses detected in Mexico during 2024. ConclusionsThis is the first ever laboratory-confirmed human infection caused by an HPAI A(H5N2) virus infection, suggesting a new genotype provisionally classified as B3.14. The relationship of the virus with the severity of illness remains unknown.