High-Throughput Multiplex SARS-CoV-2 IgG Microsphere Immunoassay for Dried Blood Spots: A Public Health Strategy for Enhanced Serosurvey Capacity

Use of dried blood spots in the detection of coronavirus disease 2019 (COVID-19): A systematic review

INTRODUCTION

COVID-19 disease continues to be a global health concern. The current protocol for detecting SARS-CoV-2 requires healthcare professionals to draw blood from patients. Recent studies showed that dried blood spot (DBS) is a valuable sampling procedure that can collect a low blood volume without the need for the presence of medical practitioners. This study synthesized the available literature on using DBS as a blood collection tool to diagnose COVID-19 disease.

MATERIALS AND METHODS

A comprehensive search utilizing OVID, CINAHL, and Scopus databases was done from inception to March 2023. Five reviewers collected, extracted and organized the study data.

RESULTS

This systematic review included 57 articles. DBS was commonly prepared by finger pricking. Most studies showed more favorable results and longer sample stability (more than 1080 days) with lower storage temperature conditions for the DBS. DBS samples were mostly used for serological assays for COVID-19 disease detection. ELISA was the most used detection method (43.66 %). Diagnostic performance of laboratory tests for COVID-19 using DBS sample showed high sensitivity of up to 100 % for immunoassay tests and 100 % specificity in agglutination, PCR, and DELFIA assays.

CONCLUSION

DBS sampling coupled with serological testing can be an alternative method for collecting blood and detecting COVID-19 disease. These tests using DBS samples showed excellent diagnostic performance across various geographic locations and demographics.

Quantitating SARS-CoV-2 Neutralizing Antibodies from Human Dried Blood Spots

Background

In the earliest days of COVID-19 pandemic, the collection of dried blood spots (DBS) enabled public health laboratories to undertake population-scale seroprevalence studies to estimate rates of SARS-CoV-2 exposure. With SARS-CoV-2 seropositivity levels now estimated to exceed 94% in the United States, attention has turned to using DBS to assess functional (neutralizing) antibodies within cohorts of interest.

Methods

Contrived DBS eluates from convalescent, fully vaccinated and pre-COVID-19 serum samples were evaluated in SARS-CoV-2 plaque reduction neutralization titer (PRNT) assays, a SARS-CoV-2 specific 8-plex microsphere immunoassay, a cell-based pseudovirus assay, and two different spike-ACE2 inhibition assays, an in-house Luminex-based RBD-ACE2 inhibition assay and a commercial real-time PCR-based inhibition assay (NAB-Sure™).

Results

DBS eluates from convalescent individuals were compatible with the spike-ACE2 inhibition assays, but not cell-based pseudovirus assays or PRNT. However, the insensitivity of cell-based pseudovirus assays was overcome with DBS eluates from vaccinated individuals with high SARS-CoV-2 antibody titers.

Conclusion

SARS-CoV-2 neutralizing titers can be derived with confidence from DBS eluates, thereby opening the door to the use of these biospecimens for the analysis of vulnerable populations and normally hard to reach communities.

Demographic and Clinical Factors Associated With SARS-CoV-2 Spike 1 Antibody Response Among Vaccinated US Adults: the C4R Study

This study investigates correlates of anti-S1 antibody response following COVID-19 vaccination in a U.S. population-based meta-cohort of adults participating in longstanding NIH-funded cohort studies. Anti-S1 antibodies were measured from dried blood spots collected between February 2021-August 2022 using Luminex-based microsphere immunoassays. Of 6245 participants, mean age was 73 years (range, 21-100), 58% were female, and 76% were non-Hispanic White. Nearly 52% of participants received the BNT162b2 vaccine and 48% received the mRNA-1273 vaccine. Lower anti-S1 antibody levels are associated with age of 65 years or older, male sex, higher body mass index, smoking, diabetes, COPD and receipt of BNT16b2 vaccine (vs mRNA-1273). Participants with a prior infection, particularly those with a history of hospitalized illness, have higher anti-S1 antibody levels. These results suggest that adults with certain socio-demographic and clinical characteristics may have less robust antibody responses to COVID-19 vaccination and could be prioritized for more frequent re-vaccination.

A bead-based multiplex assay covering all coronaviruses pathogenic for humans for sensitive and specific surveillance of SARS-CoV-2 humoral immunity

Serological assays measuring antibodies against SARS-CoV-2 are key to describe the epidemiology, pathobiology or induction of immunity after infection or vaccination. Of those, multiplex assays targeting multiple antigens are especially helpful as closely related coronaviruses or other antigens can be analysed simultaneously from small sample volumes, hereby shedding light on patterns in the immune response that would otherwise remain undetected. We established a bead-based 17-plex assay detecting antibodies targeting antigens from all coronaviruses pathogenic for humans: SARS-CoV-2, SARS-CoV, MERS-CoV, HCoV strains 229E, OC43, HKU1, and NL63. The assay was validated against five commercial serological immunoassays, a commercial surrogate virus neutralisation test, and a virus neutralisation assay, all targeting SARS-CoV-2. It was found to be highly versatile as shown by antibody detection from both serum and dried blot spots and as shown in three case studies. First, we followed seroconversion for all four endemic HCoV strains and SARS-CoV-2 in an outbreak study in day-care centres for children. Second, we were able to link a more severe clinical course to a stronger IgG response with this 17-plex-assay, which was IgG1 and IgG3 dominated. Finally, our assay was able to discriminate recent from previous SARS-CoV-2 infections by calculating the IgG/IgM ratio on the N antigen targeting antibodies. In conclusion, due to the comprehensive method comparison, thorough validation, and the proven versatility, our multiplex assay is a valuable tool for studies on coronavirus serology.

Development of a novel serological assay for the detection of mpox infection in vaccinated populations

In 2022 the World Health Organization declared a Public Health Emergency for an outbreak of mpox, the zoonotic Orthopoxvirus (OPV) affecting at least 104 nonendemic locations worldwide. Serologic detection of mpox infection is problematic, however, due to considerable antigenic and serologic cross-reactivity among OPVs and smallpox-vaccinated individuals. In this report, we developed a high-throughput multiplex microsphere immunoassay using a combination of mpox-specific peptides and cross-reactive OPV proteins that results in the specific serologic detection of mpox infection with 93% sensitivity and 98% specificity. The New York State Non-Vaccinia Orthopoxvirus Microsphere Immunoassay is an important tool to detect subclinical mpox infection and understand the extent of mpox spread in the community through retrospective analysis.

Quantifying neutralising antibody responses against SARS-CoV-2 in dried blood spots (DBS) and paired sera

The ongoing SARS-CoV-2 pandemic was initially managed by non-pharmaceutical interventions such as diagnostic testing, isolation of positive cases, physical distancing and lockdowns. The advent of vaccines has provided crucial protection against SARS-CoV-2. Neutralising antibody (nAb) responses are a key correlate of protection, and therefore measuring nAb responses is essential for monitoring vaccine efficacy. Fingerstick dried blood spots (DBS) are ideal for use in large-scale sero-surveillance because they are inexpensive, offer the option of self-collection and can be transported and stored at ambient temperatures. Such advantages also make DBS appealing to use in resource-limited settings and in potential future pandemics. In this study, nAb responses in sera, venous blood and fingerstick blood stored on filter paper were measured. Samples were collected from SARS-CoV-2 acutely infected individuals, SARS-CoV-2 convalescent individuals and SARS-CoV-2 vaccinated individuals. Good agreement was observed between the nAb responses measured in eluted DBS and paired sera. Stability of nAb responses was also observed in sera stored on filter paper at room temperature for 28 days. Overall, this study provides support for the use of filter paper as a viable sample collection method to study nAb responses.

Development of a Novel Serological Assay for the Detection of Mpox Infection in Vaccinated Populations

In 2022 the World Health Organization declared a Public Health Emergency for an outbreak of mpox, the zoonotic Orthopoxvirus (OPV) affecting at least 103 non-endemic locations world-wide. Serologic detection of mpox infection is problematic, however, due to considerable antigenic and serologic cross-reactivity among OPVs and smallpox-vaccinated individuals. In this report, we developed a high-throughput multiplex microsphere immunoassay (MIA) using a combination of mpox-specific peptides and cross-reactive OPV proteins that results in the specific serologic detection of mpox infection with 93% sensitivity and 98% specificity. The New York State Non-Vaccinia Orthopoxvirus Microsphere Immunoassay is an important diagnostic tool to detect subclinical mpox infection and understand the extent of mpox spread in the community through retrospective analysis.

Development of a Method for Detection of SARS-CoV-2 Nucleocapsid Antibodies on Dried Blood Spot by DELFIA Immunoassay

Antibodies against the SARS-CoV-2 nucleocapsid protein are produced by the immune system in response to SARS-CoV-2 infection, but most available vaccines developed to fight the pandemic spread target the SARS-CoV-2 spike protein. The aim of this study was to improve the detection of antibodies against the SARS-CoV-2 nucleocapsid by providing a simple and robust method applicable to a large population. For this purpose, we developed a DELFIA immunoassay on dried blood spots (DBSs) by converting a commercially available IVD ELISA assay. A total of forty-seven paired plasma and dried blood spots were collected from vaccinated and/or previously SARS-CoV-2-infected subjects. The DBS-DELFIA resulted in a wider dynamic range and higher sensitivity for detecting antibodies against the SARS-CoV-2 nucleocapsid. Moreover, the DBS-DELFIA showed a good total intra-assay coefficient of variability of 14.6%. Finally, a strong correlation was found between SARS-CoV-2 nucleocapsid antibodies detected by the DBS-DELFIA and ELISA immunoassays (r = 0.9). Therefore, the association of dried blood sampling with DELFIA technology may provide an easier, minimally invasive, and accurate measurement of SARS-CoV-2 nucleocapsid antibodies in previously SARS-CoV-2-infected subjects. In conclusion, these results justify further research to develop a certified IVD DBS-DELFIA assay for detecting SARS-CoV-2 nucleocapsid antibodies useful for diagnostics as well as for serosurveillance studies.

Use of Self-Collected Dried Blood Spots and a Multiplex Microsphere Immunoassay to Measure IgG Antibody Response to COVID-19 Vaccines

Serosurveys can determine the extent and spread of a pathogen in populations. However, collection of venous blood requires trained medical staff. Dried blood spots (DBS) are a suitable alternative because they can be self-collected and stored/shipped at room temperature. As COVID-19 vaccine deployment began in early 2021, we rapidly enrolled laboratory employees in a study to evaluate IgG antibody levels following vaccination. Participants received a DBS collection kit, self-collection instructions, and a brief questionnaire. Three DBS were collected by each of 168 participants pre- and/or postvaccination and tested with a multiplex microsphere immunoassay (MIA) that separately measures IgG antibodies to SARS-CoV-2 spike-S1 and nucleocapsid antigens. Most DBS (99.6%, 507/509) were suitable for testing. Participants with prior SARS-CoV-2 infection (n = 7) generated high S antibody levels after the first vaccine dose. Naïve individuals (n = 161) attained high S antibody levels after the second dose. Similar antibody levels were seen among those vaccinated with Moderna (n = 29) and Pfizer-BioNTech (n = 137). For those receiving either mRNA vaccine, local side effects were more common after the first vaccine dose, whereas systemic side effects were more common after the second dose. Individuals with the highest antibody levels in the week prior to the second vaccine dose experienced more side effects from the second dose. Our study demonstrated that combining self-collected DBS and a multiplex MIA is a convenient and effective way to assess antibody levels to vaccination and could easily be used for population serosurveys of SARS-CoV-2 or other emerging pathogens. IMPORTANCE Serosurveys are an essential tool for assessing immunity in a population (1, 2). However, common barriers to effective serosurveys, particularly during a pandemic, include high-costs, resources required to collect venous blood samples, lack of trained laboratory technicians, and time required to perform the assay. By utilizing self-collected dried blood spots (DBS) and our previously developed high-throughput microsphere immunoassay, we were able to significantly reduce many of these common challenges. Participants were asked to self-collect three DBS before and/or after they received their COVID-19 vaccines to measure antibody levels following vaccination. Participants successfully collected 507 DBS that were tested for IgG antibodies to the spike and nucleocapsid proteins of SARS-CoV-2. When used with self-collected DBS, our relatively low-cost assay significantly reduced common barriers to collecting serological data from a population and was able to effectively assess antibody response to vaccination.

Coronavirus Antibody Responses before COVID-19 Pandemic, Africa and Thailand

Prior immune responses to coronaviruses might affect human SARS-CoV-2 response. We screened 2,565 serum and plasma samples collected from 2013 through early 2020, before the COVID-19 pandemic began, from 2,250 persons in 4 countries in Africa (Kenya, Nigeria, Tanzania, and Uganda) and in Thailand, including persons living with HIV-1. We detected IgG responses to SARS-CoV-2 spike (S) subunit 2 protein in 1.8% of participants. Profiling against 23 coronavirus antigens revealed that responses to S, subunit 2, or subunit 1 proteins were significantly more frequent than responses to the receptor-binding domain, S-Trimer, or nucleocapsid proteins (p<0.0001). We observed similar responses in persons with or without HIV-1. Among all coronavirus antigens tested, SARS-CoV-2, SARS-CoV-1, and Middle East respiratory syndrome coronavirus antibody responses were much higher in participants from Africa than in participants from Thailand (p<0.01). We noted less pronounced differences for endemic coronaviruses. Serosurveys could affect vaccine and monoclonal antibody distribution across global populations.

Association of Symptoms After COVID-19 Vaccination With Anti-SARS-CoV-2 Antibody Response in the Framingham Heart Study

This cohort study examines the association of self-reported postvaccination symptoms with anti–SARS-CoV-2 antibody response among Framingham Heart Study participants contributing to the Collaborative Cohort of Cohorts for COVID-19 Research study.

Utility of Newborn Dried Blood Spots to Ascertain Seroprevalence of SARS-CoV-2 Antibodies Among Individuals Giving Birth in New York State, November 2019 to November 2021

IMPORTANCE

Serosurveys can be used to monitor population-level dynamics of COVID-19 and vaccination. Dried blood spots (DBSs) collected from infants contain maternal IgG antibodies and are useful for serosurveys of individuals recently giving birth.

OBJECTIVES

To examine SARS-CoV-2 antibody prevalence in pregnant individuals in New York State, identify associations between SARS-CoV-2 antibody status and maternal and infant characteristics, and detect COVID-19 vaccination among this population.

DESIGN, SETTING, AND PARTICIPANTS

A population-based, repeated cross-sectional study was conducted to detect SARS-CoV-2 nucleocapsid (N) and spike (S) IgG antibodies. Deidentified DBS samples and data submitted to the New York State Newborn Screening Program between November 1, 2019, and November 30, 2021, were analyzed.

EXPOSURES

Prenatal exposure to SARS-CoV-2 antibodies.

MAIN OUTCOMES AND MEASURES

The presence of IgG antibodies to SARS-CoV-2 N and S antigens was measured using a microsphere immunoassay. Data were analyzed by geographic region and compared with reported COVID-19 cases and vaccinations among reproductive-aged females (15-44 years of age). Data were stratified by infant birth weight, gestational age, maternal age, and multiple birth status.

RESULTS

Dried blood spot samples from 415 293 infants (median [IQR] age, 1.04 [1.00-1.20] days; 210 805 [51.1%] male) were analyzed for SARS-CoV-2 antibodies. The first known antibody-positive infant in New York State was born on March 29, 2020. SARS-CoV-2 seroprevalence reflected statewide and regional COVID-19 cases among reproductive-aged females in the prevaccine period. From February through November 2021, S seroprevalence was strongly correlated with cumulative vaccinations in each New York State region and in the state overall (rs = 0.92-1.00, P ≤ .001). S and N seroprevalences were significantly lower in newborns with very low birth weight (720 [14.8%] for S and 138 [2.8%] for N, P < .001) and low birth weight (5160 [19.3%] for S and 1233 [4.6%] for N, P = .009) compared with newborns with normal birth weight (77 116 [20.1%] for S and 19 872 [5.2%] for N). Lower N and higher S seroprevalences were observed in multiple births (odds ratio [OR], 0.84; 95% CI, 0.75-0.94; P = .002 for N and OR, 1.24; 95% CI, 1.18-1.31; P < .001 for S) vs single births and for maternal age older than 30 years (OR, 0.87; 95% CI, 0.80-0.94; P < .001 for N and OR, 1.17; 95% CI, 1.11-1.23; P < .001 for S) vs younger than 20 years.

CONCLUSIONS AND RELEVANCE

In this study, seroprevalence in newborn DBS samples reflected COVID-19 case fluctuations and vaccinations among reproductive-aged women during the study period. These results demonstrate the utility of using newborn DBS testing to estimate SARS-CoV-2 seroprevalence in pregnant individuals.

Evaluation of serological assays for SARS-CoV-2 antibody testing from dried blood spots collected from cohorts with prior SARS-CoV-2 infection

Background

Dried blood spot (DBS) specimens are a useful serosurveillance tool particularly in hard-to-reach populations but their application for detecting SARS-CoV-2 infection is poorly characterised.

Objectives

To compare detection of naturally acquired SARS-CoV-2 antibodies in paired DBS and serum specimens using commercially available serological immunoassays.

Study Design

Specimens were collected through St Vincent's Hospital observational post COVID-19 cohort study (ADAPT). Laboratory spotted DBS from venepuncture were initially tested on seven assays, a DBS validation completed on three with clinically collected fingerstick DBSs tested on one.

Results

Sensitivity for Euroimmun nucleocapsid (NCP) IgG ELISA from laboratory spotted DBS (n=145), Euroimmun spike, IgG ELISA from laboratory spotted DBS (n=161), and Binding Site total antibody ELISA from clinically collected fingerstick DBS (n=391) was 100% (95% CI: 95.8-100%), 100% (95% CI: 95.8-100%) and 92.9% (95% CI: 89.5-95.5%), respectively. Specificity was 66.2% (95% CI: 53.6-77.0%), 96% (95% CI: 88.7-99.1%) and 98.8% (95% CI: 93.3-99.9%), respectively. All three assays’ results displayed a strong positive correlation between DBS compared to paired serum.

Conclusions

The Binding Site™ spike total antibody and Euroimmun™ spike IgG ELISAs provided good analytical performance, demonstrating that DBS specimens could facilitate specimen collection in the epidemiological surveillance of SARS-CoV-2 infection. This is highly applicable in populations and settings where venepuncture is problematic (including community based regional/remote settings, nursing homes, prisons, and schools).

The Serological Sciences Network (SeroNet) for COVID-19: Depth and Breadth of Serology Assays and Plans for Assay Harmonization

In October 2020, the National Cancer Institute (NCI) Serological Sciences Network (SeroNet) was established to study the immune response to COVID-19, and “to develop, validate, improve, and implement serological testing and associated technologies” (https://www.cancer.gov/research/key-initiatives/covid-19/coronavirus-research-initiatives/serological-sciences-network). SeroNet is comprised of 25 participating research institutions partnering with the Frederick National Laboratory for Cancer Research (FNLCR) and the SeroNet Coordinating Center. Since its inception, SeroNet has supported collaborative development and sharing of COVID-19 serological assay procedures and has set forth plans for assay harmonization. To facilitate collaboration and procedure sharing, a detailed survey was sent to collate comprehensive assay details and performance metrics on COVID-19 serological assays within SeroNet. In addition, FNLCR established a protocol to calibrate SeroNet serological assays to reference standards, such as the U.S. severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serology standard reference material and first WHO international standard (IS) for anti-SARS-CoV-2 immunoglobulin (20/136), to facilitate harmonization of assay reporting units and cross-comparison of study data. SeroNet institutions reported development of a total of 27 enzyme-linked immunosorbent assay (ELISA) methods, 13 multiplex assays, and 9 neutralization assays and use of 12 different commercial serological methods. FNLCR developed a standardized protocol for SeroNet institutions to calibrate these diverse serological assays to reference standards. In conclusion, SeroNet institutions have established a diverse array of COVID-19 serological assays to study the immune response to SARS-CoV-2 and vaccines. Calibration of SeroNet serological assays to harmonize results reporting will facilitate future pooled data analyses and study cross-comparisons.

IMPORTANCE SeroNet institutions have developed or implemented 61 diverse COVID-19 serological assays and are collaboratively working to harmonize these assays using reference materials to establish standardized reporting units. This will facilitate clinical interpretation of serology results and cross-comparison of research data.

The Serological Sciences Network (SeroNet) for COVID-19: Depth and Breadth of Serology Assays and Plans for Assay Harmonization

Background

In October 2020, the National Cancer Institute (NCI) Serological Sciences Network (SeroNet) was established to study the immune response to COVID-19, and "to develop, validate, improve, and implement serological testing and associated technologies." SeroNet is comprised of 25 participating research institutions partnering with the Frederick National Laboratory for Cancer Research (FNLCR) and the SeroNet Coordinating Center. Since its inception, SeroNet has supported collaborative development and sharing of COVID-19 serological assay procedures and has set forth plans for assay harmonization.

Methods

To facilitate collaboration and procedure sharing, a detailed survey was sent to collate comprehensive assay details and performance metrics on COVID-19 serological assays within SeroNet. In addition, FNLCR established a protocol to calibrate SeroNet serological assays to reference standards, such as the U.S. SARS-CoV-2 serology standard reference material and First WHO International Standard (IS) for anti-SARS-CoV-2 immunoglobulin (20/136), to facilitate harmonization of assay reporting units and cross-comparison of study data.

Results

SeroNet institutions reported development of a total of 27 ELISA methods, 13 multiplex assays, 9 neutralization assays, and use of 12 different commercial serological methods. FNLCR developed a standardized protocol for SeroNet institutions to calibrate these diverse serological assays to reference standards.

Conclusions

SeroNet institutions have established a diverse array of COVID-19 serological assays to study the immune response to SARS-CoV-2 virus and vaccines. Calibration of SeroNet serological assays to harmonize results reporting will facilitate future pooled data analyses and study cross-comparisons.

Multiplex Technologies in COVID-19 Research, Diagnostics, and Prognostics: Battling the Pandemic

Due to continuous technical developments and new insights into the high complexity of infectious diseases such as COVID-19, there is an increasing need for multiplex biomarkers to aid clinical management and support the development of new drugs and vaccines. COVID-19 disease requires rapid diagnosis and stratification to enable the most appropriate treatment course for the best possible outcomes for patients. In addition, these tests should be rapid, specific, and sensitive. They should rule out other potential causes of illness with simultaneous testing for other diseases. Elevated levels of specific biomarkers can be used to establish severity risks of chronic diseases so that patients can be provided the proper medication at the right time. This review describes the state-of-the-art technologies in proteomics, transcriptomics, and metabolomics, for multiplex biomarker approaches in COVID-19 research.