Serological Testing
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2021 ◽  
Vol 3 (10) ◽  
Girish Chandra Dash ◽  
Debaprasad Parai ◽  
Hari Ram Choudhary ◽  
Annalisha Peter ◽  
Usha Kiran Rout ◽  

Introduction. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody responses remain poorly understood and the clinical utility of serological testing is still unclear. Aim. To understand the relationship between the antibody response to SARS-CoV-2 infection and the demographics and cycle threshold (C t) values of confirmed RT-PCR patients. Methodology. A total of 384 serum samples were collected from individuals between 4–6 weeks after confirmed SARS-CoV-2 infection and tested for the development of immunoglobulin class G (IgG) against SARS-CoV-2. The C t values, age, gender and symptoms of the patients were correlated with the development of antibodies. Results. IgG positivity was found to be 80.2 % (95 % CI, 76.2–84.2). Positivity increased with a decrease in the C t value, with the highest (87.6 %) positivity observed in individuals with C t values <20. The mean (±sd) C t values for IgG positives and negatives were 23.34 (±6.09) and 26.72 (±7.031), respectively. No significant difference was found for demographic characteristics such as age and sex and symptoms and antibody response. The current study is the first of its kind wherein we have assessed the correlation of the RT-PCR C t with the development of IgG against SARS-CoV-2. Conclusion. Although C t values might not have any relation with the development of symptoms, they are associated with the antibody response among SARS-CoV-2-infected individuals.

Giuseppe Lippi ◽  
Gian Luca Salvagno ◽  
Brandon Michael Henry ◽  
Laura Pighi ◽  
Simone De Nitto

Background: This study aimed at monitoring the kinetics of serum total anti-SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) antibodies in a cohort of healthcare workers after voluntary vaccination with Pfizer-BioNTech coronavirus disease 2019 (COVID-19).Methods: The study population consisted of 787 healthcare workers (mean age 44±12 years; 66% females), who received two 30 μg doses of Pfizer-BioNTech COVID-19 vaccine, 3 weeks apart. Venous blood was drawn before the first vaccine dose, immediately before the second vaccine dose, and then at 1, 3 and 6 months after the second vaccine dose. Serological testing employed the total anti-SARS-CoV-2 antibodies measurement with Roche Elecsys Anti-SARS-CoV-2 S chemiluminescent immunoassay.Results: The median serum levels of total anti-SARS-CoV-2 antibodies reached the peak (1762 KU/L) 1 month after the second vaccine dose, but tended to progressively decline at the 3-month (1086 KU/L) and 6-month (802 KU/L) follow-up points. Overall, the values after 3- and 6-months were 37% and 57% lower than the corresponding concentrations measured at the peak. No healthcare worker had total anti-SARS-CoV-2 antibodies below the method-dependent cut-off. The decline compared to the peak was more accentuated in baseline seropositive persons than in those who were baseline seronegative (74% vs. 52%) cohort. The 6-month post-vaccination anti-SARS-CoV-2 antibodies in subjects aged <65 years remained over 2-fold higher than that measured in those aged ≥65 years (813 vs. 343 KU/L). Conclusions: Gradual decline of total anti-SARS-CoV-2 antibodies occurred 6 months after Pfizer-BioNTech COVID-19 vaccination, though values remained higher than the method-dependent cut-off, with no case of seronegativization.

2021 ◽  
Daniel M. Williams ◽  
Hayley Hornsby ◽  
Ola M. Shehata ◽  
Rebecca Brown ◽  
Domen Zafred ◽  

The strong humoral immune response produced against the SARS-CoV-2 nucleocapsid (N) and spike (S) proteins has underpinned serological testing but the prevalence of antibody responses to other SARS-CoV-2 proteins, which may be of use as further serological markers, is still unclear. Cell-based serological screening platforms can fulfil a crucial niche in the identification of antibodies which recognise more complex folded epitopes or those incorporating post-translation modifications which may be undetectable by other methods used to investigate the antigenicity of the SARS-CoV-2 proteome. Here, we employed automated high content immunofluorescence microscopy (AHCIM) to assess the viability of such an approach as a method capable of assaying humoral immune responses against full length SARS-CoV-2 proteins in their native cellular state. We first demonstrate that AHCIM provides high sensitivity and specificity in the detection of SARS-CoV-2 N and S IgG. Assessing the prevalence of antibody responses to the SARS-CoV-2 structural membrane protein (M), we further find that 85% of COVID-19 patients within our sample set developed detectable M IgG responses (M sensitivity 85%, N sensitivity 93%, combined N + M sensitivity 95%). The identification of M as a serological marker of high prevalence may be of value in detecting additional COVID-19 cases during the era of mass SARS-CoV-2 vaccinations, where serological screening for SARS CoV-2 infections in vaccinated individuals is dependent on detection of antibodies against N. These findings highlight the advantages of using cell-based systems as serological screening platforms and raise the possibility of using M as a widespread serological marker alongside N and S.

Wil Lieberman-Cribbin ◽  
Marta Galanti ◽  
Jeffrey Shaman

Abstract Background We characterized SARS-CoV-2 antibody test prevalence and positive test prevalence across New York City (NYC) in order to investigate disparities in testing outcomes by race and socioeconomic status (SES). Methods Serologic data were downloaded from the NYC Coronavirus data repository (August 2020–December 2020). Area-level characteristics for NYC neighborhoods were downloaded from U.S. census data and a socioeconomic vulnerability index was created. Spatial generalized linear mixed models were performed to examine the association between SES and antibody testing and positivity. Results The proportion of Hispanic population (Posterior Median: 0.001, 95% Credible Interval: 0.0003-0.002), healthcare workers (0.003, 0.0001-0.006), essential workers (0.003, 0.001-0.005), age ≥ 65 years (0.003, 0.00002-0.006), and high SES (SES quartile 3 vs 1: 0.034, 0.003-0.062) were positively associated with antibody tests per 100,000 residents. The White proportion (-0.002, -0.003- -0.001), SES index (quartile 3 vs 1: -0.068, -0.115- -0.017; quartile 4 vs 1: -0.077- -0.134, -0.018) and age ≥ 65 years (-0.005, -0.009- -0.002) were inversely associated with positivity, whereas the Hispanic (0.004, 0.002-0.006), and essential worker proportions (0.008, 0.003-0.012) had positive coefficients. Conclusions Disparities in serologic testing and seropositivity exist on socioeconomic status and race/ethnicity across NYC, indicative of excess COVID-19 burden in vulnerable and marginalized populations.

Parham Sendi ◽  
Rossella Baldan ◽  
Marc Thierstein ◽  
Nadja Widmer ◽  
Peter Gowland ◽  

Abstract Background Protests and police fieldwork provides a high exposure environment for SARS-CoV-2 infections. In this cross-sectional analysis, we investigated the seroprevalence among a police cohort, and sociodemographic, work and health-related factors associated with seropositivity. Methods Study participants were invited for serological testing of SARS-CoV-2 and to complete online questionnaires. Serum neutralization titres towards the wild-type SARS-CoV-2 spike protein (expressing D614G) and the alpha and beta variants were measured in seropositive study participants. Results 978 police personnel representing 35% of the entire staff participated from February to March 2021. The seroprevalence was 12.9%. It varied by geographic region within the canton; ranged from 9% to 13.5% in three regions, including the city; and was 22% in Bernese Seeland/Jura with higher odds for seropositivity (OR 2.38, 95% CI 1.28–4.44, P=0.006). Job roles with mainly office activity were associated with a lower risk of seropositivity (0.33, 0.14–0.77, P=0.010). Most seropositive employees (67.5%) reported having had COVID-19 three months or longer prior to serological testing. Selfreported compliance with mask wearing during working hours was 100%; 45% of all seropositive versus 5% of all seronegative participants (P&lt;0.001) reported having had contact with a proven COVID-19 case living in the same household prior to serological testing. The level of serum antibody titres correlated with neutralization capacity. Antibodies derived from natural SARS-CoV-2 infection effectively neutralized the SARS-CoV-2 spike protein, but were less effective against the alpha and beta variants. Conclusions The seroprevalence of anti-SARS-CoV-2 antibodies of police officers was comparable to that reported in the general population, suggesting that the personal protective equipment of the police is effective, and that household contacts are the leading transmission venues. The level of serum antibody titres, in particular that of anti-spike antibodies, correlated well with neutralization capacity. Low antibody titres acquired from natural infection were not effective against variants.

2021 ◽  
Vol 14 (1) ◽  
Marie Edvinsson ◽  
Camilla Norlander ◽  
Kenneth Nilsson ◽  
Andreas Mårtensson ◽  
Elisabet Skoog ◽  

Abstract Background Bartonella spp. are emerging pathogens transmitted by arthropod vectors, possibly including ticks. We have investigated signs of bartonellosis in Swedish patients with presumed tick-bite exposure and symptom duration of at least 6 months. Methods Serological testing for Bartonella henselae and Bartonella quintana was performed in 224 patients. Symptoms, tick exposure, evidence of co-infection and previous treatments were evaluated. Seropositive patients were compared to a matched group (twofold larger and negative serology) from the same study cohort. Results Seroprevalence was 7% for B. henselae and 1% for B. quintana, with one patient testing positive to both agents. Tick bites were reported by 63% of the patients in the seropositive group and 88% in the seronegative group and presumed tick exposure was more common in the seronegative group. Animal contact was equally common in both groups, along with reported symptoms. The most common symptoms were fatigue, muscular symptoms, arthralgia and cognitive symptoms. Exposure to co-infections was evenly distributed in the seropositive and seronegative groups. Conclusions Antibodies to Bartonella were more common in this cohort of patients than in cohorts of healthy Swedish blood donors in previous studies but lower than those in blood donors from southern Europe. Positive Bartonella serology was not linked to any specific symptom, nor to (suspected) tick-bite exposure. Graphical abstract

2021 ◽  
Vol 42 (2) ◽  
pp. 95-101
Lidija Kareva ◽  
Katarina Stavrik ◽  
Kristina Mironska ◽  
Arjeta Hasani ◽  
Sonja Bojadzieva ◽  

Abstract Multisystem Inflammatory Syndrome in Children (MIS-C) is characterized by an inflammation with fever, elevated inflammatory markers, conjunctivitis, rash, impaired coagulation, gastrointestinal symptoms and cardiac abnormalities that may progress to multiorgan failure. The presence of a positive COVID-19 antigen via a PCR test, serological testing for antibodies or close contact with a person diagnosed with COVID-19 helps differentiate MIS-C from other diseases. Gastrointestinal symptoms are recognized to be associated with COVID-19 infection or MIS-C in children, presenting as abdominal pain, gastrointestinal infection with watery stools, appendicitis, ileitis, pancreatitis and hepatitis, confusing the diagnosis with other gastrointestinal diseases. In this case report, we describe an 11 year old boy with MIS-C, who presents acute phlegmona of the appendix for which he undergoes appendectomy, accompanied with acute pancreatitis. These manifestations of MIS-C in our patient resolved without additional complications after a 2 month follow up. We call attention to MIS-C presenting in pediatric patients with fever and abdominal pain which might be caused by appendicitis and pancreatitis, and we recommend abdominal imaging and additional laboratory investigation to promote earlier diagnosis.

2021 ◽  
Vol 7 (3) ◽  
pp. 100
Isa Ansori ◽  
Soraya Riefani ◽  
Ira Nurrasyidah

Introduction: Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is the cause of clinical disease, better known as COVID-19. The most common method to detect COVID-19 is serological testing of IgM and IgG in response to viral infections using rapid diagnostic test (RDT). Several other guidelines consider polymerase chain reaction (PCR) as the gold standard for diagnosis becausePCR has high sensitivity and specificity values in detecting SARS-CoV-2.Methods: This was a descriptive analytical study. The samples were taken from medical records of COVID-19 patients in Ulin General Hospital Banjarmasin from March to October 2020. Statistical Package for the Social Sciences (SPSS) 16.0 software and Chi-Square test were used for data analysis.Results: From 751 COVID-19 patients, 408 patients (54.32%) had rapid antibody with positive PCR, 132 patients (17.57%) had reactive rapid antibody with negative PCR, 152 patients (20.23%) had non-reactive rapid antibody with positive PCR, and 59 patients (7.85%) had non-reactive rapid antibody with negative PCR. The rapid antibody had sensitivity of 72.85% and specificity of 30.89%. From Chi-Square test, reactive rapid antibody was not correlated with PCR positive results; values of p = 0.320, odds ratio (OR) 1.20.Conclusion: The rapid test antibody could not be recommended as a diagnostic tool. In this study, it was also found that there was no relationship between reactive rapid test results and positive SARS-CoV PCR.

F. Sneha Kukanur ◽  
G. Naveen ◽  
N. Ashwin Chitrabanu ◽  
B.M. Prashant ◽  
R. Meghana ◽  

Dengue viral infection is the most widely spread arbo-viral disease in Indian subcontinent. High index of clinical suspicion especially during its peak season can be rewarding in diagnosing as well as early case management of anticipated DHF and DSS cases. To estimate the magnitude, seasonal-variation, serological as well as hematological aspects of dengue cases. This was a prospective observational study held in Microbiology and Hematology laboratories of our hospital for duration of one year from July-2019 to June-2020. All the suspected dengue cases were subjected to NS1-antigen, IgM and IgG antibody detection. The samples were also tested for platelet count, total count, haematocrit as well as hemoglobin estimation. All 1,550 dengue suspected cases were subjected to serological testing, among which 157 (10.1%) were positive. The most affected populations were the adult male. As the study was conducted for one year, we could observe the seasonal trend which peaked during post-monsoon. Out of 157 cases, 81.5%, 0.6% and 17.8% were determined as primary, secondary and old dengue cases respectively. There was a significant association between NS1 antigen and fever of </= 5 days duration with ‘p’ value< 0.00001. Thrombocytopenia, leucopenia and increased haematocrit were witnessed in 15.9%, 28.6% and 35% respectively. Our study shows that we had a high magnitude of primary cases that are prone to secondary dengue infection which might have a catastrophic effect giving rise to DHF, DSS or SD.

2021 ◽  
Vol 10 (19) ◽  
pp. 4341
Zhangchen Zhao ◽  
Stephen Salerno ◽  
Xu Shi ◽  
Seunggeun Lee ◽  
Bhramar Mukherjee ◽  

Testing for SARS-CoV-2 antibodies is commonly used to determine prior COVID-19 infections and to gauge levels of infection- or vaccine-induced immunity. Michigan Medicine, a primary regional health center, provided an ideal setting to understand serologic testing patterns over time. Between 27 April 2020 and 3 May 2021, characteristics for 10,416 individuals presenting for SARS-CoV-2 antibody tests (10,932 tests in total) were collected. Relative to the COVID-19 vaccine roll-out date, 14 December 2020, the data were split into a pre- (8026 individuals) and post-vaccine launch (2587 individuals) period and contrasted with untested individuals to identify factors associated with tested individuals and seropositivity. Exploratory analysis of vaccine-mediated seropositivity was performed in 347 fully vaccinated individuals. Predictors of tested individuals included age, sex, smoking, neighborhood variables, and pre-existing conditions. Seropositivity in the pre-vaccine launch period was 9.2% and increased to 46.7% in the post-vaccine launch period. In the pre-vaccine launch period, seropositivity was significantly associated with age (10 year; OR = 0.80 (0.73, 0.89)), ever-smoker status (0.49 (0.35, 0.67)), respiratory disease (4.38 (3.13, 6.12)), circulatory disease (2.09 (1.48, 2.96)), liver disease (2.06 (1.11, 3.84)), non-Hispanic Black race/ethnicity (2.18 (1.33, 3.58)), and population density (1.10 (1.03, 1.18)). Except for the latter two, these associations remained statistically significant in the post-vaccine launch period. The positivity rate of fully vaccinated individual was 296/347(85.3% (81.0%, 88.8%)).

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