Dynamics of anti-SARS-CoV-2 antibodies in the Albanian population: Impact of infection- and vaccine-induced immunity during the COVID-19 pandemic.

Objectives: Understanding immune response dynamics during the COVID-19 pandemic is crucial for optimizing future vaccine strategies. This study investigated the infection- and vaccine-induced SARS-CoV-2 antibody responses in the Albanian population from August 2021 to August 2022. Methods: This used a cross-sectional approach, analyzing two independent, randomly selected population samples over 1 year. Participants' demographic, health, vaccination, and COVID-19 data were collected, with blood samples assessed via enzyme linked immunosorbent assay for immunoglobulin G class anti-spike and anti-nucleocapsid antibodies. Results: By August 2022, all individuals receiving one vaccine dose achieved antibody levels comparable to those receiving two doses (median 7.71 index ratio [IR] vs 7.00 IR). In August 2021, those with previous COVID-19 infection receiving one vaccine dose showed median anti-spike immunoglobulin G levels of 7.22 IR compared with 4.84 IR in those without previous infection receiving two doses. However, individuals aged ≥61 years required two vaccine doses to achieve similar immune responses as younger individuals with one dose. Conclusions: These findings underscore the importance of hybrid immunity, suggesting one vaccine dose may suffice for individuals with previous COVID-19 infection, whereas older adults require additional doses for optimal protection. This study provides insights into humoral immune response dynamics, which is crucial for refining COVID-19 vaccination strategies in middle-income countries with low vaccination coverage and high infection rates.

Seroprevalence of SARS-CoV-2 antibodies in children with nephrotic syndrome and chronic kidney disease: a cross-sectional study from India.

BACKGROUND: There is a paucity of literature on the seroprevalence of SARS-CoV-2 antibodies among pediatric patients with underlying kidney disorders; few serosurveys among healthy children have shown seropositivity of 20-65% after different waves of infections. METHODS: The study had a cross-sectional design and was conducted between January 2023 and July 2023; 163 children and adolescents (1-18 years) with nephrotic syndrome and chronic kidney disease (CKD) were screened for Anti-Spike SARS-COV-2 IgG antibodies as detected by a quantitative chemiluminescence immunoassay. Children with nephrotic syndrome, both steroid sensitive (SSNS) and steroid resistant (SRNS) were enrolled during disease remission. Correlation of SARS-CoV-2 seropositivity status was done with age, gender, disease type, treatment duration, immunosuppressants, previous SARS-CoV-2 infection, and immunization status. RESULTS: Of 163 children (63.8% boys) with median age of 9 years; 101 (62%) had underlying nephrotic syndrome (61 SSNS and 40 SRNS), and 62 (38%) children had CKD. Seroprotective titers for SARS-COV2 antibodies were present in 100 (61.3%) children. The median titers for all patients were 37.1 BAU/mL; for nephrotic syndrome they were 27.1 BAU/mL and for CKD they were 76.7 BAU/mL (p = 0.0033). A total of 43 (26.4%) children had high positive antibody levels (> 200 BAU/ml). Among those with nephrotic syndrome 60.7% with SSNS and 43.5% SRNS had seropositive titers. Only 4 (2.5%) children had a history of previous COVID infection and 6 (3.7%) were vaccinated. CONCLUSIONS: In a largely unvaccinated population of children with nephrotic syndrome and CKD, 61.3% were seropositive for SARS-CoV-2 IgG antibody indicating a past asymptomatic infection; titers were significantly higher in CKD compared to nephrotic syndrome.

Unveiling the Quest: Crafting an Enzyme-Linked Immunosorbent Assay (ELISA) Technique to Uncover COVID-19 Antibodies.

The COVID-19 pandemic, caused by the novel coronavirus SARS-CoV-2, has had a profound impact on global health. Rapid and accurate diagnostic tools are crucial for effective disease control and management. The enzyme-linked immunosorbent assay (ELISA) has emerged as a reliable and widely used method for detecting COVID-19 antibodies in patients, which develop in response to SARS-CoV-2 infection. While the ELISA technique is effective in identifying the presence of antibodies and thus confirming exposure to the virus, its role in predicting the clinical course and severity of the disease is limited. ELISA primarily confirms prior exposure to the virus or vaccination status, but it does not directly correlate antibody levels with the severity or progression of the disease. The variability in clinical outcomes is influenced by factors such as viral load, patient co-morbidities, genetic predispositions, and the timing of the immune response. ELISA has diverse applications in epidemiology, vaccination assessment, and therapeutic development. It determines antibody prevalence, aids in surveillance, and evaluates vaccine effectiveness and antibody protection duration. ELISA quantitatively measures antibody levels, providing insights into the immune response and treatment efficacy. Challenges include specialized facilities and personnel, cross-reactivity, and false results. Multiplex assays and integration with other diagnostics are future directions. In summary, ELISA is an essential tool in COVID-19 diagnostics, enabling precise assessment of the immune response and contributing to effective strategies. The development of point-of-care devices that integrate ELISA technology could enable rapid and accessible testing in various settings. Additionally, integrating ELISA with other diagnostic platforms could enhance the overall diagnostic capabilities for COVID-19. Despite challenges, ongoing advancements in ELISA technology, and its integration with other diagnostic approaches, hold promise for further improving COVID-19 diagnostics and management strategies.

Seroprevalence of SARS-CoV-2 nucleocapsid antibody among sex workers during the 5th epidemic wave with Omicron variant in Chiang Mai, Thailand.

Objectives: To investigate the seroprevalence of SARS-CoV-2 nucleocapsid antibodies (NC-Ab) in sex workers. Methods: A cross-sectional/observational study was conducted between March and December 2022 among sex workers living in Chiangmai, Thailand, aged over 18 years and who had engaged in sex work in the previous 12 months. Consenting individuals completed a questionnaire and had blood drawn. IgG-specific for SARS-CoV-2 nucleocapsid was assessed using Euroimmun anti-SARS-CoV-2 NCP ELISA (IgG). Results: 264 sex workers (52.3 % male) with a median age 31 years were included. The overall seroprevalence of SARS-CoV-2 NC-Ab was 42.4 % (44.2 % in males, 40.5 % in females). It was significantly higher among non-Thai than Thai sex workers (57.1 % vs. 37.1 %, p = 0.004) and among individuals who reported a history of COVID-19 as compared those who did not (54.9 % vs. 34.3 %, p = 0.036). NC-Ab seroprevalence did not differ by sex, age, receipt of COVID-19 vaccines, or the number of vaccine doses. SARS-CoV-2 NC-Ab seropositivity was significantly associated with being non-Thai, having monthly income >15,000 Baht, having received inactivated COVID-19 vaccines, and having been diagnosed with COVID-19. Conclusions: This study shows a high seroprevalence of NC-Ab among sex workers in Chiangmai, Thailand during the fifth epidemic wave with Omicron variant. This may be due to combined effects of high transmissibility of the Omicron variant and high-risk behavior of those individuals. Specific health education interventions are needed for this specific population.

Comparison of Post-Vaccination Response (Humoral and Cellular) to BNT162b2 in Clinical Cases, Kidney and Pancreas Transplant Recipient with Immunocompetent Subjects over Almost Two Years of Parallel Monitoring.

BACKGROUND: Vaccination is one of the most effective medical interventions to prevent infectious diseases. The introduction of vaccines against coronavirus acute respiratory syndrome 2 (SARS-CoV-2) was aimed at preventing severe illness and death due to coronavirus disease 2019 (COVID-19). Solid organ transplant recipients (SOTRs) are at high risk of infection with SARS-CoV-2 and serious effects associated with COVID-19, mainly due to the use of immunosuppressive therapies, which further cause suboptimal response to COVID-19 vaccination. AIM OF THE STUDY: We aimed to compare post-vaccination response to BNT162b2 in kidney-pancreas transplant recipient, specifically in immunocompetent individuals, over two years of simultaneous monitoring. METHODS: To determine the humoral response, the levels of the IgG and IgA anti-S1 antibodies were measured. To assess the cellular response to SARS-CoV-2, the released IFN-γ-S1 was determinate. RESULTS AND CONCLUSION: After primary vaccination, compared to immunocompetent subjects, SOTR showed lower seroconversion for both antibody classes. Only the additional dose produced antibodies at the level reached by the control group after the baseline vaccination. During the monitored period, SOTR did not achieve a positive cellular response in contrast to immunocompetent individuals, so in order to obtain longer protection, including immune memory, the adoption of booster doses of the vaccine should be considered.

Follow-Up of SARS-CoV-2 Antibody Levels in Belgian Nursing Home Residents and Staff Two, Four and Six Months after Primary Course BNT162b2 Vaccination.

When COVID-19 vaccines were implemented, nursing home residents (NHRs) and staff (NHS) in Belgium were prioritized for vaccination. To characterize the vaccine response over time in this population and to identify poorly responding groups, we assessed antibody concentrations two (T1), four (T2) and six months (T3) after primary course BNT162b2 vaccination in six groups of infection-naive/infection-primed NHRs/NHS, with/without comorbidity (NHRs only). Participant groups (N = 125 per group) were defined within a national serosurveillance study in nursing homes, based on questionnaire data. Dried blood spots were analyzed using ELISA for the quantification of SARS-CoV-2 S1RBD IgG antibodies. Among all groups, antibody concentrations significantly decreased between T1 and T2/T3, all with a ≥70% decrease at T3, except for infection-primed staff (-32%). Antibody concentrations among infection-naive NHRs were 11.96 times lower than those among infection-primed NHR, while the latter were comparable (x1.05) to infection-primed NHS. The largest proportion [13% (95% CI: 11-24%)] of vaccine non-responders was observed in the group of infection-naive NHRs with comorbidities. A longer interval between infection and vaccination (≥3 months) elicited higher antibody responses. Our data retrospectively show the necessity of timely COVID-19 booster vaccination. Infection-naive NHRs require special attention regarding immune monitoring in future epidemics or pandemics.

Immunological insights: assessing immune parameters in medical professionals exposed to SARS-CoV-2.

BACKGROUND: The immunological background responsible for the severe course of COVID-19 and the immune factors that protect against SARS-CoV-2 infection are still unclear. The aim of this study was to investigate immune system status in persons with high exposure to SARS-CoV-2 infection. METHODS: Seventy-one persons employed in the observation and infectious diseases unit were qualified for the study between November 2020 and October 2021. Symptomatic COVID-19 was diagnosed in 35 persons. Anti-SARS-CoV-2 antibodies were also found in 8 persons. Peripheral blood mononuclear cells subpopulations were analyzed by flow cytometry, and the concentrations of cytokines and anti-SARS-CoV-2 antibodies were determined by ELISA. RESULTS: The percentages of cytotoxic T lymphocytes (CTLs), CD28+ and T helper (Th) cells with invariant T-cell receptors were significantly higher in persons with symptomatic COVID-19 than in those who did not develop COVID-19' symptoms. Conversely, symptomatic COVID-19 persons had significantly lower percentages of: a) CTLs in the late stage of activation (CD8+/CD95+), b) NK cells, c) regulatory-like Th cells (CD4+/CTLA-4+), and d) Th17-like cells (CD4+/CD161+) compared to asymptomatic COVID-19' persons. Additionally, persons with anti-SARS-CoV-2 antibodies had a significantly higher lymphocyte count and IL-6 concentration than persons without these antibodies. CONCLUSION: Numerous lymphocyte populations are permanently altered by SARS-CoV-2 infection. High percentages of both populations: NK cells-as a part of the non-specific response, and T helper cells' as those regulating the immune response, could protect against the acute COVID-19 symptoms development. Understanding the immune background of COVID-19 may improve the prevention of this disease by identifying people at risk of a severe course of infection. TRIAL REGISTRATION: This is a retrospective observational study without a trial registration number.

Pre- and post-Ad26.COV2·S booster dose antibody levels predict COVID-19 disease risk.

Identifying immune correlates of risk following COVID-19 vaccine boosters has become paramount as a result of the challenges in generating additional efficacy data. The trial data described here was collected in the United States, with a large part of the study conduct coinciding with the emergence of the SARS-CoV-2 Omicron BA.1 variant. The vaccine trial involved the administration of a booster dose of Ad26.COV2·S at least 6 months after primary vaccination with either a single dose of Ad26.COV2·S or a 2-dose BNT162b2 vaccine regimen. Immunogenicity was assessed through Wuhan Spike binding antibodies (bAb), neutralizing antibodies (nAb), and Omicron BA.1 cross-neutralizing antibodies (nAb BA.1) at Day 1 (pre-boost), Day 15-, and 6-months post-boost. Immune correlates analyses demonstrate that, higher titers of bAb, nAb, and nAb BA.1 at Day 15 were consistently associated with a lower risk of symptomatic COVID-19 following a booster dose of Ad26.COV2·S, irrespective of the primary vaccine regimen. Similar results were obtained using multivariable analyses. Furthermore, Day 1 nAb levels against the Wuhan reference strain exhibited a statistically significant inverse relationship with the risk of symptomatic COVID-19. These findings highlight the value of assessing immune correlates for vaccine boosters, especially in the context of emerging SARS-CoV-2 variants. Clinical trials registration:NCT04999111.

Antibody response to non-mRNA SARS-CoV-2 vaccine in kidney transplant recipients.

BACKGROUND: Kidney transplant recipients (KTRs) show poor antibody response to the SARS-CoV-2 vaccine. There is limited data on immune response to non-mRNA vaccines in KTRs. We studied the antibody response to the SARS-CoV-2 non-mRNA vaccine in a cohort of kidney transplant recipients. METHODS: We included KTRs following up in the tertiary care transplant outpatient clinic from February to April 2022. SARS-CoV-2 spike protein IgG antibody titers were measured using chemiluminescence immunoassay. Data on demographic, clinical, and laboratory characteristics were collected, and patients were characterized by the history of Coronavirus disease 2019 (COVID-19) infection in the past and the number of vaccine doses received. Predictors of antibody response were obtained using multivariate regression analysis. RESULTS: S1/S2 IgG anti-SARS-CoV-2 antibodies were detected in 197 (87.94%) of 224 KTRs with a median [IQR] titers of 307.5 AU/ml [91 AU/ml - 400 AU/ml]. Neutralizing range antibody titers were found in 170/224 (75.9%) KTRs. Diabetes at the time of vaccination was associated with poorer antibody response (aOR 0.31, 95% confidence interval [CI] - 0.10, 0.90; p = 0.032) and vaccination with Covishield™ (ChAdOx1 nCoV- 19 Recombinant CoronaVirus Vaccine) showed higher antibody response as compared to Covaxin™ (BBV152) (aOR 5.04, 95% CI - 1.56, 16.22; p = 0.007). Graft dysfunction at baseline was associated with poorer antibody response. CONCLUSIONS: KTRs showed good antibody response after SARS-CoV-2 vaccination with non-mRNA vaccines. Diabetes and graft dysfunction were associated with poor seroconversion rates.

Seroprevalence of SARS-CoV-2 Antibodies and Associated Factors in Bamako, Mali: A Population-Based Cross-Sectional Study in September 2022.

BACKGROUND: The sero-epidemiological characteristics of SARS-CoV-2 infections in Mali are not yet well understood. This study assessed SARS-CoV-2 antibody seroprevalence and factors associated with antibody responses in the general population of Bamako, the capital city and epicenter of COVID-19, to assess the magnitude of the pandemic and contribute to control strategy improvements in Mali. METHODS: A cross-sectional survey was conducted in September 2022 to collect sociodemographic information, clinical characteristics, comorbid factors, and blood samples. ELISA was performed to determine anti-Spike (anti-S) and anti-RBD antibody levels. A total of 3601 participants were enrolled in REDCap. R-Studio was used for the statistical analysis. The chi-squared (χ2) test was used to compare the proportions across different groups. Logistic regression models were used to elucidate factors associated with antibody responses. RESULT: The sex ratio for female-to-male was 3.6:1. The most representative groups were the 20-29-year-olds (28.9%, n = 1043) and the 30-39-year-olds (26.9%, n = 967). The COVID-19 vaccine coverage among the participants was 35.8%, with vaccines from Covishield AstraZeneca (13.4%), Johnson & Johnson (16.7%), Sinovac (3.9%), and BioNTech Pfizer (1.8%). Overall, S protein and RBD antibody seroprevalences were remarkably high in the study population (98% and 97%, respectively). Factors such as youth (1-9 years old) and male sex were associated with lower SARS-CoV-2 antibody responses, whereas COVID-19 vaccinations were associated with increased antibody responses. CONCLUSION: This serosurvey demonstrated the high seroprevalence of SARS-CoV-2 antibodies and highlighted the factors influencing antibody responses, while clearly underlining an underestimation of the pandemic in Mali.

Incidence of SARS-CoV-2 during the Omicron wave: Results of a longitudinal serosurvey in Québec, Canada.

OBJECTIVES: Conventional serological approaches lack sensitivity for the detection of recent SARS-CoV-2 infections in vaccinated individuals, as these individuals exhibit a blunted anti-nucleocapsid (N) response. This limitation was recently addressed by the development of a "ratio-based approach", which compares longitudinally collected specimens. Here, we used this approach to estimate the incidence of SARS-CoV-2 infection and reinfection in Québec (Canada) during the Omicron wave. METHODS: Consenting plasma donors were included if they donated plasma before December 15, 2021 and during six consecutive periods of ~ 3 months between December 15, 2021 and July 7, 2023 (study period). Anti-N levels were measured with an enzyme-linked immunosorbent assay, and seroconversion was characterized by a ratio of ≥ 1.5 between the optical density of two consecutive samples. RESULTS: Among the 254 donors, the adjusted proportion of donors (95% confidence interval [CI]) with a new infection ranged between 18.1% (13.2‒23.0) and 24.2% (18.8‒29.7) over Periods 1-5 and fell to 7.9% (4.9‒11.0) during Period 6. During the study period, the proportion of newly infected donors decreased among those aged < 60 (Period 1 = 31.6%, Period 5 = 4.4%), but increased among those aged ≥ 70 (Period 1 = 0.3%, Period 6 = 10.3%). Throughout the study period, 72 (28.3%) reinfections occurred, including two seroconversion events in a single donor. Overall, 87.4% (95% CI = 82.7‒91.2) were infected by SARS-CoV-2 at least once during the study period. CONCLUSION: The vast majority of the Québec population may have been infected during the Omicron wave. This longitudinal survey demonstrates the usefulness of the "ratio-based approach" for identifying both new infections and reinfections in a vaccinated population.

RéSUMé: OBJECTIFS: Les approches sérologiques classiques démontrent un manque de sensibilité pour la détection des infections récentes par le SRAS-CoV-2 chez les personnes vaccinées, car ces dernières présentent une réponse anti-nucléocapside (N) peu élevée. Cette limitation a été récemment surmontée suite au développement d'une « approche basée sur les ratios ¼, qui compare des échantillons collectés de manière longitudinale. Nous avons utilisé cette approche pour estimer l'incidence de l'infection et de la réinfection par le SRAS-CoV-2 au Québec (Canada) pendant la vague Omicron. MéTHODES: Les donneurs de plasma consentants étaient inclus dans l'étude s'ils avaient donné du plasma avant le 15 décembre 2021 et pendant six périodes consécutives de 2 à 3 mois entre le 15 décembre 2021 et le 7 juillet 2023 (période d'étude). Les taux d'anti-N ont été mesurés par ELISA et la séroconversion a été caractérisée par un rapport ≥ 1,5 entre la densité optique de deux échantillons consécutifs. RéSULTATS: Parmi les 254 donneurs, le risque ajusté (IC 95 %) d'infection a varié entre 18,1 % (13,2‒23,0) et 24,2 % (18,8‒29,7) au cours des périodes 1 à 5 et a chuté à 7,9 % (4,9‒11,0) au cours de la période 6. Au cours de la période d'étude, le risque d'infection a diminué chez les donneurs âgés de moins de 60 ans (période 1 = 31,6 %, période 5 = 4,4 %), mais a augmenté chez ceux âgés de ≥ 70 ans (période 1 = 0,3 %, période 6 = 10,3 %). Tout au long de la période d'étude, 72 (28,3 %) réinfections se sont produites (c'est-à-dire deux événements de séroconversion chez un même donneur). Dans l'ensemble, 87,4 % (IC 95 % = 82,7‒91,2) ont été infectés par le SRAS-CoV-2 au moins une fois au cours de la période d'étude. CONCLUSION: La grande majorité de la population québécoise pourrait avoir été infectée lors de la vague Omicron. Cette enquête longitudinale démontre l'utilité de l'approche basée sur les ratios pour identifier les nouvelles infections et les réinfections dans une population vaccinée.

Cytokine, Anti-SARS-CoV-2 Antibody, and Neutralizing Antibody Levels in Conventional Blood Donors Who Have Recovered from COVID-19.

Background: At the beginning of the pandemic, COVID-19 convalescent plasma (CCP) containing anti-SARS-CoV-2 antibodies was suggested as a source of therapy. In the last 3 years, many trials have demonstrated the limited usefulness of CCP therapy. This led us to the hypothesis that CCP could contain other elements, along with the desired neutralizing antibodies, which could potentially prevent it from having a therapeutic effect, among them cytokines, chemokines, growth factors, clotting factors, and autoantibodies. Methods: In total, 39 cytokines were analyzed in the plasma of 190 blood donors, and further research focused on the levels of 23 different cytokines in CCP (sCD40L, eotaxin, FGF-2, FLT-3L, ractalkine, GRO-α, IFNα2, IL-1ß, IL-1RA, IL-5, IL-6, IL-8, IL-12, IL-13, IL-15, IL-17E, IP-10, MCP-1, MIP-1b, PDGF-AA, TGFα, TNFα, and TRAIL). Anti-SARS-CoV-2 antibodies and neutralizing antibodies were detected in CCP. Results: We found no significant differences between CCP taken within a maximum of 180 days from the onset of the first COVID-19 symptoms and the controls. We also made a comparison of the cytokine levels between the low neutralizing antibodies (<160) group and the high neutralizing antibodies (≥160) group and found there were no differences between the groups. Our research also showed no correlation either to levels of anti-SARS-CoV-2 IgG Ab or to the levels of neutralizing antibodies. There were also no significant changes in cytokine levels based on the period after the start of COVID-19 symptoms. Conclusions: No elements which could potentially be responsible for preventing CCP from having a therapeutic effect were found.

Seroprevalence and placental transfer of SARS-CoV-2 antibodies in unvaccinated pregnant women.

PURPOSE: Pregnant women are at risk of severe SARS-CoV-2 infection, potentially leading to obstetric and neonatal complications. Placental transfer of antibodies directed to SARS-CoV-2 may be protective against neonatal COVID-19, but this remains to be studied. We aimed to determine the seroprevalence of SARS-CoV-2 antibodies in a population of unvaccinated pregnant women and to determine the placental transfer of these antibodies. METHODOLOGY: A total of 1197 unvaccinated women with mostly unknown pre-study SARS-CoV-2 infection status, were tested at delivery for SARS-CoV-2 spike protein IgG antibodies during the first year of the pandemic. Umbilical cord samples were collected and assessed for seropositivity if the mother was seropositive. Maternal characteristics, pregnancy and neonatal outcomes and data on SARS-CoV-2 infection were extracted from medical records. RESULTS: Specific IgG were detected in 258 women (21.6%). A significant placental transfer to the newborn was observed in 81.3% of cases. The earlier in the 2nd and 3rd trimesters that the mother had contracted the disease and the more symptomatic she was, the greater the likelihood of transplacental transfer of IgG to her newborn. CONCLUSION: Approximately one in five women had detectable anti-SARS-CoV-2 spike protein IgG antibodies at delivery during the first year of the pandemic, and these antibodies were significantly transferred to their fetuses. This research provides further evidence to better understand the dynamics of the placental transfer of SARS-CoV-2 IgG antibodies from mothers to their newborns, which is necessary to improve vaccination strategies.

SARS-CoV-2 antibodies in adolescents living with perinatally acquired HIV.

Data on children and adolescents with HIV and coronavirus disease 2019 (COVID-19) co-infection are limited. Clinical and antibody data related to COVID-19 infection in adolescents living with perinatally acquired HIV (ALPHIV) and originally enrolled in the Children with HIV Early Antiretroviral Therapy (CHER) study were collected. We present a descriptive analysis of 53 ALPHIV who were tested for anti-SARS-CoV-2 antibodies. Just over half (53%) of the adolescents tested had positive anti-SARS-CoV-2 antibodies with only one participant describing a prior history of possible symptomatic infection. Contribution: The study contributes to the understanding of SARS-CoV-2 infection and vaccination practices in HIV-positive adolescents.

Delayed Antibody Response in the Acute Phase of Infection Is Associated with a Lower Mental Component of Quality of Life in Survivors of Severe and Critical COVID-19.

Background: The long-term sequelae of coronavirus disease 2019 (COVID-19) significantly affects quality of life (QoL) in disease survivors. Delayed development of the adaptive immune response is associated with more severe disease and a worse prognosis in COVID-19. The effects of delayed immune response on COVID-19 sequelae and QoL are unknown. Methods: We conducted a prospective study to assess the relationship between the delayed antibody response in the acute phase of infection in naïve unvaccinated patients suffering from severe or critical COVID-19 and their QoL 12 months after hospital discharge. The 12-item Short Form Survey (SF-12) questionnaire was used for assessment of QoL. The SF-12 evaluates both mental and physical components of QoL, incorporating a mental component score (MCS-12) and a physical component score (PCS-12). A delayed antibody response was defined as testing negative for anti-spike SARS-CoV-2 antibodies at the time of hospital admission. Results: The study included 274 patients (154 men and 120 women). Of the enrolled patients, 144 had a delayed immune response. These patients had a significantly lower MCS-12 (p = 0.002), but PCS-12 (p = 0.397) was not significantly different at the 12-month follow-up compared to patients with positive anti-spike SARS-CoV-2 antibodies. The MCS-12 at the time of follow-up was negatively associated with delayed antibody response irrespective of possible confounders (p = 0.006; B = 3.609; ηp2 = 0.035; 95% CI = 1.069-6.150). An MSC-12 below 50 points at the time of follow-up was positively associated with delayed antibody response (p = 0.001; B = 1.092; OR = 2.979; 95% CI = 1.554-5.711). Conclusions: This study confirmed that, in patients with severe and critical COVID-19, a negative result for anti-spike SARS-CoV-2 antibodies at the time of hospital admission is associated with a lower mental component of QoL in unvaccinated patients naïve to COVID-19 one year after hospital discharge.

Quantification of SARS-CoV-2 monoclonal IgG mass fraction by isotope dilution mass spectrometry.

The availability of serology assays to measure antibodies against the SARS coronavirus 2 (SARS-CoV-2) expanded rapidly during the Covid-19 pandemic. The interchangeable use of such assays to monitor disease progression and immune protection requires their standardization, for which suitably characterized monoclonal antibody materials can be useful. The methods, based on isotope dilution mass spectrometry, to value assign the mass fraction of such a material in solution within the context of an international interlaboratory comparison study (CCQM-P216) are described. The mass fraction in solution of a humanized IgG monoclonal antibody (mAb) against the SARS-CoV-2 Spike glycoprotein in the study sample has been value assigned through a combination of liquid chromatography, isotope dilution mass spectrometry (LC-ID-MS) methods and size exclusion chromatography with UV detection (SEC-UV). The former were developed for the quantification of amino acids and proteotypic peptides as surrogate analytes of the mAb while the latter was applied for the determination of the relative monomeric mass fraction. High-resolution mass spectrometry (hrMS) allowed the molecular weight evaluation and ruled out the presence of significant impurities. Method trueness was assessed using a subclass homologous IgG1 material value assigned by amino acid analysis. The assigned mass fraction of monomeric SARS-CoV-2 IgG in solution was 390 ± 16 mg/g. The associated expanded uncertainty originated mainly from acid hydrolysis variability and Trypsin/Lys-C digestion variability and efficiency.

Low antibody levels associated with significantly increased rate of SARS-CoV-2 infection in a highly vaccinated population from the US National Basketball Association.

SARS-CoV-2 antibody levels may serve as a correlate for immunity and could inform optimal booster timing. The relationship between antibody levels and protection from infection was evaluated in vaccinated individuals from the US National Basketball Association who had antibody levels measured at a single time point from September 12, 2021, to December 31, 2021. Cox proportional hazards models were used to estimate the risk of infection within 90 days of serologic testing by antibody level (<250, 250-800, and >800 AU/mL1 ), adjusting for age, time since last vaccine dose, and history of SARS-CoV-2 infection. Individuals were censored on date of booster receipt. The analytic cohort comprised 2323 individuals and was 78.2% male, 68.1% aged ≤40 years, and 56.4% vaccinated (primary series) with the Pfizer-BioNTech mRNA vaccine. Among the 2248 (96.8%) individuals not yet boosted at antibody testing, 77% completed their primary vaccine series 4-6 months before testing and the median (interquartile range) antibody level was 293.5 (interquartile range: 121.0-740.5) AU/mL. Those with levels <250 AU/mL (adj hazard ratio [HR]: 2.4; 95% confidence interval [CI]: 1.5-3.7) and 250-800 AU/mL (adj HR: 1.5; 95% CI: 0.98-2.4) had greater infection risk compared to those with levels >800 AU/mL. Antibody levels could inform individual COVID-19 risk and booster scheduling.

The Impact of Clinical Factors and SARS-CoV-2 Variants on Antibody Production in Vaccinated German Healthcare Professionals Infected Either with the Delta or the Omicron Variant.

BACKGROUND: The aim of the rapid introduction of vaccines during the COVID-19 pandemic was a reduction in SARS-CoV-2 transmission and a less frequent occurrence of severe COVID-19 courses. Thus, we evaluated COVID-19 severity in vaccinated individuals to examine variant-specific symptom characteristics and their clinical impact on the serological immune response. METHODS: A total of 185 individuals previously vaccinated against and infected with the SARS-CoV-2 Delta (B.1.617.2) or Omicron (BA.4 and BA.5) variant, were enrolled for anti-SARS-CoV-2 anti-N- and anti-RBD/S1-Ig level detection. A structured survey regarding medical history was conducted. RESULTS: In 99.5 percent of cases, outpatient treatment was satisfactory. Specific symptoms associated with variants included ageusia and anosmia in patients with Delta infections and throat pain in Omicron infections. Among Delta-infected individuals with specific symptoms, significantly higher levels of anti-N antibodies were observed. CONCLUSION: Our study identified variant-specific differences in the amount of SARS-CoV-2 antibody production and COVID-19 symptoms. Despite this, vaccinated individuals with Omicron or Delta infections generally experienced mild disease courses. Additionally, asymptomatic individuals exhibit lower anti-SARS-CoV-2 antibody levels, indicating a clinical correlation between disease-specific antibodies and distinct symptoms, particularly in the case of the Delta variant. In follow-up studies, exploring post-COVID syndrome and focusing on cognitive symptoms in the acute phase of Omicron infections is crucial as it has the potential to longitudinally impact the lives of those affected.

Prognostic value of anti-SARS-CoV-2 antibodies: a systematic review.

OBJECTIVES: Globally, over 772 million cases of COVID-19 have been reported. New variants of interest with corresponding spikes in case numbers continue to be identified. Vulnerable patients, including older adults or patients with severe comorbidities, continue to be at risk. A large body of evidence has been accumulated regarding anti-SARS-CoV-2-antibodies and COVID-19 but the usefulness of antibody measurements remains unclear. This systematic review aims to assess the prognostic value of anti-SARS-CoV-2-antibodies and their usefulness for guiding booster vaccinations. METHODS: Studies in English and published between January 2020 and October 2023 were included. Studies that relied on multiparameter-models or comprised fewer than 100 participants were excluded. PubMed and via the WHO COVID-19 research database, Embase and Medline databases were searched. Study selection and quality assessment was conducted independently by two researchers. RESULTS: After screening 1,160 studies, 33 studies comprising >30 million individuals were included. Anti-SARS-CoV-2-antibodies were strongly associated with reduced risk of SARS-CoV-2-infection and better outcomes, including mortality. Risk of infection and COVID-19 severity decreased with increasing antibody levels. CONCLUSIONS: Anti-SARS-CoV-2-antibodies are useful for early identification of high-risk patients and timely adjustment of therapy. Protective thresholds may be applied to advise booster vaccinations but verification in separate cohorts is required.