Humoral Immune Response in SARS-CoV- 2 Infection and Its Therapeutic Relevance

Antibody production in response to infection or vaccination is a crucial process to combat and prevent infectious diseases. Regarding SARS-CoV-2, different features have been observed and literature still lacks consensus about it. Here, we discuss the production of antibodies during SARS-CoV-2 infection and its therapeutic relevance. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2022.

Declined Humoral Immunity of Kidney Transplant Recipients to SARS-CoV-2 Vaccines.

Background: Kidney transplant recipients (KTRs) commonly suffer from impaired immunity. KTRs' compromised immune response to COVID-19 vaccines indicates urgent revision of immunisation policies. Methods: A cross-sectional study was conducted in Madinah, Saudi Arabia of 84 KTRs who had received at least one dose of a COVID-19 vaccine. ELISA was used to evaluate anti-spike SARS-CoV-2 IgG and IgM antibody levels in blood samples obtained one month and seven months after vaccination. Univariate and multivariate analyses were performed to identify associations between seropositive status and factors such as the number of vaccine doses, transplant age, and immunosuppressive therapies. Results: The mean age of KTRs was 44.3 ± 14.7 years. The IgG antibody seropositivity rate (n=66, 78.5%) was significantly higher than the seronegativity rate (n=18, 21.4%) in the whole cohort (p<0.001). In KTRs seroconverting after one month (n=66), anti-SARS-CoV-2 IgG levels declined significantly between one month (median [IQR]:3 [3-3]) and seven months (2.4 [1.7-2.6]) after vaccination (p<0.01). In KTRs with hypertension, IgG levels significantly decreased between one and seven months after vaccination (p<0.01). IgG levels also decreased significantly in KTRs with a transplant of >10 years (p=0.02). Maintenance immunosuppressive regimens (triple immunosuppressive therapy and steroid-based and antimetabolite-based regimens) led to a significant decrease in IgG levels between the first and second sample (p<0.01). KTRs receiving three vaccine doses showed higher antibody levels than those receiving a single dose or two doses, but the levels decreased significantly between one (median [IQR]: 3 [3-3]) and seven months (2.4 [1.9-2.6]) after vaccination (p<0.01). Conclusion: KTRs' humoral response after SARS-CoV-2 vaccination is dramatically inhibited and wanes. Antibody levels show a significant decline over time in KTRs with hypertension; receiving triple immunosuppressive therapy or steroid-based or antimetabolite-based regimens; receiving mixed mRNA and viral vector vaccines; and with a transplant of >10 years.

[COVID-19 infections and effectiveness of the vaccination among healthcare workers]. / A COVID­19-fertozés és a védooltások hatásosságának vizsgálata egészségügyi dolgozókon.

INTRODUCTION: New variants of the SARS-CoV-2 coronavirus are constantly appearing, causing the COVID-19 pandemic. From November 2021, most infections were caused by the Omicron coronavirus variant. OBJECTIVE: The aim of this prospective observational cohort study was to estimate the incidence of COVID-19 infections in the high-risk healthcare workers after two BNT162b2 mRNA Pfizer-BioNTech vaccines and the subsequent booster vaccine, as well as the effectiveness, the safety and the humoral immune response of the vaccines. METHOD: We started the two Pfizer-BioNTech ((BNT162b29) vaccinations of healthcare workers of the Polyclinic of the Hospitaller Brothers of St. John between January 07 and March 08, 2021. The choice of the type and timing of the third booster vaccination was voluntary. The workers were followed up between January 07, 2021 and June 29, 2022. The infection rate, adverse events of the vaccination, risk factors to infection and the kinetics of anti-spike (S) antibody and anti-nucleocapsid (N) antibody serum level were evaluated. RESULTS: The data of 294 healthcare workers - 96 medical doctors, 127 nurses and 71 workers in hospital - who had at least three antibody level measurements were analyzed. The third booster vaccine was given to 280 workers, the distribution of the vaccines was the following: Pfizer-BioNTech (BNT162b29) vaccine (n = 210), Moderna COVID-19 (mRNA-1273) vaccine (n = 37), Sinopharm COVID-19 vaccine (n = 21), Janssen COVID-19 (n = 10), AstraZeneca (ChAdOx1 nCoV-19) vaccine (n = 2). Infection occurred in 121 cases (41%) during the observation period. The course of the COVID-19 infections was mostly mild (97%) and recovered within a week. During the observational period, 2 workers died: a 56-year-old woman died after two vaccinations for reason unrelated to COVID-19 infection, and a 58-year-old man died after the booster vaccination, following COVID-19 infection. The incidence of infection did not correlate with age, sex, comorbidities, smoking, occupation and BMI. The median titre of anti-S antibody serum level increased one month after the second vaccination of the basic immunization (1173.0 U/ml) and decreased slowly until the 8th month (678.5-625.8-538.0 U/ml) after the basic vaccination. One month after the booster vaccination, the median titre of anti-S antibody serum level increased significantly (16 535 U/ml), and showed a decreasing trend in the 3rd month after the booster vaccination (9697.7 U/ml). An exceptionally high S antibody serum level increasing after the basic (>10 000 U/mL) and booster (>60 000 U/m) vaccination showed a correlation with prior COVID-19 infection. The median cut-off index (COI) of anti-N antibody was not affected by vaccination, the increasing of the titre is related to the infection. CONCLUSION: The booster vaccination had less effect on the infection caused by Omicron variant, but the course of the infection was milder. Compared to the basic immunisation, the booster vaccination caused a significant increase in the S antibody level. An exceptionally high S antibody level correlated with prior COVID-19 infection. Orv Hetil. 2023; 164(5): 163-171.

Humoral and cellular immune responses after three or four doses of BNT162b2 in patients with hematological malignancies.

OBJECTIVES: Initial responses to coronavirus disease 2019 vaccination are impaired in patients with hematological malignancies. We investigated immune responses after three or four doses of BNT162b2 in patients with myeloid and lymphoid malignancies compared to controls, and identified risk factors for humoral and cellular nonresponse 1 year after first vaccination. METHODS: In 407 hematological patients (45 myeloid, 362 lymphoid) and 98 matched controls, we measured immunoglobulin G (IgG) and neutralizing antibodies specific for the receptor-binding domain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at baseline, 3 weeks, 2, 6, and 12 months, and interferon-γ release at 12 months. RESULTS: In patients with lymphoid malignancies, SARS-CoV-2 receptor-binding domain IgG concentration and mean neutralizing capacity was lower than in controls at all time points. A diagnosis of chronic lymphocytic B-cell leukemia (CLL) or lymphoma was associated with humoral nonresponse at 12 months compared to having multiple myeloma/amyloidosis (p < .001 and p = .013). Compared to controls, patients with lymphoid malignancies had increased risk of cellular nonresponse. A lymphoma diagnosis was associated with lower risk of cellular nonresponse compared to patients with multiple myeloma/amyloidosis, while patients with CLL had comparable response rates to patients with multiple myeloma/amyloidosis (p = .037 and p = .280). CONCLUSIONS: In conclusion, long-term humoral and cellular immune responses to BNT162b2 were impaired in patients with lymphoid malignancies.

Longitudinal Follow-Up of the Immunity to SARS-CoV-2 in Health Care Workers in Argentina: Persistence of Humoral Response and Neutralizing Capacity after Sputnik V Vaccination.

SARS-CoV-2 vaccine protection has encountered waning of immune response and breakthrough infections. The hybrid immune response generated by the combination of vaccination and infection was shown to offer higher and broader protection. Here, we present a seroprevalence study of anti-SARS-CoV-2 spike/RBD IgG in 1,121 health care workers immunized with Sputnik V and a follow-up of humoral response at 2 and 24 weeks postvaccination (wpv), including neutralizing antibody response (NAT) against ancestral, Gamma, and Delta variants. The first seroprevalence study showed that among 122 individuals with one dose, 90.2% were seropositive versus 99.7% seropositivity among volunteers with the complete two-dose regimen. At 24 wpv, 98.7% of the volunteers remained seropositive, although antibody levels decreased. IgG levels and NAT were higher in individuals that had acquired COVID-19 previous to vaccination than in naive individuals at 2 and 24 wpv. Antibody levels dropped over time in both groups. In contrast, IgG levels and NAT increased after vaccine breakthrough infection. At 2 wpv, 35/40 naive individuals had detectable NAT against SARS-CoV-2 Gamma and 6/40 against Delta. In turn, 8/9 previously infected individuals developed a neutralizing response against SARS-CoV-2 Gamma and 4/9 against Delta variants. NAT against variants followed a trajectory similar to NAT against ancestral SARS-CoV-2, and breakthrough infection led to an increase in NAT and complete seroconversion against variants. In conclusion, Sputnik V-induced humoral response persisted at 6 months postvaccination, and hybrid immunity induced higher levels of anti-S/RBD antibodies and NAT in previously exposed individuals, boosted the response after vaccination, and conferred wider breadth of protection. IMPORTANCE Since December 2020, Argentina has begun a mass vaccination program. The first vaccine available in our country was Sputnik V, which has been approved for use in 71 countries with a total population of 4 billion people. Despite all the available information, there are fewer published studies on the response induced by Sputnik V vaccination compared to that of other vaccines. Although the global political context has paralyzed the verification by the WHO of the efficacy of this vaccine, our work aims to add new clear and necessary evidence to Sputnik V performance. Our results contribute to general knowledge of the humoral immune response developed by vaccines based on viral vector technology, highlighting the higher immune protection conferred by hybrid immunity and reinforcing the importance of completing vaccination schedules and booster doses to maintain adequate antibody levels.

Characterization of the Humoral Immune Response to Porcine Epidemic Diarrhea Virus Infection under Experimental and Field Conditions Using an AlphaLISA Platform.

Coronavirus infections are a continuous threat raised time and again. With the recent emergence of novel virulent strains, these viruses can have a large impact on human and animal health. Porcine epidemic diarrhea (PED) is considered to be a reemerging pig disease caused by the enteropathogenic alphacoronavirus PED virus (PEDV). In the absence of effective vaccines, infection prevention and control through diagnostic testing and quarantine are critical. Early detection and differential diagnosis of PEDV infections increase the chance of successful control of the disease. Therefore, there is a continuous need for development of reduced assay-step protocols, no-wash, high-throughput immunoassays. This study described the characterization of the humoral immune response against PEDV under experimental and field conditions using a rapid, sensitive, luminescent proximity homogenous assay (AlphaLISA). PEDV IgG and IgA antibodies were developed toward the beginning of the second week of infection. PEDV IgG antibodies were detected for at least 16 weeks post-exposure. Remarkably, the serum IgA levels remained high and relatively stable throughout the study, lasting longer than the serum IgG response. Overall, AlphaLISA allows the detection and characterization of pathogen-specific antibodies with new speed, sensitivity, and simplicity of use. Particularly, the bridge assay constitutes a rapid diagnostic that substantially improves upon the "time to result" metric of currently available immunoassays.

Elevated SARS-CoV-2-Specific Antibody Levels in Patients with Post-COVID Syndrome.

With the routine use of effective severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines, the number of life-threatening coronavirus disease 2019 (COVID-19) courses have largely been reduced. However, multiple COVID-19 convalescents, even after asymptomatic to moderate disease, suffer from post-COVID syndrome, with relevant limitations in daily life. The pathophysiologic mechanisms of post-COVID syndrome are still elusive, with dysregulation of the immune system suggested as a central mechanism. Here, we assessed COVID-19 post-infectious symptoms (5-6 months after PCR-confirmed acute infection) together with the humoral immune response against SARS-CoV-2 in non-hospitalized COVID-19 convalescents, early (5-6 weeks) and late (5-6 months) after their first positive SARS-CoV-2 PCR result. Convalescents reporting several post-infectious symptoms (>3) showed higher anti-spike and anti-nucleocapsid antibody levels 5-6 weeks after PCR-confirmed infection with the latter remained increased 5-6 months after positive PCR. Likewise, a higher post-infectious symptom score was associated with increased antibody levels. Of note, convalescents displaying neuro-psychiatric symptoms such as restlessness, palpitations, irritability, and headache, as well as general symptoms such as fatigue/reduced power had higher SARS-CoV-2-specific antibody levels compared with asymptomatic cases. The increased humoral immune response in convalescents with post-COVID syndrome might be useful for the detection of individuals with an increased risk for post-COVID syndrome.

COVID-19 Vaccine Booster Shot Preserves T Cells Immune Response Based on Interferon-Gamma Release Assay in Inflammatory Bowel Disease (IBD) Patients on Anti-TNFα Treatment.

Immune-modifying treatment in inflammatory bowel disease (IBD) impairs the humoral response. The role of T lymphocytes in this setting is still unclear. This study aims to assess if a booster shot (third dose) of BNT162b2 mRNA COVID-19 vaccine enhanced the humoral response and elicited cellular immunity in IBD patients on different immuno-therapy regimens compared to healthy controls (HCs). Five months after a booster dose, serological and T-cell responses were assessed. The measurements were described using geometric means with 95% confidence intervals. The differences between study groups were assessed by Mann-Whitney tests. Seventy-seven subjects (n = 53 IBD patients and n = 24 HCs), who were fully vaccinated and not previously SARS-CoV-2 infected, were recruited. Regarding the IBD patients, 19 were affected by Crohn's disease and 34 by ulcerative colitis. During the vaccination cycle, half of the patients (53%) were on stable treatment with aminosalicylates, and 32% were on biological therapy. No differences in antibody concentrations between IBD patients and HCs, nor T-cell responses, were found. Stratifying IBD patients based on the type of treatment (anti-TNFα agents vs. other treatment regimens), a decrease only in antibody titer (p = 0.008), but not in cellular response, was observed. Even after the COVID-19 vaccine booster dose, the TNFα inhibitors selectively decreased the humoral immune response compared to patients on other treatment regimens. The T-cell response was preserved in all study groups. These findings highlight the importance of evaluating T-cell immune responses following COVID-19 vaccination in a routine diagnostic setting, particularly for immunocompromised cohorts.

Consistent neutralization of circulating omicron sub-variants by hybrid immunity up to 6 months after booster vaccination.

The current COVID-19 vaccination program requires frequent booster vaccination to maintain sufficient neutralization levels against immune evasive SARS-CoV-2 variants. However, prior studies found more potent and durable immune response in convalescing individuals, raising the possibility of less frequent booster vaccination for them. Here, we conducted a longitudinal immunological study based on two prospective cohorts of booster vaccinated convalescing COVID-19 patients or healthcare workers (HCW) without COVID-19 history in Xiangyang, China. Comparing to 1-month post-boosting, pseudovirus neutralization titers (pVNT50) of ancestral Wuhan-Hu-1 and circulating omicron sub-variants BA.5, BF.7, BA.4.6, BA.2.75, and BA.2.75.2 spikes were stable or even increased in convalescing samples at 6-month post-boosting, when HCW samples showed substantial drop of neutralization titers across the spectrum. Variant-to-Wuhan-Hu-1 pVNT50 ratios showed no significant variation during the 17 months from pre-vaccination to 6-month post-boosting in convalescing individuals, indicating that the high durability of hybrid immunity was likely sustained by continuously improving neutralization potency that compensated immune decay. Our data provide mechanistic insight into prior epidemiological findings that vaccine-elicited humoral immune response was more durable in convalescing individuals than those without SARS-CoV-2 infection, and suggest further research into potential extension of boosting intervals for convalescing individuals.

The accelerated waning of immunity and reduced effect of booster in patients treated with bDMARD and tsDMARD after SARS-CoV-2 mRNA vaccination.

Objectives: This study aimed to assess the duration of humoral responses after two doses of SARS-CoV-2 mRNA vaccines in patients with inflammatory joint diseases and IBD and booster vaccination compared with healthy controls. It also aimed to analyze factors influencing the quantity and quality of the immune response. Methods: We enrolled 41 patients with rheumatoid arthritis (RA), 35 with seronegative spondyloarthritis (SpA), and 41 suffering from inflammatory bowel disease (IBD), excluding those receiving B-cell-depleting therapies. We assessed total anti-SARS-CoV-2 spike antibodies (Abs) and neutralizing Ab titers 6 months after two and then after three doses of mRNA vaccines compared with healthy controls. We analyzed the influence of therapies on the humoral response. Results: Patients receiving biological or targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs) showed reduced anti-SARS-CoV-2 S Abs and neutralizing Ab titers compared with HC or patients receiving conventional synthetic (cs)DMARDs 6 months after the first two vaccination doses. Anti-SARS-CoV-2 S titers of patients with b/tsDMARDs declined more rapidly, leading to a significant reduction in the duration of vaccination-induced immunity after two doses of SARS-CoV-2 mRNA vaccines. While 23% of HC and 19% of patients receiving csDMARDs were without detectable neutralizing Abs 6 months after the first two vaccination doses, this number was 62% in patients receiving b/tsDMARDs and 52% in patients receiving a combination of csDMARDs and b/tsDMARDs. Booster vaccination led to increased anti-SARS-CoV-2 S Abs in all HC and patients. However, anti-SARS-CoV-2 S Abs after booster vaccination was diminished in patients receiving b/tsDMARDs, either alone or in combination with csDMARDs compared to HC. Conclusion: Patients receiving b/tsDMARDs have significantly reduced Abs and neutralizing Ab titers 6 months after mRNA vaccination against SARS-CoV-2. This was due to a faster decline in Ab levels, indicating a significantly reduced duration of vaccination-induced immunity compared with HC or patients receiving csDMARDs. In addition, they display a reduced response to a booster vaccination, warranting earlier booster vaccination strategies in patients under b/tsDMARD therapy, according to their specific Ab levels.

Immunogenicity of COVID-19 mRNA vaccines in patients with acute myeloid leukemia and myelodysplastic syndrome.

Immunocompromised patients are susceptible to complications from severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). The mRNA vaccines BNT162b2 and mRNA-1273 are effective in immunocompetent adults, but have diminished activity in immunocompromised patients. We measured anti-spike SARS-CoV-2 antibody (anti-S) response, avidity, and surrogate neutralizing antibody activity in COVID-19 vaccinated patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Anti-S was induced in 89% of AML and 88% of MDS patients, but median levels were significantly lower than in healthy controls. SARS-CoV-2 antibody avidity and neutralizing activity from AML patients were significantly lower than controls. Antibody avidity was significantly greater in patients after mRNA-1273 versus BNT162b2; there were trends toward higher anti-S levels and greater neutralizing antibody activity after mRNA-1273 vaccination. Patients with AML and MDS are likely to respond to COVID-19 mRNA vaccination, but differences in anti-S levels, avidity, and neutralizing antibody activity may affect clinical outcomes and require further study.

In-depth characterization of long-term humoral and cellular immune responses to COVID-19m-RNA vaccination in multiple sclerosis patients treated with teriflunomide or alemtuzumab.

BACKGROUND: The impact of disease-modifying therapies on the efficacy to mount appropriate immune responses to COVID-19 vaccination in patients with multiple sclerosis (MS) is currently under investigation. OBJECTIVE: To characterize long-term humoral and cellular immunity in mRNA-COVID-19 MS vaccinees treated with teriflunomide or alemtuzumab. METHODS: We prospectively measured SARS-COV-2 IgG, memory B-cells specific for SARS-CoV-2 RBD, and memory T-cells secreting IFN-γ and/or IL-2, in MS patients vaccinated with BNT162b2-COVID-19 vaccine before, 1, 3 and 6 months after the second vaccine dose, and 3-6 months following vaccine booster. RESULTS: Patients were either untreated (N = 31, 21 females), under treatment with teriflunomide (N = 30, 23 females, median treatment duration 3.7 years, range 1.5-7.0 years), or under treatment with alemtuzumab (N = 12, 9 females, median time from last dosing 15.9 months, range 1.8-28.7 months). None of the patients had clinical SARS-CoV-2 or immune evidence for prior infection. Spike IgG titers were similar between untreated, teriflunomide and alemtuzumab treated MS patients both at 1 month (median 1320.7, 25-75 IQR 850.9-3152.8 vs. median 901.7, 25-75 IQR 618.5-1495.8, vs. median 1291.9, 25-75 IQR 590.8-2950.9, BAU/ml, respectively), at 3 months (median 1388.8, 25-75 1064.6-2347.6 vs. median 1164.3 25-75 IQR 726.4-1399.6, vs. median 837.2, 25-75 IQR 739.4-1868.5 BAU/ml, respectively), and at 6 months (median 437.0, 25-75 206.1-1161.3 vs. median 494.3, 25-75 IQR 214.6-716.5, vs. median 176.3, 25-75 IQR 72.3-328.8 BAU/ml, respectively) after the second vaccine dose. Specific SARS-CoV-2 memory B cells were detected in 41.9%, 40.0% and 41.7% of subjects at 1 month, in 32.3%, 43.3% and 25% at 3 months, and in 32.3%, 40.0%, 33.3% at 6 months following vaccination in untreated, teriflunomide treated and alemtuzumab treated MS patients, respectively. Specific SARS-CoV-2 memory T cells were found in 48.4%, 46.7% and 41.7 at 1 month, in 41.9%, 56.7% and 41.7% at 3 months, and in 38.7%, 50.0%, and 41.7% at 6 months, of untreated, teriflunomide-treated and alemtuzumab -treated MS patients, respectively. Administration of a third vaccine booster significantly increased both humoral and cellular responses in all patients. CONCLUSIONS: MS patients treated with teriflunomide or alemtuzumab achieved effective humoral and cellular immune responses up to 6 months following second COVID-19 vaccination. Immune responses were reinforced following the third vaccine booster.

Persistence of IgG COVID-19 antibodies: A longitudinal analysis.

Background and aim: The kinetics of antibody production in response to coronavirus disease 2019 (COVID-19) infection is not well-defined yet. This study aimed to evaluate the antibody responses to SARS-CoV-2 and its dynamics during 9-months in a cohort of patients infected during the first phase of the pandemic. As a secondary aim, it was intended to evaluate the factors associated with different concentrations of IgG antibodies. Methods: A prospective cohort study was conducted from June 2020 to January 2021. This study recruited a convenience sample of adult individuals who where recently diagnosed with COVID-19 and were living in mainland Portugal. A total of 1,695 blood samples were collected from 585 recovered COVID-19 patients up to 9 months after SARS-CoV-2 acute infection. A blood sample was collected at baseline and three, 6 and 9 months after SARS-CoV-2 acute infection to assess the concentration of IgG antibody against SARS-CoV-2. Results: The positivity rate of IgG reached 77.7% in the first 3 months after symptom onset. The IgG persists at all subsequent follow-up time-points, which was 87.7 and 89.2% in the 6th and 9th months after symptom onset, respectively. Three distinct kinetics of antibody response were found within the 9 months after infection. Kinetic 1 (K1) was characterized by a constant low IgG antibody concentration kinetic (group size: 65.2%); kinetic 2 (K2), composed by constant moderate IgG kinetic (group size: 27.5%) and kinetic 3 (K3) characterized by higher IgG kinetic (group size: 7.3%). People with ≥56 years old (OR: 3.33; CI 95%: [1.64; 6.67]; p-value: 0.001) and symptomatic COVID-19 (OR: 2.08; CI 95%: [1.08; 4.00]; p-value: 0.031) had higher odds of a "Moderate IgG kinetic." No significant association were found regarding the "Higher IgG kinetic." Conclusion: Our results demonstrate a lasting anti-spike (anti-S) IgG antibody response at least 9 months after infection in the majority of patients with COVID-19. Younger participants with asymptomatic disease have lower IgG antibody positivity and possibly more susceptible to reinfection. This information contributes to expanding knowledge of SARS-CoV-2 immune response and has direct implications in the adoption of preventive strategies and public health policies.

COVID-19 booster dose induces robust antibody response in pregnant, lactating, and nonpregnant women.

BACKGROUND: Although emerging data during the SARS-CoV-2 pandemic have demonstrated robust messenger RNA vaccine-induced immunogenicity across populations, including pregnant and lactating individuals, the rapid waning of vaccine-induced immunity and the emergence of variants of concern motivated the use of messenger RNA vaccine booster doses. Whether all populations, including pregnant and lactating individuals, will mount a comparable response to a booster dose is not known. OBJECTIVE: This study aimed to profile the humoral immune response to a COVID-19 messenger RNA booster dose in a cohort of pregnant, lactating, and nonpregnant age-matched women. STUDY DESIGN: This study characterized the antibody response against ancestral Spike and Omicron in a cohort of 31 pregnant, 12 lactating, and 20 nonpregnant age-matched controls who received a BNT162b2 or messenger RNA-1273 booster dose after primary COVID-19 vaccination. In addition, this study examined the vaccine-induced antibody profiles of 15 maternal-to-cord dyads at delivery. RESULTS: Receiving a booster dose during pregnancy resulted in increased immunoglobulin G1 levels against Omicron Spike (postprimary vaccination vs postbooster dose; P=.03). Pregnant and lactating individuals exhibited equivalent Spike-specific total immunoglobulin G1, immunoglobulin M, and immunoglobulin A levels and neutralizing titers against Omicron compared with nonpregnant women. Subtle differences in Fc receptor binding and antibody subclass profiles were observed in the immune response to a booster dose in pregnant vs nonpregnant individuals. The analysis of maternal and cord antibody profiles at delivery demonstrated equivalent total Spike-specific immunoglobulin G1 in maternal and cord blood, yet higher Spike-specific FcγR3a-binding antibodies in the cord relative to maternal blood (P=.002), consistent with the preferential transfer of highly functional immunoglobulin. Spike-specific immunoglobulin G1 levels in the cord were positively correlated with the time elapsed since receiving the booster dose (Spearman R, .574; P=.035). CONCLUSION: Study data suggested that receiving a booster dose during pregnancy induces a robust Spike-specific humoral immune response, including against Omicron. If boosting occurs in the third trimester of pregnancy, higher Spike-specific cord immunoglobulin G1 levels are achieved with greater time elapsed between receiving the booster and delivery. Receiving a booster dose has the potential to augment maternal and neonatal immunity.

Humoral immune response in COVID-19 patients and novel design of lateral flow assay strip for simultaneous rapid detection of IgA/IgM/ IgG antibodies against the SARS-CoV-2 virus

At the end of 2019, a novel coronavirus (CoV) appeared in Wuhan, China and has since spread to several countries and regions throughout the world. The disease caused by the novel CoV has been officially named CoV disease 2019 (COVID-19). This study provides additional data for the presence of anti-SARS-CoV-2 IgM and IgG antibodies in COVID-19 patients in Vietnam. The study also presents the development of a lateral flow immunoassay (LFA) strip for rapid simultaneous detection of the IgA/IgM/IgG antibodies against the SARS-CoV-2 virus in COVID-19 patients. The properties of the LFA test strip were evaluated by testing specimens from COVID-19 positive and negative patients confirmed by real-time PCR. Reproducibility and repeatability reached 100%. The LFA test strip did not show any cross-reactivity with 13 different pathogens and did not interfere with anticoagulants. The sensitivity and specificity of the LFA test strips were evaluated with 633 clinical samples and were found to be 91.06% and 98.74%, respectively. The Kappa statistics showed almost perfect agreement and correlation between our test strip and real-time PCR results (k coefficient = 0.902). From the obtained results, it could be suggested that the LFA test strip is a useful tool for rapid detection of antibodies against SARS-CoV-2 to accelerate epidemiological surveillance, to determine the situation of exposure to SARS-CoV-2, and to increase the diagnostic accuracy of the real-time PCR method for COVID-19. © 2023 Ngo, et al.

BNT162b2 COVID-19 vaccination elicited protective robust immune responses in pediatric patients with inborn errors of metabolism.

Introduction: SARS-CoV-2 infection can lead to a life-threatening acute metabolic decompensation in children with inborn errors of metabolism (IEM), so vaccination is mandatory. However, IEMs can also impair innate or adaptive immunity, and the impact of these immune system alterations on immunogenicity and vaccine efficacy is still unknown. Here, we investigated humoral immune responses to the BNT162b2 mRNA COVID-19 vaccine and clinical outcomes in pediatric IEM patients. Methods: Fifteen patients between 12-18 years of age with a confirmed diagnosis of IEM, and received BNT162b2 were enrolled to the study. Patients with an anti-SARS-CoV-2 IgG concentration >50 AU/mL before vaccination were defined as "COVID-19 recovered" whereas patients with undetectable anti-SARS-CoV-2 IgG concentration were defined as "COVID-19 naïve". Anti-SARS-CoV-2 Immunoglobulin G (IgG) and SARS-CoV-2 neutralizing antibody (nAb) titers were measured to assess humoral immune response. Results: Anti-SARS-CoV-2 IgG titers and nAb IH% increased significantly after the first dose. The increase in antibody titers after first and second vaccination remained significant in COVID-19 naïve patients. Complete anti-SARS-CoV-2 IgG seropositivity and nAb IH% positivity was observed in all patients after the second dose. Vaccination appears to be clinically effective in IEM patients, as none of the patients had COVID-19 infection within six months of the last vaccination. Discussion: Humoral immune response after two doses of BNT162b2 in pediatric IEM patients was adequate and the immune response was not different from that of healthy individuals.

A hepatitis B virus core antigen-based virus-like particle vaccine expressing SARS-CoV-2 B and T cell epitopes induces epitope-specific humoral and cell-mediated immune responses but confers limited protection against SARS-CoV-2 infection.

The hepatitis B virus core antigen (HBcAg) tolerates insertion of foreign epitopes and maintains its ability to self-assemble into virus-like particles (VLPs). We constructed a ∆HBcAg-based VLP vaccine expressing three predicted severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) B and T cell epitopes and determined its immunogenicity and protective efficacy. The recombinant ∆HBcAg-SARS-CoV-2 protein was expressed in Escherichia coli, purified, and shown to form VLPs. K18-hACE2 transgenic C57BL/6 mice were immunized intramuscularly with ∆HBcAg VLP control (n = 15) or ∆HBcAg-SARS-CoV-2 VLP vaccine (n = 15). One week after the 2nd booster and before virus challenge, five ∆HBcAg-SARS-CoV-2 vaccinated mice were euthanized to evaluate epitope-specific immune responses. There is a statistically significant increase in epitope-specific Immunoglobulin G (IgG) response, and statistically higher interleukin 6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1) expression levels in ∆HBcAg-SARS-CoV-2 VLP-vaccinated mice compared to ∆HBcAg VLP controls. While not statistically significant, the ∆HBcAg-SARS-CoV-2 VLP mice had numerically more memory CD8+ T-cells, and 3/5 mice also had numerically higher levels of interferon gamma (IFN-γ) and tumor necrosis factor (TNF). After challenge with SARS-CoV-2, ∆HBcAg-SARS-CoV-2 immunized mice had numerically lower viral RNA loads in the lung, and slightly higher survival, but the differences are not statistically significant. These results indicate that the ∆HBcAg-SARS-CoV-2 VLP vaccine elicits epitope-specific humoral and cell-mediated immune responses but they were insufficient against SARS-CoV-2 infection.

Immune response in ofatumumab treated multiple sclerosis patients after SARS-CoV-2 vaccination.

Objective: The pandemic induced by SARS-CoV-2 has huge implications for patients with immunosuppression that is caused by disorders or specific treatments. Especially approaches targeting B cells via anti-CD20 therapy are associated with impaired humoral immune response but sustained cellular immunity. Ofatumumab is a human anti-CD20 directed antibody applied in low dosages subcutaneously, recently licensed for Multiple Sclerosis (MS). Effects of early ofatumumab treatment on alterations of immune cell composition and immune response towards SARS-CoV-2 are incompletely understood. Methods: We here investigated immune cell alterations in early ofatumumab (Ofa) treated patients and effects on humoral (titer, neutralization capacity against wild type, Delta and Omicron) and cellular immune responses in Ofa treated MS patients following a third vaccination against SARS-CoV-2 compared to healthy controls. Results: We show that a mean treatment duration of three months in the Ofa group led to near complete B cell depletion in line with altered composition of certain CD4+ T cell subpopulations such as enhanced frequencies of naive and a decrease of non-suppressive regulatory T cells (Tregs). Titer and neutralization capacity against SARS-CoV-2 variants was impaired while cellular immune response was sustained, characterized by a strong T helper 1 profile (Th1). Interpretation: In summary, low dosage ofatumumab treatment elicits sustained depletion of B cells in line with alterations of immune cells, mainly Tregs. This is associated with impaired humoral immune response towards SARS-CoV-2 vaccination but preserved, Th1 driven cellular immunity adding crucial information regarding early effects of low dosage anti-CD20 therapy on humoral and cellular immunity.