Seroconversion Research Articles

Immunogenicity and Antibody Persistence of the Inactivated Quadrivalent Influenza Vaccine in Pediatric Patients Post-Chemotherapy or Allogeneic Hematopoietic Stem Cell Transplantation Versus Healthy Controls

Pediatric patients who have undergone hematopoietic stem cell transplantation (HSCT) or chemotherapy are at increased risk for severe influenza complications, necessitating annual vaccination. This study evaluated the immunogenicity and antibody persistence of the 2021–2022 seasonal quadrivalent influenza vaccine in pediatric patients post-HSCT or chemotherapy, compared to healthy controls. A prospective cohort study included 80 pediatric participants divided into three groups: chemotherapy (n = 33), HSCT (n = 27), and healthy controls (n = 20). All participants were vaccinated with the 2021–2022 GC FLU Quadrivalent vaccine. Hemagglutination inhibition (HI) assays measured seroprotection rates (SPR), geometric mean titers (GMT), and seroconversion rates (SCR) for the four vaccine antigens (A/H1N1, A/H3N2, B/Victoria, B/Yamagata) at one, three, and six months post-vaccination. At one month post-vaccination, all groups met the 70% SPR threshold for A/H1N1 and A/H3N2, but not for B/Victoria. For B/Yamagata, the SPR was low in the chemotherapy and HSCT groups (18.18% and 33.33%, respectively), compared to 80.00% in controls (p < 0.0001 and p = 0.0015). While A/H1N1 and A/H3N2 GMTs were protective in all groups, only controls achieved protective levels for B/Yamagata. Over time, the control group maintained >70% SPR for A/H1N1 up to six months, but the chemotherapy and HSCT groups declined by three and six months, respectively. For A/H3N2, the SPR in controls dropped below 70% at three months, while it remained above 70% in the chemotherapy and HSCT groups until three months. None of the groups achieved protective GMTs for B strains at three or six months. Pediatric patients post-HSCT or chemotherapy demonstrated a comparable immune response to healthy controls for A/H1N1 and A/H3N2, but the rapid decline in A/H1N1 antibody levels suggests the need for ongoing monitoring and adjusted vaccination schedules. The poor response to B antigens, particularly B/Yamagata, underscores the need for improved vaccination strategies in these vulnerable populations.

National survey to estimate seroprevalence for toxoplasmosis among pregnant women in France, 2021

Abstract Background Toxoplasmosis during pregnancy can result in congenital malformations and fetal death. In France, universal antenatal screening and monthly re-testing of seronegative pregnant women has been established since the 1970s. However, decreasing Toxoplasma gondii seroprevalence among pregnant women and lower incidence of congenital toxoplasmosis may challenge the cost-effectiveness of such programs. The aim of this study was to estimate the current seroprevalence among pregnant women participating in the 2021 national perinatal survey (ENP). Methods All adult women giving birth in France between 15-21 March 2021 were invited to participate in the ENP. Data collected included demographic information, nationality, socio-economic status, education level and Toxoplasma gondii serology. We classified a woman as seropositive if she had IgG antibodies prior to pregnancy or seroconverted during it. Univariable and multivariable regression analyses using Poisson model were conducted to estimate prevalence ratios (PRs) and identify significant factors associated with seropositivity. Results Among the 15,605 participating women, 0.22% seroconverted during pregnancy. The overall seroprevalence was 25.95%. Seropositivity was higher with increasing age (∼5% per 5 years), among residents of French overseas territories Guadeloupe/Saint Martin (PRs:1.07; 95%-CI: 1.03-1.10), La Réunion (PRs:1.10; 95%-CI: 1.08-1.13) and Mayotte (PRs:1.27; 95%-CI: 1.23-1.31), with lower education (PRs:1.22; 95%-CI: 1.04-1.42) and African nationality (PRs:1.11; 95%-CI: 1.02-1.20). Conclusions High seroprevalence for Toxoplasma gondii was found in older women, which may reflect their higher risk of past exposure. The observed geographical differences in seroprevalence may mirror dietary and environmental diversity. Declining seroprevalence among pregnant women in France can affect screening effectiveness and warrants a comprehensive review to determine appropriate future prevention strategies. Key messages • Older women and residents of French overseas territories show higher toxoplasmosis seroprevalence, possibly due to past exposure risks and diverse diets/environments. • Declining toxoplasmosis seroprevalence among pregnant women in France can affect screening effectiveness and warrants a comprehensive review to determine appropriate future prevention strategies.

Immune Response Against Influenza in a Cohort of Repeatedly Vaccinated Adults During the 2017/2018 and 2018/2019 Seasons

Background/Objectives: The influenza vaccination of healthcare workers (HCWs) is recommended each autumn and winter season by the relevant authorities in EU/EEA countries. The objective of this study was to evaluate the impact of repeated trivalent influenza vaccine (TIV) uptake during the 2017/2018 and 2018/2019 seasons on vaccine-derived immunity against influenza. Methods: A cohort study of HCWs vaccinated with an annual TIV was conducted from October 2017 to June 2019. The protective antibodies against the influenza vaccine strains were assessed at three time points: prior to vaccination and at one and six months following vaccination for each season. Sera were tested by hemagglutination inhibition assay. Participants were grouped according to their history of TIV vaccination over four seasons (since 2015/16), with the groups designated as “frequently vaccinated” (≥3 vaccines) and “occasionally vaccinated” (≤2 vaccines). Seroprevalence, geometric mean titer (GMT) and seroconversion rate were compared between the frequently and occasionally vaccinated groups. Results: A total of 97 healthcare workers (HCWs) were enrolled in the study; 49 HCWs participated in both seasons. Thirty-two (43.2%) and forty-three (59.7%) individuals had ≥3 vaccines since 2015/2016, at recruitment and during the 2017/2018 and 2018/2019 influenza seasons, respectively. One month following vaccination, HCWs who had received occasional vaccinations demonstrated a higher prevalence of protective antibodies and a greater GMT for both influenza A(H1N1)pdm09 and A(H3N2) viruses. For influenza B Victoria, the frequently vaccinated HCWs demonstrated a higher seroprevalence rate, seroconversion, and GMT. Conclusions: Previous vaccination can influence the immune response, although without substantially compromising the immunogenicity of annual influenza vaccination. HCW annual influenza vaccination is required to re-establish and maintain the antibody titers against influenza.

Regional variation in the landscape ecology of West Nile virus sentinel chicken seroconversion in Florida.

How landscape composition and configuration impact the distribution of multi-vector and multi-host mosquito vector-borne disease systems, such as West Nile virus (WNV), remains challenging because of complex habitat and resource requirements by hosts and vectors that affect transmission opportunities. We examined correlations between landscape composition and configuration and 2018 WNV sentinel chicken seroconversion in Florida, USA across the state and within five National Oceanic Atmospheric Administration (NOAA) bioclimatic regions to understand strength and variation of landscape effects during an elevated transmission year. Although few landscape studies have examined WNV in Florida, we expected higher percentages of residential or medium-developed landscapes and more fragmented landscapes would be positively correlated with WNV seroconversion owing to the main mosquito vector habitats and avian host distributions. However, we expected to find variation in the importance of forest, wetland, and agriculture landscapes across bioclimatic regions in the state. WNV seroconversion rates were calculated using Florida 2018 Department of Health WNV sentinel chicken seroconversion data from 187 flocks maintained by mosquito control programs. Percent land cover and edge density metrics were calculated for multiple land cover classes and within multiple buffer distances from chicken coops using 2019 National Land Cover Data. We used binomial generalized linear mixed effects models to calculate the importance of landscape metrics to WNV seroconversion. We found no statewide predictors of seroconversion, but as expected, the importance of landscape varied across regions. In the north-central part of the state, we found higher seroconversion in less populated suburban areas while higher seroconversion in south-central Florida was correlated with fragmented forested areas within 0.5 km of coops and intact woody wetland areas within 2 km of coops. This work corroborates previous findings that consistent landscape predictors of WNV are difficult to identify across broader geographic areas and sets the stage for additional work that incorporates climate and landscapes interactions for a greater understanding of WNV ecology in this geographic region.

Immunogenicity to Herpes Zoster recombinant subunit vaccine in immune-mediated rheumatic patients under treatment with JAK inhibitors.

Patients with immune-mediated rheumatic diseases (IMRDs) face an elevated risk of varicella-zoster virus infection (VZV), and herpes zoster (HZ). Treatment with immunosuppressors further increases the risk. A new recently approved adjuvant recombinant inactive vaccine, offers safe protection against HZ. However, limited data exist on the efficacy of this new vaccine in patients with IMRDs treated with JAK inhibitors. We aimed to characterize B cell and T cell immune responses elicited by the HZ recombinant subunit vaccine in patients with IMRDs under treatment with JAK inhibitors, and to identify factors that might be associated with reduced immunogenicity, and therefore reduced protection. We investigated humoral, and cellular CD4 and CD8 immune responses following a two-dose regimen of the recombinant inactive vaccine in 43 patients with rheumatic diseases treated with different JAK inhibitors. The responses were compared with age, gender and disease-matched healthy controls. Patients with IMRDs treated with JAK inhibitors showed reduced seroconversion rate (63% vs 100% and lower VZV IgG titers (1222 ± 411 vs 3048 ± 556, p< 0.0001) as compared with healthy controls. Functional T CD4 (IL-2 plus IFN-γ secretion) and T CD8 (Granzyme A and/or Granzyme B secretion) immune responses were also significantly diminished in IMRDs patients. Negative correlation was found between VZV antibody titers and age, specific treatments (baricitinib, tofacitinib, upadacitinib), cumulative methotrexate and glucocorticoid doses, history of multiple DMARDs, and treatment duration with JAK inhibitors. Functional T-CD4 responses but not functional T-CD8 responses also showed similar negative correlations. Positive associations were observed between functional T-CD4 and T-CD8 responses. Our study provides valuable insights into the immune responses elicited by the recombinant inactive vaccine in patients with IMRDs treated with JAK inhibitors. In these patients we have observed a broad impact on the adaptive humoral and cellular immune responses, suggesting a potential reduction in protection against herpes zoster infection and VHZ reactivation.

Development and validation of a multivariable nomogram predictive of hepatitis B e antigen seroconversion after pregnancy in hepatitis B virus-infected mothers

Background and aimsCurrent guidelines are controversial regarding the continuation of nucleos(t)ide analogues (NAs) therapy after delivery in Hepatitis B virus (HBV)-infected pregnant women. The postpartum period may be an opportune moment for achieving hepatitis B e antigen (HBeAg) seroconversion earlier with constant NAs therapy due to the restoration of immune function after delivery. We investigated prenatal and pregnant factors associated with HBeAg seroconversion after pregnancy and developed a nomogram to predict HBeAg seroconversion rates, aiding decision-making for optimal management in women.MethodsWe retrospectively included 489 HBeAg-positive mothers as the training cohort from January 2014 to December 2018 and prospectively enrolled 94 patients as the external validation cohort from January 2019 to December 2021 at the First Affiliated Hospital of Xi’an Jiaotong University. In the training cohort, independent predictors were identified using the least absolute shrinkage and selection operator (LASSO) regression algorithm. Subsequently, multivariate logistic regression was employed to establish the nomogram. Model performance was assessed using the area under the receiver operating characteristic curve (AUC), calibration plots, and decision curve analysis (DCA). Both discrimination and calibration were evaluated through bootstrapping with 1,000 resamples. The external validation cohort was subsequently used to validate the nomogram.ResultsFactors such as pregnancy hepatitis flare (OR: 5.122, 95% CI: 2.725–9.928, p &amp;lt; 0.001), NAs therapy after delivery (OR: 15.051, 95% CI: 6.954–37.895, p: &amp;lt;0.001), hepatitis B surface antigen (HBsAg) (OR: 0.549, 95% CI: 0.366–0.812, p: 0.003) and HBV DNA level at delivery (OR: 0.785, 95% CI: 0.619–0.986, p: 0.041) were included in the final risk model. The AUC in the training set was 0.873 (95% CI: 0.839–0.904). The calibration curve of the nomogram closely resembled the ideal diagonal line. DCA showed a significantly better net benefit in the model. External validation also confirmed the reliability of the prediction nomogram. The AUC in the external validation set was 0.889 (95% CI: 0.801–0.953). The calibration curve for the external validation set was in close proximity to the ideal diagonal line. DCA also demonstrated a significant net benefit associated with the predictive model, consistent with the findings in the training set. Finally, the nomogram has been translated into an online risk calculator that is freely available to the public (https://wendyzhong.shinyapps.io/DynNomapp/).ConclusionWe developed a nomogram based on prenatal and pregnant factors to estimate HBeAg seroconversion after delivery in women. This tool provides clinicians with a precise and effective way to identify individuals likely to undergo HBeAg seroconversion postpartum, aiding in decision-making for optimal management.

A comparison of the therapeutic efficacy of Tenofovir Disoproxil Fumarate and Entecavir in patients with chronic Hepatitis-B

Objective: To compare the therapeutic efficacy of tenofovir disoproxil fumarate (TDF) and entecavir (ETV) in patients with chronic Hepatitis-B (CHB). Methods: This retrospective study included 110 patients with CHB who received treatment at The First People’s Hospital of Linping District, Hangzhou from January 2021 to January 2023. Clinical data of the patients were reviewed and the patients were classified according to the treatment received: TDF group (n=53, patients received TDF treatment) and ETV group (n=57, patients received ETV treatment). Hepatitis-B virus deoxyribonucleic acid (HBV DNA) levels, liver function indicators, hepatitis-B e antigen (HBeAg) seroconversion rate, alanine transaminase (ALT) normalization rate, HBV DNA negative conversion rate, overall efficacy, and incidence of adverse reactions were compared. Results: The total efficacy of the treatment in the TDF group was 94.33%, significantly higher than that in the ETV group (78.95%; P&lt;0.05). After the treatment, the HBV DNA levels in both groups decreased compared to pretreatment levels, and were significantly lower in the TDF group compared to the ETV group (P&lt;0.05). Both groups showed significant post-treatment improvement in liver function that was markedly better in the TDF group compared to the ETV group (P&lt;0.05). The HBeAg seroconversion rate, ALT normalization rate, and HBV DNA conversion rate in the TDF group were significantly higher compared to the ETV group (P&lt;0.05). There was no difference in the incidence of adverse reactions between the two groups. Conclusions: Compared with ETV, TDF has comparable adverse reaction profile but has more significant clinical effects in patients with CHB, improving HBeAg seroconversion rate, ALT normalization rate, and HBV DNA negative conversion rate. TDF is associated with lower HBV DNA levels after treatment and better improvements in liver function of patients. doi: https://doi.org/10.12669/pjms.40.10.10307 How to cite this: Wang H, Wu L. A comparison of the therapeutic efficacy of Tenofovir Disoproxil Fumarate and Entecavir in patients with chronic Hepatitis-B. Pak J Med Sci. 2024;40(10):2390-2394. doi: https://doi.org/10.12669/pjms.40.10.10307 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Ongoing transmission of trachoma in low prevalence districts in Mozambique: results from four cross-sectional enhanced impact surveys, 2022

Mozambique is making progress towards elimination of trachoma as a public health problem, but in some districts trachomatous inflammation—follicular (TF) prevalence remains above the 5% elimination threshold despite years of various interventions, including antibiotic mass drug administration. To characterize transmission in four districts, we incorporated testing of ocular infection and serology into routine trachoma impact surveys (TIS) in August 2022. We examined residents aged ≥ 1 year for trachoma and collected information on household water, sanitation, and hygiene. Among children aged 1–9 years, we tested conjunctival swabs for Chlamydia trachomatis nucleic acid and dried blood spots for C. trachomatis antibodies. We modeled age-dependent seroprevalence to estimate seroconversion rate (SCR). We examined 4841 children aged 1–9 years. TF prevalence ranged between 1.1 and 6.0% with three districts below the 5% threshold. PCR-confirmed infection prevalence ranged between 1.1 and 4.8%, and Pgp3 seroprevalence ranged between 8.8 and 24.3%. Pgp3 SCR was 1.9 per 100 children per year in the district with the lowest TF prevalence. Two other districts with TF < 5% had SCR of 5.0 and 4.7. The district with TF ≥ 5% had a SCR of 6.0. This enhanced TIS furthered understanding of transmission in these districts and provides information on additional indicators for monitoring trachoma programs.

Impact of Sex, Age and Body Habitus on RBD-specific Antibody Response After Two Doses of Sinopharm BBIBP-CorV Vaccine

Background: Mongolia started its nationwide vaccination campaign against COVID-19 on 23 February 2021 after receiving the first batch of the inactivated BBIBP-CorV. Age and body habitus of vaccinees may be associated with the immune effecter functions. Several systematic reviews and meta-analyses suggested lower immunogenicity of vaccines against SARS-CoV-2 infection in the older adult population and obese individuals. We aimed to establish a possible relationship between post-vaccine seroconversion rate and some biometric characteristics in the Mongolian cohort of vaccinees after two shots of the Sinopharm BBIBP-CorV vaccine. Materials and Methods: We collected serum samples from 846 eligible vaccinees before the first dose of the BBIBP-CorV vaccine and 21-28 days after the second dose of the same vaccine. Anti-SARS-CoV-2 Receptor Binding Domain (RBD) Immunoglobulin class G (IgG) and M (IgM) titer were measured in all samples. Results: 686 (81.1%) of 846 vaccinees received the Sinopharm BBIBP-CorV vaccine demonstrated seroconversion. Vaccinees with seroconversion had a younger mean age and lower mean body-mass index (BMI) than non-responders. Seroconversion rate according to age of vaccinees tends to decrease and obese vaccinees demonstrated a greater portion among non-responders. The Optimal Cut-Point (OCP) of age for seroconversion was found to differ significantly in male and female vaccinees. BMI has shown prediction ability for seroconversion only in male vaccinees but not in females. Using Receiver Operating Characteristics (ROC) analysis, we found 39 years for males and 41 years for females as a crucial milestone increasing the probability of seronegativity 2.5 times on average. A BMI higher than 29.1kg/m2 in male vaccinees was considered an acceptable predictor for seroconversion increasing the probability of seronegativity 2.4 times on average. Conclusion: The above findings allow us to summarize the sex-adjusted approach to biometric characteristics has an improved predictiveness for post-vaccine antibody response.

Did We Overreact? Insights on COVID-19 Disease and Vaccination in a Large Cohort of Immune-Mediated Inflammatory Disease Patients during Sequential Phases of the Pandemic (The BELCOMID Study)

Introduction: As the COVID-19 pandemic becomes an endemic state, still many questions remain regarding the risks and impact of SARS-CoV-2 infection and vaccination in patients with immune-mediated inflammatory diseases (IMIDs) who were excluded from the phase 3 COVID-19 vaccination trials. Methods: The BELCOMID study collected patient data and serological samples from a large, multicentric IMID patient cohort that was prospectively followed during sequential stages of the pandemic. Patients were stratified according to vaccination status into five groups across three sampling periods. Interactions between SARS-CoV-2 infection, COVID-19 vaccination status, IMID-treatment modalities and IMID course were explored. Results: In total, 2165 patients with IBD, a dermatological or rheumatological IMID participated. SARS-CoV-2 infection rates increased over the course of the pandemic and were highest in IMID patients that had refused every vaccine. After baseline COVID-19 vaccination, serologic spike (S)-antibody responses were attenuated by particular types of immune-modulating treatment: anti-TNF, rituximab, JAKi, systemic steroids, combined biologic/immunomodulator treatment. Nonetheless, S-antibody concentration increased progressively in patients who received a booster vaccination, reaching 100% seroconversion rate in patients who had received two booster vaccines. Previous SARS-CoV-2 infection was found as a predictor of higher S-antibody response. Patients who had refused every vaccine showed the lowest rates of S-seroconversion (53.8%). Multiple logistic regression did not identify previous SARS-CoV-2 infection as a risk factor for IMID flare-up. Furthermore, no increased risk of IMID flare-up was found with booster vaccination. Conclusions: Altogether, the BELCOMID study provides evidence for the efficacy and safety of COVID-19 vaccination and confirms the importance of repeated booster vaccination in IMID patients.

Antibody responses to re-immunization in recipients of allogeneic hematopoietic cell transplantation

Abstract Background Immunologic memory against vaccine-preventable diseases is often lost after an allogeneic hematopoietic cell transplant (allo-HCT), therefore recipients are required to be re-immunized after allo-HCT to regain immunity against these infections. But the response to vaccination after an allo-HCT can be highly variable and is not well understood. We performed a single center retrospective study to examine immunization practices and determine the rate of vaccine protection and seroconversion following vaccination after allo-HCT. Methods Electronic medical records (EMR) from patients ≤18 years of age who underwent allo-HCT at St. Jude Childrens’ Research Hospital between 2005 - 2021 were reviewed. Clinical information and serology results before and after completion of the immunizations series were extracted from the EMR. The vaccines included in this analysis were diphtheria, measles, mumps, rubella (MMR), varicella, and polio. Protection was evaluated only for infections with established immune correlates. Seroconversion was defined as 4-fold increase in titers for vaccines with quantitative antibody assays, or as a change from negative to positive IgG for vaccines with qualitative antibody tests. Results 760 patients were included in this cohort. Demographic and clinical data are summarized in Table 1. The mean age at allo-HCT was 10.4 years, most were male (56.8%) and white (74.6%). Acute leukemia accounted for 66.4% of allo-HCT recipients. Conditioning was myeloablative for 53.45%, and reduced intensity for 37.9%. Most received transplants from mismatched-related donors, (44.9%), followed by matched unrelated donors (35.4%) and matched related donors (19.5%). The number of patients who received the full vaccination series at our institution differed by vaccine and ranged from 41-150, and the respective subsets with available pre-vaccination and post-vaccination titers ranged from 24-93. The median time from transplant to initiation of immunizations was 12 months (range: 6-58) for non-live vaccines, 25 months (range: 23, 63) for MMR vaccine, and 28 months (range: 16, 117)) for varicella vaccine. Protection post immunization varied, with less patients demonstrating protections for mumps (79%) and measles (82%) (Figure 1). Seroconversion also varied among the different vaccine components and types of vaccines. Conclusion Current strategies to re-immunize patients after allo-HCT do not provide protection to all patients. Understanding the factors associated with suboptimal immune responses is critical for advancing our knowledge in this area. Whether time-based approaches combined with immune reconstitution data are required to further optimize protection remains unclear. Additionally, different vaccine schedules (i.e., higher doses) may be required in these patients. Figure 1. Protection and seroconversion rate by vaccine target.

Safety and efficacy of COVID-19 vaccines in children and adolescents with cancer.

Children with cancer have a higher morbidity and mortality due to COVID-19. Vaccination of children with cancer is important. In this study, we aimed to investigate the effectiveness and side effects of the COVID-19 vaccines in children and adolescents with cancer. Fifty-eight patients from four centers were included in the study. Antibodies to the SARS-CoV-2 spike protein levels were measured. Vaccine-related complaints were recorded. There were 33 male and 25 female patients. The mean age was 16.9±2.3 years. In 58.6% of cases, the diagnosis was hematological malignancies. Twenty patients were currently under treatment, while 38 had completed the treatment. Forty-eight patients received chemotherapy ± radiotherapy, 13 received immunotherapy, and 3 underwent stem cell transplantation. CoronoVac© and BNT162b2© vaccines were administered in 24% and 76%, respectively. The mean antibody level was lower in patients who received CoronaVac© than that of BNT162b2©, although the difference was not significant. The levels were within the protective limits in both groups. No significant difference was found in antibody levels according to diagnostic subgroups, treatment status, type of treatment, line of treatment, disease status and time between vaccines and measurement of antibody level. The most common side effects were pain at the injection site (37.9%) and malaise/weakness (17.2%), which were similar for both vaccines. Our study showed that both mRNA and inactivated vaccines elicit an immune response in children with cancer. However, the seroconversion rate is significantly higher in mRNA vaccines. Side effects were similar to those seen in healthy children.

A Phase II/III multicenter randomized single blind non-inferiority immunogenicity and safety study of TeddyVac™ vaccine of Human Biologicals Institute in healthy subjects of 10 years to 60 years of age

Background WHO and other health agencies recommend that tetanus toxoid (TT) should be replaced by tetanus-diphtheria (Td) vaccine taking into consideration the low coverage and waning immunity, especially for diphtheria. In this randomised, multicentre, non-inferiority study, the immunogenicity and safety of TeddyVac™ vaccine of Human Biologicals Institute were compared with an existing brand. Methods The study involved 444 eligible subjects in two age groups at four centres across India. Group A included subjects of 18–60 years and Group B subjects of 10–18 years of age. All subjects received single dose of either TeddyVac™ or the comparator vaccine as per randomisation. Blood samples for antibody titre estimation were collected before vaccination and 4–6 weeks after vaccination. Immunogenicity was assessed by estimating seroconversion rate, seroprotection rate, and geometric mean titres of antibodies. Safety was evaluated by collection and analysis of data on solicited and unsolicited adverse events. Results Overall, 441 subjects completed the study. Both the vaccine arms showed comparable seroconversion after a single dose for both the components. Both arms showed increase in seroprotection and geometric mean titres after a single dose of vaccination for both vaccine components, being significantly better for the diphtheria component in the test vaccine arm. Only few minor local and systemic adverse events were observed in both the vaccine arms. No serious adverse event was reported. Conclusion The study results indicate that the TeddyVac™ vaccine is immunogenic, safe and non-inferior to the comparator Vaccine when administered to healthy subjects of 10 to 60 years of age. CTRI Registration number CTRI/2021/07/035112

M protein ectodomain-specific immunity restrains SARS-CoV-2 variants replication.

The frequent occurrence of mutations in the SARS-CoV-2 Spike (S) protein, with up to dozens of mutations, poses a severe threat to the current efficacy of authorized COVID-19 vaccines. Membrane (M) protein, which is the most abundant viral structural protein, exhibits a high level of amino acid sequence conservation. M protein ectodomain could be recognized by specific antibodies; however, the extent to which it is immunogenic and provides protection remains unclear. We designed and synthesized multiple peptides derived from coronavirus M protein ectodomains, and determined the secondary structure of specific peptides using circular dichroism (CD) spectroscopy. Enzyme-linked immunosorbent assay (ELISA) was utilized to detect IgG responses against the synthesized peptides in clinical samples. To evaluate the immunogenicity of peptide vaccines, BALB/c mice were intraperitoneally immunized with peptide-keyhole limpet hemocyanin (KLH) conjugates adjuvanted with incomplete Freund's adjuvant (IFA). The humoral and T-cell immune responses induced by peptide-KLH conjugates were assessed using ELISA and ELISpot assays, respectively. The efficacy of the S2M2-30-KLH vaccine against SARS-CoV-2 variants was evaluated in vivo using the K18-hACE2 transgenic mouse model. The inhibitory effect of mouse immune serum on SARS-CoV-2 virus replication in vitro was evaluated using microneutralization assays. The subcellular localization of the M protein was evaluated using an immunofluorescent staining method, and the Fc-mediated antibody-dependent cellular cytotoxicity (ADCC) activity of the S2M2-30-specific monoclonal antibody (mAb) was measured using an ADCC reporter assay. Seroconversion rates for ectodomain-specific IgG were observed to be high in both SARS-CoV-2 convalescent patients and individuals immunized with inactivated vaccines. To assess the protective efficacy of the M protein ectodomain-based vaccine, we initially identified a highly immunogenic peptide derived from this ectodomain, named S2M2-30. The mouse serum specific to S2M2-30 showed inhibitory effects on the replication of SARS-CoV-2 variants in vitro. Immunizations of K18-hACE2-transgenic mice with the S2M2-30-keyhole limpet hemocyanin (KLH) vaccine significantly reduced the lung viral load caused by B.1.1.7/Alpha (UK) infection. Further mechanism investigations reveal that serum neutralizing activity, specific T-cell response and Fc-mediated antibody-dependent cellular cytotoxicity (ADCC) correlate with the specific immuno-protection conferred by S2M2-30. The findings of this study suggest that the antibody responses against M protein ectodomain in the population most likely exert a beneficial effect on preventing various SARS-CoV-2 infections.

A booster dose of SARS-COV-2 vaccine improves suboptimal seroconversion rates in patients with inflammatory bowel disease. Results of a prospective multicenter study of GETECCU (VACOVEII study)

BackgroundThe response to SARS-CoV-2 vaccination decreases in inflammatory bowel disease (IBD) patients, specially under anti-TNF treatment. However, data on medium-term effectiveness are limited, specially using new recommended seroconversion rate (>260BAU/mL). Our aim was to evaluate the 6-month>260 BAU-seroconversion rate after full vaccination and after booster-dose. MethodsVACOVEII is a Spanish multicenter, prospective study promoted by GETECCU. IBD patients full vaccinated against SARS-CoV-2 and without previous COVID-19 infection, treated or not with immunosuppressants, were included. The booster dose was administered 6 months after the full vaccination. Seroconversion was set at 260BAU/mL, according to most recent recommendations and was assessed 6 months after the full vaccination and 6 months after booster-dose. ResultsBetween October 2021 and March 2022, 313 patients were included (124 no treatment or mesalazine; 55 immunomodulators; 87 anti-TNF; 19 anti-integrin; and 28 ustekinumab). Most patients received mRNA-vaccines (86%). Six months after full vaccination, overall seroconversion rate was 44.1%, being significantly lower among patients on anti-TNF (19.5%, p<0.001) and ustekinumab (35.7%, p=0.031). The seroconversion rate after booster was 92%. Again, anti-TNF patients had a significantly lower seroconversion rate (67%, p<0.001). mRNA-vaccine improved seroconversion rate (OR 11.720 [95% CI 2.26–60.512]). ConclusionThe full vaccination regimen achieves suboptimal response in IBD patients, specially among those anti-TNF or ustekinumab. The booster dose improves seroconversion rate in all patients, although it remains limited in those treated with anti-TNF. These results reinforce the need to prioritize future booster doses in patients on immunosuppressants therapy, specially under anti-TNF, and using mRNA-vaccines.

Assessment of post-COVID-19 vaccination neutralizing antibodies in kidney transplant and hemodialysis patients versus the general population

Background Patients receiving hemodialysis (HD) and kidney transplant recipients are immunocompromised populations prioritized for coronavirus disease 2019 (COVID-19) vaccination, however, there were few clinical trials with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccine responses. Compared with controls, individuals with chronic kidney disease and those on immunosuppressants have lower antibody titers and rates of seroconversion after vaccination. There is a lack of data on their humoral response to COVID-19 immunization. To study the effect of different types of available COVID-19 vaccines in Egypt (AstraZeneca, Sinopharm, Pfizer/BioNTech, and Sputnik) on neutralizing antibodies against COVID-19 in HD and kidney transplantation patients compared with the healthy population. Patients and methods A total of 84 participants; 28 HD patients, 28 kidney transplant recipients, and 28 healthy medical staff members were recruited to test the serological reaction. Six months following the second dose of the COVID-19 vaccine, we evaluated antibody titers against SARS-CoV-2 by Elecsys Anti-SARS-CoV-2 S (Roch) and collected data from the patients, including their comorbidities and the length of time since their kidney transplant. Results All the study groups were comparable as regards age, sex, and BMI, however, hemoglobin was significantly higher in the control group. Antibody response to vaccination was strongest in the control group (100%), followed by HD patients (85%), with transplant recipients showing a significantly weaker response (60%). The Pfizer vaccine generated higher neutralizing antibody levels compared with other vaccines in this study. Yet, the difference was not statistically significant. Additionally, no significant difference in response between the different vaccine types. the transplant group displayed significantly lower levels compared with the control group (P&lt;0.001) and a trend towards lower levels compared with the dialysis group (P=0.06). Conclusion Our study found that all tested vaccines generated comparable levels of neutralizing antibodies in healthy individuals and those with chronic kidney disease (dialysis patients). While 85% of dialysis patients achieved seroconversion (positive antibody test) similar to the healthy control group, only 60% of kidney transplant recipients did. the duration post-transplant may be associated with higher rate of seroconversion. the transplant group displayed lower levels of antibodies compared with the control and the dialysis group which suggests a weaker immune response in transplant patients.

Effectiveness of zero dose HBV vaccine on prevention of HBV breakthrough infection among vaccinated Egyptian children

Hepatitis B virus (HBV) is a vaccine preventable disease. Sufficient post vaccination response is critical step to achieve infection eradication. Vaccine hypo-responsiveness is a major risk factor for HBV chronic infection. We aimed to evaluate the effectiveness of birth dose HBV vaccine in preventing perinatal HBV infection and to detect the rate of HBV surface antibody (HBs-Ab) seroconversion and its relation to interleukin-4 polymorphism (IL-4 PM) among a group of vaccinated Egyptian infants. This observational analytical study involved 77 infants aged 6 to 12 months who received 4 doses of HBV vaccine including a zero dose. We measured serum levels of HBV-DNA and hepatitis B surface antigen (HBsAg) as markers of infectivity, and the level of (HBsAb) to assess vaccine responsiveness. Cytokine gene analysis to detect IL-4 gene polymorphism and its association with vaccine un-responsiveness were investigated. We observed that none of the vaccinated infants acquired HBV infection. Of the included 77 infants, seroconversion against HBV was detected in 72 (93.5%), 28 (36.4%) had low response and 44 (57.1%) had high response. While 5 (6.5%) were non responders. There was significant association between IL-4 gene polymorphism and the poor seroconversion after HBV vaccination. (p=0.03). Furthermore, HBsAb titer was significantly lower in children who have IL-4 gene polymorphism (p=0.014). In conclusion, implementation of birth-dose HBV vaccination is effective for prevention of perinatal infection, but seroconversion rate may be insufficient to induce long term protection. IL-4 gene polymorphism is associated with poor response to HBV vaccine.

Safety, immunogenicity, and optimal dosing of a modified vaccinia Ankara-based vaccine against MERS-CoV in healthy adults: a phase 1b, double-blind, randomised placebo-controlled clinical trial.

MERS-CoV is a respiratory pathogen with a case-fatality rate of 36%, and for which no vaccines are currently licensed. MVA-MERS-S is a candidate vaccine based on recombinant modified vaccinia virus Ankara (MVA). In this study, the safety, immunogenicity, and optimal dose schedule of MVA-MERS-S was assessed in individuals with previous exposure to SARS-CoV-2 infections and vaccines. We conducted a multicentre, double-blind, randomised controlled phase 1b clinical trial at two university medical centres in Germany and the Netherlands. Healthy volunteers aged 18-55 years were assigned by computer randomisation to receive three intramuscular injections of 107 or 108 plaque-forming units (PFU) of MVA-MERS-S, with two treatment groups each of either 28-day or 56-day intervals between the initial two doses, and one control arm that received only placebo, at a ratio of 2:2:2:2:1. The third dose was given after 224 days. The sponsor, clinical and laboratory staff, and participants were masked to both vaccine dose and dosing interval. The primary outcome was safety, assessed in the all participants who had received at least one injection; daily solicited vaccine reactions were recorded after each dose for 7 days, unsolicited adverse events for 28 days, and serious adverse events throughout the study. The secondary outcome was humoral immunogenicity, measured with vaccine-induced geometric mean antibody concentrations and seroconversion rates, analysed in all participants who received at least three allocated treatments. This study is registered at ClinicalTrials.gov (NCT04119440) and is completed. Between 26 July, 2021, and 3 March, 2022, 244 volunteers were screened, 177 of whom were eligible and 140 were randomly assigned either to the 28-day 107 PFU group (n=32), 56-day 107 PFU group (n=31), 28-day 108 PFU group (n=31), 56-day 108 PFU group (n=30), or placebo group (n=16). In total, 178 doses were administered of 107 PFU of MVA-MERS-S, 174 of 108 PFU, and 164 doses of placebo, and 139 participants received at least one injection. 73 (53%) were female and 66 (48%) were male. No serious vaccine-related adverse events occurred. Solicited local reactions were mild in 288 (93%, 95% CI 90-96) of 309 reports and consisted primarily of pain or tenderness. Pain or tenderness (of any severity) occurred after 69 (39%, 32-46) of 178 107 PFU injections, 138 (79%; 73-85) of 174 108 PFU injections, and 18 (11%; 7-11) of 164 placebo injections. Of 595 reported solicited systemic reactions, 479 (81%, 77-83) were graded as mild. Systemic reactions of any grade occurred after 77 (43%; 36-51) 107 PFU injections, 102 (59%; 51-66) 108 PFU injections, and 67 (41%; 34-49) of 164 placebo injections. At 28 days after the second dose, MERS-CoV neutralising antibodies were highest for participants assigned to 56-day 108 PFU, with geometric mean ratios of 7·2 (95% CI 3·9-13·3) for the 56-day 108 PFU group versus the 28-day 108 PFU group (p<0·0001), 3·9 (2·1-7·2) for the 56-day 108 PFU group versus the 56-day 107 PFU group (p=0·0031), and 5·4 (2·9-10·0) for the 56-day 108 PFU group versus the 28-day 107 PFU group (p=0·0003). MVA-MERS-S was safe and immunogenic in individuals with previous and concurrent SARS-CoV-2 exposure. The second vaccination with the 108 PFU dose of MVA-MERS-S elicited a stronger humoral immune response when administered 56 days after the first dose than a 28-day interval. Further studies are needed to verify these findings in groups at risk for MERS-CoV exposure, and at risk of severe disease, including older individuals and those with relevant comorbidities. Coalition for Epidemic Preparedness Innovations, the German Centre for Infection Research, and the German Research Foundation.

A 50-year-old question: Can imidocarb chemoprophylaxis ensure seroconversion for babesiosis in cattle under field conditions?

Bovine babesiosis, caused by Babesia bovis or Babesia bigemina, is a major tick-borne disease affecting livestock. In regions with limited vaccine availability, imidocarb is widely used as a chemoprophylactic drug. Although it is assumed that chemoprophylaxis allows for the development of immunity shortly after treatment, the extent of seroconversion during the imidocarb administration protocol remains largely unexplored, with most investigations emphasizing symptom prevention. This research endeavors to verify the seroconversion rate (humoral immunity) of cattle undergoing imidocarb chemoprophylaxis while exposed to tick vectors in field conditions. Fifteen tick-naïve heifers were used, with twelve receiving imidocarb (experimental group) on day 0 of the experiment, and the remaining three serving as controls. On day one of the study, all animals were introduced into a tick-infested pasture. Subsequently, at 28-day intervals (days 28, 56, 84, 112, 140, and 168), the experimental group received imidocarb treatments (1.2 mg/Kg). The detection of antibodies against B. bovis and B. bigemina was performed using commercial ELISA kits. Throughout the study, all animals were exposed to natural infestation by Rhipicephalus microplus ticks. By the 56th day, after two imidocarb doses, 25 % of the experimental group had seroconverted for B. bovis, and 41 % for B. bigemina. By the 84th day, 66 % were seropositive for B. bovis and B. bigemina. By the 112th day, 75 % were seropositive for B. bovis. Notably, one heifer (8 %) failed to seroconvert for either species, while 41 % remained seropositive for only one Babesia species. These findings underscore certain limitations of the chemoprophylaxis protocol for bovine babesiosis. While the majority of treated cattle become seropositive for at least one Babesia species after four successive treatments, exposure to the parasite while receiving imidocarb chemoprophylaxis does not guarantee seroconversion for all treated animals.

Effects of age and gender on immunogenicity and reactogenicity of SpikoGen recombinant spike protein vaccine: a post-hoc analysis

SpikoGen® COVID-19 vaccine is based on the spike protein extracellular domain of the ancestral Wuhan-Hu-1 strain modified by removal of the furin cleavage site and addition of stabilising mutations expressed as a recombinant protein in insect cells. It is formulated with Advax-CpG55.2™ adjuvant to ensure optimal immunogenicity. In this study, data from several SpikoGen® clinical trials was retrospectively analysed to assess for any effect of gender or age on seroconversion, neutralizing antibody levels or the incidence of adverse events. Following the 1st dose, older age was associated with a reduced rate of fatigue (RR 0.97, p < 0.001), headache (RR 0.98, p = 0.034) and myalgia (RR 0.97, p=0.016), following the 2nd dose, the rate of fatigue (RR 0.98, p = 0.017) but following the 3rd dose no effect of age on adverse events was evident. Similarly, following the 1st dose, men reported a 19% lower incidence of fatigue, 36% lower incidence of headache and 28% lower incidence of myalgia when compared to women. Interestingly, there was no relationship between age or gender and serum neutralizing antibody levels, although after each vaccine dose there was a consistent trend to women having a higher seroconversion rate. There was no correlation between neutralizing antibody levels and adverse events. Unlike what is seen with mRNA vaccines, reactogenicity trended lower after each subsequent SpikoGen® dose. Overall, SpikoGen® exhibited positive immunogenicity and low reactogenicity, indicating that a low incidence of adverse events does not equate to poor immunogenicity. SpikoGen® remains a promising protein-based vaccine platform for COVID-19 protection.