Post Vaccination Research Articles (Page 1)

SARS-CoV-2 transmission in Malawi remains unclear due to high proportions of mild/asymptomatic infections and limited diagnostics. Existing seroprevalence studies in Malawi have primarily used convenience samples and enzyme-linked immunosorbent assays (ELISAs). We assessed SARS-CoV-2 neutralisation in a longitudinal Malawian population-based cohort, assessing protective immunity post-infection and vaccination. Sera were obtained from rural (Karonga, n = 958) and urban (Lilongwe, n = 918) based participants at three-monthly intervals (February 2021-April 2022). Neutralising antibodies against SARS-CoV-2 were measured using human immunodeficiency (HIV)-based pseudotype assays in HIV-uninfected participants, and vesicular stomatitis virus-based assays in HIV-infected participants and an HIV-uninfected subset. Nucleocapsid ELISAs identified vaccinated participants also infected. SARS-CoV-2 neutralisation profiles increased in complexity over time from rising vaccination coverage and emerging variants. Neutralising antibody prevalence was higher in Lilongwe than Karonga (68.1% (CI 63.5-72.4) vs. 45.4% (CI 41.6-49.3), Survey 4). Hybrid immune and solely vaccinated participants exhibited higher titres than those solely infected. Children < 15 years had the lowest neutralising antibody titres among infected (not vaccinated) participants. People living with HIV had lower neutralising responses than those HIV-uninfected, particularly post vaccination. We therefore recommend surveillance of children and people living with HIV as low neutralisation responses increase reinfection risk. COVID-19 vaccination should be prioritised for HIV-infected individuals.

SARS-CoV-2-Specific Immune Responses to Vaccination in Children and Adolescents with Suppressed Immune Systems: A Prospective, Observational Study.

Background/Objectives: FLU-v is a peptide-based broad-spectrum influenza vaccine proven to induce humoral and cellular immune responses in humans. In this study, FLU-v-specific IgG1 and IgG3 subclass antibodies, induced by adjuvanted or non-adjuvanted FLU-v vaccination in healthy adults participating in a phase II clinical study, were quantitated. The ability of these antibodies to induce NK cell activation was investigated. Methods: An ELISA was developed to quantify FLU-v-specific IgG1 and IgG3 antibodies in serum. A flowcytometric assay based on an NK cell line was used to evaluate NK cell activation by expression of degranulation marker CD107a. Results: In the adjuvanted FLU-v group, IgG1 and IgG3 seroconversion on day 42 was 88.5% and 86.5% compared to 53.4% and 29.3% in the non-adjuvanted FLU-v group, which was significantly different from the respective placebo groups (0–6.3%). Adjuvanted FLU-v vaccination induced a raise in median IgG1 and IgG3 levels from 435 and 167 ng/mL pre vaccination to 4422 and 2020 ng/mL 42 days post vaccination, representing a fold increase of 16.3 for IgG1 and 11.6 for IgG3, which was sustained on day 180 post vaccination (10.4-fold and 5.0-fold, respectively). Non-adjuvanted vaccination induced a more modest increase in IgG1 and IgG3 from 655 and 206 ng/mL pre vaccination to 1808 and 264 ng/mL 42 days post vaccination. A correlation between levels of FLU-v-specific IgG, IgG1, or IgG3 and their ability to induce NK cell activation was demonstrated. Conclusions: A single dose of adjuvanted FLU-v induced high levels of long-lasting antigen-specific IgG1 and IgG3 antibodies with NK cell-mediated effector functions relevant to protection against influenza disease.

BackgroundGliomas are the most common primary brain malignancy in adults, with treatment advances limited by challenges like the blood-brain barrier, tumour heterogeneity, and an immunosuppressive microenvironment. Tumour vaccines, such as adenoviral vector and mRNA-based vaccines, may overcome these barriers, but the ability of glioma patients to mount an immune response to these therapies remains unclear. This study assesses immune responses to adenoviral DNA and mRNA-based COVID-19 vaccinations in a glioma-enriched population as a model for glioma-based vaccine therapies.MethodsCOVID-19 naïve glioma and non-glioma solid tumour patients, along with healthy volunteers, were recruited between May 2021 and December 2022. Blood samples were collected at various time points: pre-vaccination, between the first and second doses, and at 1-, 3-, and 4-6-months post 2nd vaccination, including after a third booster dose. SARS-CoV-2 specific immune responses were evaluated using ELISA and ELISPOT assays.ResultsA total of 91 participants were analysed. At 1-month post 2nd vaccination, no significant differences in seroconversion rates were observed. By 3 months, glioma and non-glioma patients had significantly lower rates compared to healthy volunteers. Memory B and T cell responses were similar between glioma patients and healthy volunteers, but non-glioma patients showed decreased responses. Vaccine efficacy was comparable across all cohorts.ConclusionThis study demonstrates that glioma patients can mount meaningful immune responses to DNA and mRNA vaccines, suggesting that glioma-based vaccine therapies are feasible and warrant further exploration.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11060-025-05258-9.

While rabies has not been reported in northern sea otters (Enydra lutris kenyoni), it is an infection with severe implications. The World Organization for Animal Health considers a serum titer of at least 0.5 IU/ml as adequate when importing vaccinated domesticated animals into rabies-free areas, a standard often used for zoological species. A few facilities have vaccinated sea otters against rabies, but titers were not analyzed. Production of serum neutralizing antibodies to rabies was evaluated following vaccination of 15 northern sea otters from the Alaska SeaLife Center and the Minnesota Zoo using the rapid fluorescent focus inhibition test. No animals had measurable titers prior to vaccination, and all 15 animals demonstrated antibody production post-vaccination. Titers were evaluated at different intervals (30-834 days) post-vaccination and were found at or above 0.5 IU/ml in 10/10 otters at approximately one month, 3/3 at two months, 6/7 at three months, 1/2 at five months, and 2/6 at 6-13 months. Three animals received a booster vaccination one year post initial vaccination, resulting in increased titers in all three one year later. No adverse reactions to vaccination were noted. If the prevailing epidemiological landscape deems rabies to be a concern, booster vaccinations could be considered after 3-4 months to increase the likelihood of adequate protection.

SARS-CoV-2 spike antibody and T cell response in MS patients on high efficacy therapies post vaccine.

Diarrhea is the passage of excessively liquid or frequent stools with increased water content. Acute diarrhea is defined as the abrupt onset of 3 or more loose stools per day and lasts no longer than 14 days. The most common causes of acute diarrhea in children are viral infection, rotaviruses the most common. Although often considered a benign disease, acute gastroenteritis is a major cause of morbidity and mortality in children around the world, responsible for 1.34 million deaths annually in children younger than 5 years, which account for 15% of all child deaths. The introduction and free access of Rotarix since 2019 in Albania had an enormous impact in morbidity and hospitalization due to gastroenteritis in children.

Rabies is a zoonotic disease with virtually 100% case fatality rate but preventable with early administration of post exposure prophylaxes rabies vaccine to the bite victim. The objectives of this study were to assess the awareness on rabies, modes of transmission, preventive measures, and their rate of exposure to dog bites among dog handlers. The work was carried out in five Local government areas of Gombe State. Ninety-one structured questionnaire was administered by face-to-face interviews in the commonly spoken local dialect (Hausa) to dog handlers. The questionnaire covered information on demographic characteristics, awareness toward rabies and their rate of exposure to dog bites. Only 28 (30.8%) of the respondents were informed that rabies could be fatal; 56 (61.5%) respondents were aware that dog handlers faced risks of rabies infection. Of the participants, eighty-seven (95.6%) recognized that dog bites are responsible for the transmission of rabies; nonetheless, 42 (46.2%) had experienced cuts, and 38 (41.8%) had been splashed with nerves/blood during the processing of raw dog meat. Only 13 respondents (14.3%) were aware of the appropriate management for dog bite wounds in the most severe circumstances. Sixty responders (67.8%) were bitten by dogs, although none received post-exposure vaccination. Approximately 89.3% of the respondents favored the non-conventional way for treating dog bite wounds. Therefore, knowledge on the possible risk of exposure, dog bite wound treatment, post exposure rabies vaccination and preventive measures of rabies need to be improved. An adequate awareness of rabies is very crucial in controlling

BackgroundSafe and effective vaccines are a key preventative measure to protect infants from SARS-CoV-2 infection and disease. Although mRNA vaccines induce robust antibody titers in infants, little is known about the quality of CD4 T-cell responses induced by vaccination. CD4 T-cell responses are important in orchestrating coordinated immune responses during infection and may help to limit disease severity.MethodsTo characterize the CD4 T-cell response to SARS-CoV-2 mRNA vaccination in infants, we sampled blood from 13 infants before and after primary SARS-CoV-2 mRNA vaccine series; samples from 12 historical vaccinated adults were used for comparisons. Peripheral blood mononuclear cells were stimulated with spike peptide pools, and the ability of CD4 T-cells to secrete Th1, Th2, and Th17 cytokines was quantified. Measures of polyfunctionality were generated with the COMPASS algorithm.ResultsWe observed a significant increase in CD4 T-cells producing IL-2 (0.01% vs 0.08%, P = .04) and TNF-α (0.007% vs 0.07%, P = .007) following vaccination in infants but a more muted induction of IFN-γ production (0.01% vs 0.04%, P = .08). This contrasted with adults, in whom vaccination induced robust production of IFN-γ, IL-2, and TNF-α. Th2 and Th17 responses were limited in both infants and adults. In infants, CD4 T-cell responses post vaccination were greater in those who received mRNA-1273 vs BNT162b. In contrast to CD4 T-cell responses, spike-specific IgG titers were similar in infants and adults.ConclusionsThese data suggest that infants have restricted induction of cytokine-producing CD4 T-cells following SARS-CoV-2 mRNA vaccination relative to adults.

IntroductionVaccines remain the most effective preventive measure against the ever-changing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. However, vaccine access remains unequal, leaving healthcare workers in low- and middle-income countries (LMICs) like Ghana at increased risk, despite early prioritisation. These inequities threaten both individual safety and the resilience of health systems. Moreover, SARS-CoV-2 infections continue to occur, particularly with emerging variants, compounding these risks. This study aimed to investigate the incidence and risk factors associated with post-vaccination SARS-CoV-2 infections among healthcare workers at a tertiary hospital in Ghana following the administration of the ChAdOx1nCoV-19 vaccine.MethodWe conducted a prospective cohort study of 4252 healthcare workers aged 18 and above, who tested negative for the SARS-CoV-2, and partially or fully vaccinated with the ChAdOx1nCoV-19 vaccine at baseline. After completing the baseline questionnaire, healthcare workers were followed up for one year.Results2283 out of the 4252 (53.7%) healthcare workers had post-vaccination infections, with an overall incidence of 95.7 cases per 100 person-years (95% CI: 91.8–99.7) of follow-up. The incidence of breakthrough infection was 82.0 cases per 100 person-years (95% Cl 78.0–86.0). In a multivariable Cox regression, age, vaccination status, occupation, clinical stations, frontline status and previous SARS-CoV-2 infections were significantly associated with post-vaccination infections. Compared to non-clinical healthcare workers, nurses (HR = 1.91, 95% CI: 1.69–2.17) and doctors (HR = 1.37, 95% CI: 1.24–1.73) had a higher risk of post-vaccination infections. Similarly, elderly individuals (HR = 1.04, 95% CI: 1.02–1.05) and those with comorbidities (HR = 1.86, 95% CI: 1.67–1.73) were more likely to develop post-vaccination infections. Frontline healthcare workers and healthcare workers stationed at the point-of-entry services (emergency and outpatient clinics) had a high rate of infections. However, previous SARS-CoV-2 infections (HR = 0.80, 95% CI: 0.71–0.53) and full vaccination (HR = 0.56, 95% CI: 0.51–0.62) conferred some protection, despite an overall rise in infection post vaccination incidence.ConclusionIn conclusion, the results of our study suggest a high incidence of post-vaccination infections among healthcare workers in the context of varying epidemic waves. Additionally, the study identified partial or incomplete vaccination, elderly workers, comorbidities, frontline workers, nurses and point-of-entry service roles as high-risk factors for post-vaccination infections. These findings reinforce the need for tailored booster strategies and strengthened protection for high-risk healthcare workers in LMIC settings.

Thalassemia is a common hereditary hemoglobinopathy found largely in the "Thalassemia Belt". Thalassemia children are at risk of the hepatitis B virus (HBV) infection, given the frequent need for blood transfusions. The immune dysregulation underlying these diseases may lead to defective long-term protection even after full HBV vaccination. This study will evaluate the efficacy of an additional hepatitis B vaccine and will screen the influencing factors that affect immune responses of thalassemia children. All subjects were screened from August 2023 to July 2024 at Dr. Cipto Mangunkusumo Hospital, Jakarta, Indonesia, where 126 pediatric patients (3-18 years of age) were diagnosed with thalassemia. All the participants had previously received the Indonesian national hepatitis B vaccination program. Seventy two eligible children who exhibited negative immune protection against hepatitis B accordingly received a single booster dose of hepatitis B vaccine. One month later the immune response was assessed by determination of anti-HBs titers. Logistic regression was used to evaluate significant predictors of the anti-HBs titer. Age, gender, type of thalassemia, transfusion interval, ferritin levels, nutritional status, and splenectomy were compared with post vaccine anti-HBs levels. Following the booster, protective immunity was present in 75% of children and high protective titers were present in 50%. The predictors of post-booster anti-HBs level included age (OR = 0.5; CI = 0.2-0.8; p = 0.018) and splenectomy. Children with transfusion-dependent thalassemia, aged over 3 years, are recommended to receive a booster dose of the hepatitis B vaccine.

Background/Objectives: Toxoplasma gondii is a major cause of zoonotic infections in both humans and animals, resulting in significant mortality in susceptible species, such as New World primates and marsupials. Toxoplasmosis is particularly concerning in zoos and wildlife reserves, where outbreaks threaten conservation efforts for endangered species. In the absence of a commercially available vaccine against toxoplasmosis for humans and captive wild animals, current prevention strategies are limited to restricting the access of cats to enclosures, controlling rodent populations, and maintaining strict food hygiene. Recent research has shown promising results with an intranasal vaccine (VXN-Toxo) composed of maltodextrin nanoparticles conjugated with a purified, inactivated T. gondii parasite. This experimental vaccine does not pose a risk of causing disease and offers advantages such as better stability compared with live pathogen-based vaccines. Methods: This study presents a large-scale evaluation of the effect of VXN-Toxo administered to captive wildlife across 20 zoos in Europe and the Americas between 2017 and 2025. Seven hundred and eighty-four animals, representing over 58 species (including primates, marsupials, rodents, and felids), were vaccinated without any adverse events reported. Results: Retrospective mortality data from 20 participating zoological institutions revealed an overall 96.7% reduction—and, in many cases, a complete elimination—of toxoplasmosis-associated deaths post vaccination. Conclusions: These results demonstrate, for the first time, consistent and broad-spectrum protection against T. gondii of different strains in a wide array of captive wildlife species. This universal vaccine represents a promising tool for toxoplasmosis prevention in zoological collections, with significant implications for animal health and conservation strategies.

BackgroundRSV/ΔNS2/Δ1313/I1314L (RSVt) (Sanofi) is a candidate live-attenuated intranasal respiratory syncytial virus (RSV) vaccine for infants and toddlers.MethodsThis phase I/II randomized clinical trial, conducted at sites in the United States (N=22), Chile (N=2), and Honduras (N=2), enrolled participants 6–18 months of age in four cohorts. In cohort 4, the primary cohort reported in this article, participants were randomly assigned to receive vaccinations on days 0 and 56 of either low-dose (LD) RSVt, high-dose (HD) RSVt, or placebo. Primary safety end points included: unsolicited systemic adverse events 30 minutes post vaccination, and solicited site and systemic reactions 28 days post vaccination. The primary immunogenicity end points were the geometric mean titers of RSV A serum neutralizing antibody after vaccinations 1 (day 56) and 2 (day 84) among RSV-naive participants at baseline.ResultsAmong 180 participants (LD, N=61; HD, N=58; placebo, N=61), 115 were RSV-naive at baseline (LD, N=45; HD, N=32; placebo, N=38). No unsolicited systemic adverse events occurred within 30 minutes post vaccination in the LD or HD groups. Solicited site reactions were reported by 83.1%, 74.5%, and 68.9% of participants post vaccination 1, and 75.6%, 77.8%, and 55.6% post vaccination 2, in the LD, HD, and placebo groups, respectively. Solicited systemic reactions were reported by 79.7%, 73.2%, and 77.0% of participants post vaccination 1, and 66.7%, 66.7%, and 48.1% post vaccination 2, in the LD, HD, and placebo groups, respectively. Neutralizing antibody titers among RSV-naive participants were 83.7 (95% confidence interval (CI), 49.5 to 142.0), 79.4 (95% CI, 47.2 to 134.0), and 20.6 (95% CI, 16.4 to 25.9) post vaccination 1, and 142.0 (95% CI, 86.4 to 232.2), 107.0 (95% CI, 70.0 to 163.0), and 26.3 (95% CI, 18.8 to 37.0) post vaccination 2, in the LD, HD, and placebo groups, respectively.ConclusionsThe RSVt vaccine demonstrated promising immunogenicity profiles at both LD and HD strengths among infants and toddlers, without identified safety concerns. (Funded by Sanofi; ClinicalTrials.gov number, NCT04491877).

Validating community concerns of menstrual changes associated with COVID-19 vaccination using a self-controlled case series analysis of real-world data.

The ongoing COVID-19 pandemic caused by SARS-CoV-2 remains a critical global health priority, with persistent socioeconomic ramifications despite its reclassification from Public Health Emergency of International Concern (PHEIC) status. While humanized major histocompatibility complex (hMHC) murine models have been extensively utilized in oncological research, their application in virological studies-particularly for coronavirus pathogenesis-remains underexplored. This study systematically characterized immune responses in SARS-CoV-2-challenged hMHC mice lung tissues through comparative transcriptomic profiling, combined with functional enrichment and PPI network analyses. Key findings demonstrate that hMHC mice exhibit enhanced immunological activation relative to wild-type controls, particularly in IFN-γ signaling pathways and neutrophil mobilization dynamics that closely parallel human post-vaccination responses. Comparative analysis with human whole blood RNA-seq datasets revealed that hMHC mice exhibit both high reproducibility in transcriptomic profiles and significant similarity to human immune responses across innate and adaptive immunity. These results confirm that the hMHC murine model can serve as an effective platform for vaccine research, providing a theoretical foundation for the application of humanized MHC mice and offering new insights into viral infection mechanisms and the development of novel vaccines.

Infertility was often considered a female issue, but male infertility emerged significantly after the COVID-19 pandemic. Hence, assessments are crucial for planning policies on health care and family planning and reasons thereof post vaccinations. The present study was a case-control, dual-centers, prospective study with normal sperm parameters. Semen samples collected by masturbation for idiopathic reasons were conducted at King Abdulaziz University with 133 samples, followed by molecular modeling via interaction between IZUMO1, Alpha2A adrenergic receptor, and Fibroblast growth factor receptor 2 protein with IgA antibody produced post vaccination/infection. The infertile males under 30 (21%), 31-40 (50%), 41-50 (24%) and over 50 (5%), with altered sperm motility grades are A (8.45%), B (11.1%), C (15.8%), and D (59.8%) were reported. Liquefaction times range from 36 to 30 minutes by age, with abnormal sperm percentages between 43.85% and 46.33%. Protein molecular interaction between IZUMO1, Alpha2A adrenergic receptor, and Fibroblast growth factor receptor 2 protein with IgA antibody shows cumulative length of 25.354 Å, 39.049 Å, and 41.999 Å, respectively, with significant interaction between atoms chain, amino acid, marked variation in bond length. Male infertility peaks at 31-40 years, with lowering in men aged 41-50 years, IgA antibody reduced sperm motility, causing immunogenic infertility exacerbated post-COVID-19 vaccination or infection. Interaction of IgA and various receptors produced stable interactive molecules of IgA and proteins on sperm, affecting motility, aliquefication, and abnormal sperm percentage disturbing the normal dynamics of sperm cells opening a new dimension of infertility among males.

Adverse drug reactions following SARS-CoV-2 vaccination of 3805 healthcare workers cause substantial sick-leave and are correlated to vaccine regimen, age, sex and serological response.

Background: Tuberculosis continues to be one of the major causes of morbidity and a leading cause of mortality worldwide, especially in low- and middle-income countries like Nigeria. To effectively contribute to the fight against tuberculosis (TB), mothers must be well-informed about TB and how to prevent TB in children. The objective of this study was to evaluate the knowledge and perception of mothers about Bacillus Calmette-Guérin (BCG) scarring. Methods: This was a cross-sectional descriptive study performed from July to December 2024 in a tertiary health care facility in Yola, Nigeria. Results: Majority (80%) of the caregivers were aware that BCG protects against tuberculosis, about 95% believed BCG can result in scar formation and 61% agree that presence of scar indicates that BCG vaccine is working. About 90% of the caregivers would report to a health facility when the scar fails to appear after BCG vaccination. Conclusions: Majority of the caregivers (mothers) were found to be aware that BCG protects against TB and accept BCG scarring following vaccination. We recommend regular health education to mothers during routine immunization to maintain adequate and accurate health information on vaccines.

This report presents two cases of herpes simplex keratitis recurrence after COVID-19 mRNA vaccination in patients on herpetic prophylaxis due to recurrent herpetic keratitis. A 58-year-old man with a history of a previous penetrating keratoplasty presented with blurred vision and evidence of corneal endothelitis 48 h after the first dose of the m-RNA vaccination, and a 24-year-old male student came with a dendritic ulcer 72 h post first vaccination dose. The original prophylactic treatment of 400 mg of acyclovir twice daily was increased to five times per day for a week for both patients. The grafted patient additionally received an increase in Dexamethasone 0.1% from twice daily to four times a day. Improvement was noted within two days and documented at the weekly review, during which both patients returned to their prophylactic antiviral regime without further recurrence. At the time of their second dose of vaccination, both patients followed the same regime with an increase in treatment as per the first dose of vaccination without recurrence. Our findings suggest that patients with recurrent herpetic disease receiving prophylactic treatment need close monitoring when experiencing even subtle symptoms of recurrence and may benefit from an increase in their dose to therapeutic levels during the first days after the COVID-19 mRNA vaccination.

BACKGROUNDInfluenza B virus is a significant contributor to annual total and severe cases of influenza, particularly in the young and elderly. Coupling whole virus genome sequencing with the monitoring of influenza cases allows for the identification of increased disease burden and the emergence of novel virus variants.METHODSInfluenza B virus infected individuals were identified in the Johns Hopkins Health Systems network and whole IBV genome sequencing was performed. Phylogenetic analysis and sequence alignments were used to identify the IBV clades and novel virus mutations. The amount of neutralizing antibody activity specific to different IBV clades was measured.RESULTSLate in the 2024-25 Northern Hemisphere influenza season, a surge of IBV cases were identified. The IBV responsible for the surge, C.3re, was a clade C.3 virus that had reassorted with clade C.5.1 viruses and acquired a mutation predicted to mask a key neutralizing antibody epitope on the hemagglutinin protein. The neuramindase gene contained mutations predicted to reduce neutralizing antibody binding and potentially alter oseltamivir sensitivity. The C.3re viruses preferentially infected children but showed no significant increase in disease severity. The C.3re viruses were poorly neutralized by pre and post influenza vaccination serum.CONCLUSIONSThe C.3re IBV genotype that emerged in late in the 2024-25 influenza season is antigenically mismatched with current circulating IBVs and the IBV vaccine strains chosen for the 2025 Southern Hemisphere and 2024-25 Northern Hemisphere season. This may result in lower vaccine efficacy increases in IBV cases in upcoming influenza seasons.