Vaccines

Background: Indonesia launched a nationwide school-based HPV immunization program in August 2023. Despite this, regional disparities in vaccine uptake persist. Therefore, we undertook a study in North Sumatra Province to assess HPV vaccination coverage and analyze the main factors affecting the uptake of HPV vaccination. Methods: This study employed a mixed-methods approach and was carried out in Medan and Deli Serdang of North Sumatra Province. Quantitative data were used to examine HPV coverage rates among school-aged girls in 2024, while qualitative interviews with parents, teachers, and health officers explored administrative, social, and behavioral barriers and facilitators. Results: In 2024, HPV vaccine coverage in Deli Serdang reached 62.09%, while Kota Medan lagged behind at just 27.20%. High-coverage schools in the Galang subdistrict benefited from proactive engagement between Puskesmas (community health clinics) and parents. In contrast, lower-coverage areas experienced logistical and communication challenges. Parents expressed a preference for face-to-face communication over written consent forms and emphasized the importance of clear, empathetic messaging. Conclusions: The stark contrast in coverage—particularly the low uptake in urban Kota Medan—highlights the need for more responsive and localized implementation strategies. Strengthening direct communication, addressing administrative inefficiencies, and fostering trust through tailored community engagement are critical. These findings suggest a need for targeted improvements in urban settings and further research across diverse regions to inform policy development and strategies for improved coverage of HPV vaccinations. Full article

Background: Trust in information sources is essential to enhance an individual’s understanding of the message and boost their willingness to change or act on specific health behavior, including vaccine uptake. This study explores the association between trust in information sources and parents’ knowledge, attitudes, and practices regarding their children’s 13-valent pneumococcal conjugate vaccine (PCV13) uptake across seven cities in the Yangtze River Delta (YRD) region in China. Methods: A cross-sectional web-based survey was conducted from May to June 2023. Adult parents (N = 1304) who had at least one child aged 24 months or less and lived in the YRD region were recruited. The Adjusted Ordinary Least Squares (OLSs) regression model was applied to estimate the association between participants’ level of trust in different information sources and their knowledge, attitudes, and practices of children’s PCV13 vaccination. Results: Information from the Disease Control and Prevention Center (CDC) source received the highest trust score. Age, gender, education, and annual household income were related to varied trust levels in specific sources. Trust in the health service provider source was significantly associated with a better command of PCV13 knowledge, acceptance of PCV13, and a higher likelihood of vaccination. Trust in online community sources was positively associated with vaccine uptake. Conclusions: The study participants highly trusted information from health service provider sources. These sources may be effective channels with potential to enhance parents’ vaccine knowledge and acceptance of PCV13. Public health workers could utilize trusted sources to disseminate the benefits of the PCV13 and encourage the uptake of the vaccine. Full article

Background: Bacterial Chondronecrosis with Osteomyelitis (BCO) is a significant issue affecting the welfare and economy of the broiler industry, causing substantial revenue losses annually. This disease is frequently associated with Staphylococcus spp. and Enterococcus spp. infections and necrosis of leg and vertebral bones. The typical annual lameness incidence of approximately 3–5% may increase to 30% during outbreaks. Neither the etiology or pathogenesis of the disease has been comprehended, nor have effective preventative measures been identified. Electron beam (eBeam) technology is renowned for producing efficient whole-cell vaccines by preventing bacterial multiplication through irreversible DNA shredding while preserving the integrity of membrane proteins (immunogenic epitopes). This study aims to reduce BCO-induced lameness in broiler chickens via in ovo immunization using eBeam-inactivated multi-strain Staphylococcus. Methods: A total 1080 birds were assigned to four vaccination groups: eBeam-inactivated, formalin-inactivated, combination of eBeam- and formalin-inactivated, and sham (vehicle). The birds were directly exposed to aerosolized, natural BCO challenge until 56 days of age. Results: Birds vaccinated with the eBeam-inactivated Staphylococcus vaccine showed a significant reduction (>50%) in daily cumulative lameness compared to other groups and a decrease in Staphylococcus colonization was observed in the leg joints of treated birds. Conclusions: the eBeam-inactivated Staphylococcus vaccine successfully prevented BCO lameness in broiler chickens. Full article

Background/Objectives: Meningococcal disease (MD) remains a significant public health concern worldwide. In Serbia, mandatory immunization against MD with the meningococcal polysaccharide vaccine (MenAC) for high-risk groups and international travelers was introduced in 2006. Since 2017, the polysaccharide vaccine has been replaced with the quadrivalent meningococcal conjugate vaccine (MenACWY). The aim of this study was to analyze long-term trends in incidence, age-specific patterns, seasonality, and lethality of invasive meningococcal disease (IMD) in the Autonomous Province of Vojvodina (AP Vojvodina), Serbia, over a 28-year period. Methods: A descriptive study analyzed all reported cases of IMD in AP Vojvodina, from 1997 to 2024. Data were obtained from the regional communicable disease surveillance system, based on mandatory hospital reporting and case classification according to national and WHO guidelines. Temporal, demographic, and clinical characteristics, along with disease outcomes, were analyzed. Results: From 1997 to 2024, 175 IMD cases were reported in AP Vojvodina. The annual incidence peaked in 1997 (1.24/100,000), with smaller surges in 2003 and 2005. Since 2006, coinciding with the introduction of immunization against MD, a sustained decline has been observed, with incidence rarely exceeding 0.30/100,000. A slight resurgence occurred in 2023–2024, with 13 cases reported. From 1997 to 2024, IMD in AP Vojvodina exhibited a clear seasonal pattern, with most cases occurring in winter and early spring, peaking in January (17%), March (12%), and February (11%), and the fewest cases occuring in the summer months. Throughout the study period, the highest IMD incidence rates were consistently observed among infants <1 year of age and children aged 1–4 years, with peaks of up to 22.9/100,000 and 16.0/100,000, respectively. Incidence was much lower in older age groups, especially adults. After a 2006 peak, rates declined across all ages, with a slight resurgence in 2023–2024 among children and adolescents. Children aged 1–4 years made up the largest share of IMD cases, peaking in January–March (45.1%). Half of the infant cases were recorded in October–November, while cases in older children, adolescents, and adults were fewer and showed varied monthly patterns, with small peaks in winter and early spring. During the 28-year study period, the highest IMD mortality rate was observed among infants <1 year of age (0.59 per 100,000 population), followed by children aged 1–4 years (0.32 per 100,000). Mortality rates declined progressively with increasing age, with the lowest rate recorded among individuals aged ≥40 years (0.01 per 100,000). Of the 175 IMD cases reported in AP Vojvodina (1997–2024), 21 were fatal (case fatality rate [CFR] = 12.0%). The CFR of IMD varied across age groups. The highest CFR was observed among individuals aged ≥40 years (21.4%), followed by the 5–9 years (17.4%) and <1 year (16.7%) age groups. None of the patients had been vaccinated against MD. Fatal outcomes were more common in children aged 1–4 years and among rural residents, though differences were not statistically significant (p > 0.05). Most deaths (57.1%) occurred in the first quarter of the year. A strong association was found between clinical form and outcome, with meningococcal sepsis being significantly more frequently associated with fatality than meningitis (p = 0.0002). Deaths were sporadic over time, with most occurring within 1–2 days of notification. All confirmed fatal cases were due to serogroup B. Conclusions: MD remains a rare yet serious public health threat in AP Vojvodina. Mortality rates indicate that the public health impact of this disease is greatest among the youngest age groups; however, the risk of death, i.e., disease severity, does not appear to be age dependent. The recent rise in cases, high fatality among sepsis patients, and absence of prior vaccination among all IMD cases highlight the need for enhanced surveillance, physician education, and consideration of introducing both MenACWY and MenB vaccines for high-risk groups. Full article

Background: The COVID-19 pandemic provided a unique opportunity to evaluate how the human immune system responded to a novel pathogen and to determine whether immune responses initiated through natural infection differ from those elicited by vaccination against the same antigen. Here, we provide a comprehensive analysis of SARS-CoV-2 Spike (S-antigen)-reactive memory B cells (B_mem) elicited in previously immunologically naïve subjects following their first infection with the original Wuhan-Hu-1 (WH1)-like strain or their initial COVID-19 mRNA prime-boost regimen encoding the same WH1-S-antigen. In particular, we tested the hypothesis that the primary encounter of SARS-CoV-2 S-antigen in lung mucosal tissues during infection vs. intramuscular COVID-19 mRNA injection would elicit different B_mem responses. Methods: Cryopreserved peripheral blood mononuclear cell (PBMC) samples collected following primary infection with the WH1 strain or completion of the initial prime-boost vaccination regimen were tested in ImmunoSpot^® assays to assess the frequency, Ig class/subclass usage, and cross-reactivity of the S-antigen-reactive B_mem compartment; pre-pandemic blood draws served as naïve controls. Results: The B_mem repertoires generated post-infection vs. post-vaccination were found to be quite similar but with some subtle differences. In both cases, the prevalent induction of IgG1-expressing B_mem in similar frequencies was seen, ~30% of which targeted the receptor binding domain (RBD) of the WH1-S-antigen. Also, the extent of cross-reactivity with the future Omicron (BA.1) RBD was found to be similar for both cohorts. However, IgA⁺ B_mem were preferentially induced after infection, while IgG4⁺ B_mem were detected only after vaccination. Conclusions: B_mem elicited in naïve human subjects following SARS-CoV-2 infection or after WH1-S encoding mRNA vaccination were only subtly different, although the relevance of these differences as it relates to immune protection warrants further investigation. Our findings serve to illustrate the usefulness and feasibility of performing comprehensive monitoring of antigen-specific B cell memory in larger cohorts using the ImmunoSpot^® technique. Full article

Background/Objectives: We previously demonstrated that dendritic cell (DC) expression of CXCR5 is required for T_H2 priming in mice infected with the helminth Heligmosomoides polygyrus (Hp). In this manuscript we examined how CXCR5 controls DC mediated CD4 T helper 2 cell (T_H2) development. Methods: We used in vitro T_H2 priming assays, RNA-seq analyses and in vivo Hp infection mouse models to identify roles for the CXCR5-expressing DCs in T_H2 development. Results: We showed that migratory conventional type 2 dendritic cells (cDC2) express CXCR5 and that deletion of Cxcr5 prevents migratory DC priming of T_H2 cells in vitro while overexpression of CXCR5 enhances migratory DC priming of T_H2 cells in vitro. To understand how CXCR5 facilitates the T_H2 priming capabilities of migratory cDC2 cells, we performed RNAseq analysis on wildtype and Cxcr5^−/− DC subsets isolated from msLN of Hp-infected mice. We observed that CXCR5 expression specifically by the migratory cDC2 subset promoted a pro-proliferative transcriptional program in cDC2 cells and was required for cDC2 cell accumulation in the msLN following Hp infection. We demonstrated that CXCR5 expression specifically by cDC2 cells was necessary for upregulation of Chitinase 3-like-1 (Chi3l1), which encodes a secreted protein (Chi3l1) that regulates allergic T_H2 responses. We showed that addition of recombinant Chi3l1 protein to in vitro T_H2 priming cultures enhanced T_H2 development and that deletion of Chi3l1 specifically in DCs resulted in fewer cDC2 cells and decreased T_H2 development in vivo following Hp infection. Conclusions: CXCR5 expressed by cDC2 cells is required for induction of Chi3l1, which in turn promotes the T_H2 priming capacity of these DCs. These findings provide insight into the actions of CXCR5 and Chi3l1 in helminth infection. Full article

Background/Objectives: Nocardia seriolae and Aeromonas veronii are two important pathogens that can affect a wide range of fish species and cause substantial economic losses. However, a vaccine that simultaneously protects fish from these two bacterial infections is not yet available. Methods: Three formalin-inactivated whole-cell vaccines prepared from N. seriolae and A. veronii (Monovalent Av, Monovalent Ns and Bivalent Av-Ns) were generated, and their efficacy was evaluated through a range of tests. The immune-related gene expression in the spleen and head kidney, enzyme activity, and specific antibody levels in serum were also detected. Results: All groups of vaccinated fish exhibited increased serum enzymatic activity compared with control fish, which peaked at week 3 after vaccination; in particular, that of the Bivalent Av-Ns group increased remarkably. The expression of immune-related genes in the spleen, head, and kidneys increased after immunization and were significantly enhanced (p < 0.05) in the bivalent vaccine group. Specific antibodies were produced at the 1st wpv, peaked at the 4th to the 5th wpv, and then decreased at the 6th wpv in all vaccinated groups. The Monovalent Av and Monovalent Ns against A. veronii and N. seriolae showed 56.67% and 22.22% RPS, respectively. Moreover, Bivalent Av-Ns offered 33.33% and 76.67% RPS for single infection with N. seriolae or A. veronii, as well as providing 44.44% RPS for dual infection with combined N. seriolae and A. veronii. Conclusions: Our findings indicate that the administration of the A. veronii and N. seriolae bivalent vaccine can protect largemouth bass from both bacterial infections. Full article

Introduction: Dengue virus (DENV) remains a global health threat, with four distinct serotypes (DENV1-4) that complicate vaccine development due to low-affinity, cross-reactive antibodies that increase the risk of antibody-dependent enhancement (ADE). Objective: To address the challenge of inducing strictly serotype-specific immune responses, this study explored the use of targeting individual lymph nodes (LNs) for the creation of simultaneous but independent immune responses as a targeted approach to reduce cross-reactivity and improve vaccine specificity. Methods: In the initial experiments, targeting individual LN successfully induced specific germinal centers (GCs) for different antigens in distinct LNs, highlighting its potential to enhance immune specificity. This approach was further tested using two virus-like particle (VLP)-based vaccines based on AP205 for DENV1 and DENV4, selected due to their genetic divergence and to probe the potential to minimize cross-reactive immune responses. In this setup, AP205-DV1 and AP205-DV4 were administered in targeted separate LNs, and the specificity of the immune response was compared to subcutaneous administration of a mixture of both vaccines. Results: Our data show that targeting distinct LNs elicited antibodies with significantly higher avidity, which is a critical factor in determining the neutralizing capacity of the immune response. Avidity measurements confirmed that this segregation approach results in a more refined selection of high-affinity B cells. Neutralization experiments demonstrated that targeting distinct LNs with individual vaccines induced a more potent and serotype-specific neutralizing response, compared to the injection of a vaccine mixture. Conclusions: These findings suggest that targeting individual LNs could be a promising method for enhancing both the specificity and potency of immune responses, particularly for flaviviruses. Targeting distinct LNs by direct administration of individual vaccines into distinct watersheds rather than individual lymph nodes will offer the opportunity to facilitate the approach in humans. Full article

Chronic viral infections and virus-induced cancers have been actively studied for decades, with many significant advancements in basic science, disease cure, treatment, and prevention. Yet, today, these infections and pathologies remain major contributors to morbidity and mortality worldwide. The international online conference “VIRCAN2024: Chronic viral infections and cancer, openings for Vaccines and Cure” aimed to address the remaining issues, present the research carried out in this broad field, and prognose directions for its development. The conference covered oncogenicity mechanisms and new approaches in the development of treatments and vaccines. VIRCAN2024 was held on the platform of Riga Stradins University, Riga, Latvia. The conference was supported by the Latvian Science Council grant “Human papillomavirus genome associated correlates of disease progression and treatment response for cervical neoplasms and cancer”, and the scientific journal Vaccines (MDPI). This report summarizes the lectures and presentations given at the conference. Full article

Background/Objectives: This study investigated susceptibility factors that may contribute to Post-Polio Syndrome (PPS) in elderly polio survivors. Methods: Serum immunoglobulin (Ig) levels, poliovirus neutralizing antibodies (PV NAb), and vitamin D status were evaluated in 80 PPS patients, 40 family members, and 89 healthy controls. Results: A significant number of PPS patients and their family members showed reduced levels of total IgG and/or IgA, and specific IgG subclasses, indicating a high prevalence of primary humoral immunodeficiencies within these groups. Despite these Ig deficits, PV NAb titers were similar across all groups, indicating high protection against poliovirus, likely due to vaccination campaigns with live virus in Italy and intense exposure to poliovirus, especially in long-term rehabilitation institutions. However, a small group of PPS subjects lacked neutralizing antibodies for specific poliovirus serotypes, suggesting more severe antibody deficiencies. Additionally, PPS subjects had a high prevalence of vitamin D deficiency, which likely increases their risk for osteoporosis/osteopenia and fractures. It is unclear if this deficiency was also present in their infancy, potentially enhancing their susceptibility to poliovirus. Conclusions: Overall, the findings indicate that genetic, immunological, or nutritional factors may increase individual susceptibility to the pathogenic effects of poliovirus. This study—limited to serum antibodies—highlights the complex relationship between immune status and long-term health in aging polio survivors. The results emphasize the need for potent poliovirus drugs and vaccines to help contain possible outbreaks but also—for poliomyelitis survivors—to avoid or mitigate the progression to PPS, the latest phase of this devastating disease. Full article

Background: Racial and ethnic differences in vaccine responses, particularly within Hispanic populations, remain underexplored. Disparities in immune function may be influenced by metabolic and inflammatory mechanisms. Methods: The current study investigated humoral immune responses to influenza vaccination in a diverse cohort of Hispanic individuals from South Florida, encompassing both White and Black Hispanics. Antibody responses were assessed post-vaccination, and B cell phenotypes were analyzed to evaluate inflammatory and metabolic characteristics. In vitro experiments were conducted to determine whether blocking metabolic pathways could alter the inflammatory phenotype of B cells. Data were analyzed using an unpaired Student’s t-test (two-tailed), and correlation analysis was conducted with Pearson correlation. Results: Our findings indicated that Black Hispanic individuals exhibited significantly reduced antibody responses compared to White Hispanics (p < 0.01) following influenza vaccination. This diminished humoral response correlated with inversely with serum LDH (r = −0.58; p = 0.0005) and other intrinsic inflammatory phenotypes in blood-derived B cells and was supported by changes in metabolic activity. In vitro blockade of metabolic pathways effectively reduced the inflammatory phenotype of B cells from Black Hispanic individuals, suggesting a mechanistic link between metabolic dysfunction and impaired vaccine-induced immunity. Conclusion: This study is the first to reveal racial disparities in influenza vaccine responses within a Hispanic population, highlighting reduced antibody production in Black Hispanics. These findings suggest that metabolically driven B cell inflammation may play a critical role and point to potential therapeutic strategies to address disparities in vaccine-induced immunity. Full article

Background/Objectives: The COVID-19 pandemic was characterized by the rapid transmission of the virus and a global race for vaccines, with vaccines such as AstraZeneca, CoronaVac, Pfizer, and Janssen arriving in Brazil in 2020. Concurrently, an infodemic of information, driven by the media and social media, highlighted the importance of health communication. This study examines how online newspapers in a Brazilian state disseminated information about vaccination and its relationship with vaccine adherence among the population. Methods: Quantitative research, in which a total of 5308 journalistic articles were verified, using two databases, one for the publication of journalistic articles and the other for vaccinations in the state, which applied 9,577,567 doses in the period. Results: The analyses demonstrated a positive correlation between the number of publications of articles and the number of applications of vaccines (rho = 0.407, p-value < 0.0005), revealing a relationship of both increase and decrease in the publication of newspaper articles and the application of vaccines in specific weeks during the analysis period. Vaccination data revealed low adherence to the booster dose by the population, with unequal values among the cities of the state. Conclusions: The study highlighted the potential importance of newspapers in disseminating information about vaccines during the pandemic, underscoring the need for regional health strategies to increase vaccination coverage. Full article

Background: Chronic illnesses pose a major global health challenge with an estimated 1.56 billion people affected worldwide in 2025, and 85% of these being older adults facing at least one chronic condition. These patients are particularly vulnerable to severe influenza complications and higher mortality rates due to weakened immune responses; in addition, vaccination rates in China remain significantly lower than those in developed nations. Methods: This review examines how chronic conditions exacerbate influenza-related effects through immune dysfunction and metabolic imbalances, and how influenza infection worsens chronic diseases by triggering inflammation, suppressing immunity, and causing secondary infections that lead to respiratory complications, cardiac complications, and blood sugar disturbances. Results: A bidirectional adverse interaction exists in which chronic illnesses increase influenza severity via poor immunity, while influenza accelerates chronic disease progression (e.g., cardiac events and diabetic ketoacidosis). Vaccination reduces hospitalization by 32–52% in patients with lung disease and mortality by 16–46% in diabetic patients, with good safety. Conclusions: The findings emphasize the urgent need for improved vaccination strategies in patients with chronic diseases. Such strategies are crucial to reducing disease burden, enhancing clinical outcomes, and improving quality of life, while also providing critical evidence for the development of public health policies. Full article

Background: COVID-19 vaccination and subsequent booster doses became critical components of public health strategies to control the pandemic and reduce disease severity, especially in fragile individuals. Among these, subjects undergoing dialysis represent one of the highly vulnerable populations. Methods: We conducted a multicenter case–control study among dialysis patients between March 2021 and May 2022 (study population n = 3264). We evaluated anti-S/RBD-IgG and anti-SARS-CoV-2 neutralizing antibodies before (T3) and after (T4) the third dose in individuals with a COVID-19 diagnosis after the third dose (cases) and in those who did not report infection (controls). Results: The study included 187 cases and 150 controls. Serological analysis showed a significant increase (p < 0.001) in anti-SARS-CoV-2 antibody levels after the third vaccine dose (from T3 to T4) in both groups. At T3, with the same number of days between the second dose and T3, the antibody levels detected were significantly lower in cases as compared to controls. At T4, we observed similar antibody titers in the two groups. Notably, the mean difference in time from the third dose to T4 was significantly greater in controls (73.0 days vs. 36.7, p < 0.001), suggesting a reduced antibody waning in controls. Accordingly, multivariate analysis showed that the risk of infection was considerably reduced by the pre-third-dose antibody levels. Conclusions: This study reinforces the critical role of the humoral response in preventing infections in the vulnerable population of dialysis patients. Regular monitoring of antibody levels and timely administration of booster doses are essential to optimize protection in this group. Full article

Background/Objectives: African swine fever (ASF) is a disease of domestic pigs and wild boar caused by African swine fever virus (ASFV), in which infection often leads to high morbidity and mortality. Although subunit and mRNA vaccines based on protective antigens have been explored for ASFV, their protective efficacy remains insufficient for practical ASF control, highlighting the need to identify new potential antigens capable of inducing more potent and broadly protective immune responses. Previously, we found that the antibodies against the ASFV E120R protein (pE120R) could significantly inhibit virus replication in primary porcine alveolar macrophages (PAMs). However, it is not yet known whether anti-pE120R antibodies can induce antibody-dependent cellular cytotoxicity (ADCC). Methods: In this study, we analyzed the conservation and immunogenic features of pE120R and established an HEK293T cell line with stable expression of pE120R as target cells (HEK293T-pE120R). Additionally, a co-culture system comprising target cells and peripheral blood mononuclear cells (PBMCs) was established to evaluate the ability of the anti-pE120R antibodies to induce ADCC as measured by lactate dehydrogenase (LDH) release assays. Results: The results showed that pE120R is highly conserved among different ASFV genotypes and contains multiple B-cell and T-cell epitopes. Importantly, LDH release assays demonstrated that anti-pE120R antibodies triggered NK cell-mediated ADCC. Notably, ASFV replication in HEK293T-pE120R cells was not promoted. Conclusions: In summary, pE120R was associated with antibody production in a cytotoxicity assay. The ability of this antigen to induce protective immunity, if any, requires further evaluation in vivo. Full article

Background/Objectives: Canine visceral leishmaniasis (CVL) is one of the main neglected protozoan diseases in the world. Dogs play a fundamental role in the maintenance of Leishmania infantum in the Americas, and we have already encountered resistance problems with drugs currently used in these animals. Methods: In view of this, two new immunotherapeutic protocols were tested in 48 dogs, using L. amazonensis antigens plus saponin (LaSap) and only L. amazonensis antigens (La) as a control group. Dogs naturally infected with L. infantum were divided into four groups, according to clinical staging. A total of 24 dogs (stages 1 and 2) received a four-dose protocol, and another 24 dogs (stages 3 to 5) received six doses. All animals received a booster dose every three months until they were one year old. Results: Our results showed that dogs in the early stages of the disease respond better and are able to remain stable for longer, maintaining baseline laboratory biomarkers, in addition to having a lower parasite load. Conclusions: On the other hand, dogs in more advanced stages have a poor response, with stage 3 being a key point in clinical progression or regression. Full article

Background: Hematopoietic cell transplantation (HCT) and chimeric antigen receptor T-cell (CAR-T) therapy have markedly improved survival in pediatric patients with hematological malignancies. However, these treatments cause profound immunosuppression, leading to significant susceptibility to vaccine-preventable diseases (VPDs), including invasive pneumococcal disease and measles. Timely and tailored immunization strategies are crucial to mitigate infectious risks in this vulnerable population. Methods: We conducted a narrative review of the English-language literature from 2000 to 2024, including clinical guidelines, surveys, and original studies, to evaluate immune reconstitution and vaccination practices in pediatric patients undergoing HCT and CAR-T therapy. Literature searches in PubMed, Scopus, and Web of Science used disease-specific, therapy-specific, and pathogen-specific terms. Data synthesis focused on vaccine schedules, immune recovery markers, and adherence challenges. Results: Profound immune deficits post-HCT and CAR-T therapy compromise both innate and adaptive immunity, often necessitating revaccination. Key factors influencing vaccine responses include time since therapy, graft source, immunosuppressive treatments, and chronic graft-versus-host disease. Although inactivated vaccines are generally safe from three to six months post-HCT, live vaccines remain contraindicated until documented immune recovery. CAR-T therapy introduces unique challenges due to prolonged B-cell aplasia and hypogammaglobulinemia, leading to delayed or reduced vaccine responses. Despite established guidelines, real-world adherence to vaccination schedules remains suboptimal, driven by institutional, logistic, and patient-related barriers. Conclusions: Effective vaccination strategies are essential for reducing infectious morbidity in pediatric HCT and CAR-T recipients. Personalized vaccine schedules, immune monitoring, and multidisciplinary coordination are critical to bridging gaps between guidelines and practice, ultimately improving long-term outcomes for immunocompromised children. Full article

Elite athletes are at an increased risk of infections due to behavioral and social factors and frequent travel. Furthermore, heavy physical exercise may induce immunosuppression. Most infections in athletes are acute respiratory illnesses (ARIs) with various viral etiologies. Although athletes, as young, healthy adults, are not at risk for severe infections, a prolonged ARI may ruin a training season or a significant competition or may spread within a sports team. Many common infections are vaccine-preventable. This Opinion advocates for more active vaccination among athletes, although some of the vaccines are not officially recommended for young adults. New respiratory syncytial virus (RSV) protein vaccines are effective and well-tolerated. Yearly influenza and COVID-19 vaccinations are strongly recommended. Conjugated polyvalent pneumococcal vaccines are recommended because they may also induce protection against respiratory viral infections. Pertussis and measles outbreaks are occurring globally. The history of measles vaccination should be reviewed, and consideration should be given to a pertussis booster vaccination (Tdap). A recombinant vaccine can effectively prevent herpes zoster. The vaccination of elite athletes is a cost-effective and powerful tool, but it is currently underused. The sports medicine community can address vaccine hesitancy among athletes by listening to their concerns and giving accurate information. Full article

The 2022 global mpox outbreak, caused by clade IIb of the monkeypox virus (MPXV), prompted emergency use authorisation of the Modified Vaccinia Ankara–Bavarian Nordic (MVA-BN) vaccine, previously approved for smallpox prevention. Understanding immune responses to the MVA-BN vaccine is critical to inform both current and future mpox vaccine policy, particularly amid reports of breakthrough infections in vaccinated persons, uncertainty about the durability of vaccine-induced protection, and the emergence of further outbreaks of mpox from different viral clades, including the clade I-driven public health emergency of international concern. MVA-BN elicits binding and neutralising antibody, memory B cells, and T cell responses. Immune responses vary by host factors, prior orthopoxvirus exposure, and dosing regimens. While seroconversion is generally robust, circulating antibody titres often wane rapidly, particularly in vaccinia-naïve and/or immunocompromised individuals, including people with HIV. Vaccine-induced neutralising antibody responses to MPXV are frequently lower than to vaccinia virus, and their role in protection remains ill-defined. In contrast, T cell responses appear more sustained and may support long-term immunity in the absence of persistent antibody titres. This narrative review synthesises current evidence on the immunogenicity and durability of MVA-BN vaccination, highlights challenges in assay interpretation, and outlines key research priorities, including the need to explore correlates of protection, booster strategies, and next-generation vaccine design. Full article