Nota técnica N. 13/2024 - SES/GVEDT: aumento de casos de coqueluche / Technical note N. 13/2024 - SES/GVEDT: increase in pertussis cases

Nota técnica com o objetivo de alertar os gestores e profissionais de saúde quanto ao aumento de casos confirmados por coqueluche em 17 países em 2024, bem como em alguns estados brasileiros, conforme Nota técnica nº 70/2024 - DPNI/SVSA/MS e também reforçar para a necessidade de alcançar as coberturas vacinais conforme preconizado pelo Ministério da Saúde, além de adoção de medidas para fortalecimento da vigilância epidemiológica e laboratorial do agravo diante da suspeita clínica, diagnóstico e tratamento oportuno da doença a fim de evitar a morbimortalidade pela doença no Estado de Goiás

Technical note with the aim of alerting managers and health professionals regarding the increase in confirmed cases of pertussis in 17 countries in 2024, as well as in some Brazilian states, according to Technical Note nº 70/2024 - DPNI/SVSA/MS and also to reinforce to the need to achieve vaccination coverage as recommended by the Ministry of Health, in addition to adopting measures to strengthen epidemiological and laboratory surveillance of the disease in the face of clinical suspicion, diagnosis and timely treatment of the disease in order to avoid morbidity and mortality due to the disease in the State from Goiás

BPP0974 is a Bordetella parapertussis adhesin expressed in the avirulent phase, implicated in biofilm formation and intracellular survival.

B. parapertussis is a bacterium that causes whooping cough, a severe respiratory infection disease, that has shown an increased incidence in the population. Upon transmission through aerosol droplets, the initial steps of host colonization critically depend on the bacterial adhesins. We here described BPP0974, a B. parapertussis protein that exhibits the typical domain architecture of the large repetitive RTX adhesin family. BPP0974 was found to be retained in the bacterial membrane and secreted into the culture medium. This protein was found overexpressed in the avirulent phase of B. parapertussis, the phenotype proposed for initial host colonization. Interestingly, BPP0974 was found relevant for the biofilm formation as well as involved in the bacterial attachment to and survival within the respiratory epithelial cells. Taken together, our results suggest a role for BPP0974 in the early host colonization and pathogenesis of B. parapertussis.

Bordetella pertussis targets the basolateral membrane of polarized respiratory epithelial cells, gets internalized, and survives in intracellular locations.

The airway epithelial barrier is a continuous highly organized cell layer that separates the exterior from the underlying mucosal tissue, preventing pathogen invasion. Several respiratory pathogens have evolved mechanisms to compromise this barrier, invade and even reside alive within the epithelium. Bordetella pertussis is a persistent pathogen that infects the human airway epithelium, causing whooping cough. Previous studies have shown that B. pertussis survives inside phagocytic and nonphagocytic cells, suggesting that there might be an intracellular stage involved in the bacterial infectious process and/or in the pathogen persistence inside the host. In this study we found evidence that B. pertussis is able to survive inside respiratory epithelial cells. According to our results, this pathogen preferentially attaches near or on top of the tight junctions in polarized human bronchial epithelial cells and disrupts these structures in an adenylate cyclase-dependent manner, exposing their basolateral membrane. We further found that the bacterial internalization is significantly higher in cells exposing this membrane compared with cells only exposing the apical membrane. Once internalized, B. pertussis mainly remains in nondegradative phagosomes with access to nutrients. Taken together, these results point at the respiratory epithelial cells as a potential niche of persistence.

Effect of immunization registry-based provider reminder to initiate HPV vaccination at age 9, Washington state.

Human papillomavirus (HPV) vaccination rates are lower than Tetanus-diphtheria-pertussis (Tdap) and Meningococcal conjugate (MenACWY) rates, although the Advisory Committee on Immunization Practices recommends all three vaccines be given routinely at age 11-12. Evidence is mounting that children who initiate HPV vaccination starting at age 9 are more likely to complete the series on time. Washington state implemented a provider reminder through its immunization information system (WAIIS) in January 2023 to increase HPV vaccine initiation at 9-years-old by updating the forecasted recommended age for HPV from age 11 to 9. The effectiveness of provider reminders when implemented via an immunization information system (IIS) is poorly understood. We evaluated the impact of this forecast update using a seasonally adjusted interrupted time series regression of weekly HPV initiations at 9-years-old before and after implementation. We also examined time series trends of vaccine administration between 2018 and 2023 for HPV initiation at age 9, as well as Tdap, MenACWY and HPV initiation at age 11. The WAIIS forecast update doubled the weekly rate of HPV initiation among 9-year-olds in Washington state, although the weekly count of initiation at 9 remains far lower than initiations at 11. Jurisdictions wanting to increase HPV vaccine initiation at earlier ages should consider updating their forecast algorithm and investing in complementary evidence-based strategies such as provider and parent education, and clinic-based quality improvement efforts. The reach of IIS forecaster updates may be enhanced by working with administrators of electronic medical record systems to ensure parity of provider prompts with IIS.

Evaluation of Detection and Efficacy of Decontamination of Respiratory Pathogens Including SARS-CoV-2 on Basic Military Trainee Gas Masks.

INTRODUCTION: Basic military trainee (BMT) gas mask training poses a potential mechanism of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) transmission. After training, gas masks are decontaminated. Insufficient decontamination can lead to viral transmission in the next training class. To our knowledge, the decontamination process has not been validated for efficacy in removing respiratory pathogens such as SARS-CoV-2. MATERIALS AND METHODS: Inactivated strains of SARS-CoV-2, influenza A and B, and Bordetella pertussis were separately inoculated onto gas masks in the emitter area (n = 5). Pathogen detection in swabs collected from gas masks was performed by real-time polymerase chain reaction (RT-PCR) using the BioFire® RP2.1 panel and Biomeme Franklin system. For decontamination efficacy experiments, pathogens were inoculated onto gas masks, and contaminated areas were swabbed before and after decontamination, with detection using both PCR platforms. Lastly, 65 gas masks were swabbed after gas mask training, and again after the trainees and guardians decontaminated the masks, to identify the presence of any respiratory pathogen exhaled onto the gas masks. RESULTS: All four pathogens were detected by both PCR platforms. The BioFire® FilmArray® was more sensitive than the Biomeme platform. Decontamination resulted in undetectable levels of all three viruses. B. pertussis was detected on one mask after decontamination. Experiments with live B. pertussis validated that decontamination eliminated all viable bacteria from gas masks. For BMT sampling, all masks were negative for SARS-CoV-2. One mask tested positive for coronavirus 229E. Once decontaminated, all masks tested negative. CONCLUSIONS: BMT gas masks can be monitored for the presence of respiratory pathogens using RT-PCR. The decontamination process removed all viable respiratory pathogens tested from the gas masks. This study demonstrates that RT-PCR can be used to conduct pathogen surveillance on BMT gas masks after training and that the current decontamination process is effective to eliminate respiratory viruses including SARS-CoV-2.

Adenylate cyclase toxin of Bordetella parapertussis disrupts the epithelial barrier granting the bacterial access to the intracellular space of epithelial cells.

B. parapertussis is one of the etiological agents of whooping cough. Once inhaled, the bacteria bind to the respiratory epithelium and start the infection. Little is known about this first step of host colonization and the role of the human airway epithelial barrier on B. parapertussis infection. We here investigated the outcome of the interaction of B. parapertussis with a polarized monolayer of respiratory epithelial cells. Our results show that B. parapertussis preferentially attaches to the intercellular boundaries, and causes the disruption of the tight junction integrity through the action of adenylate cyclase toxin (CyaA). We further found evidence indicating that this disruption enables the bacterial access to components of the basolateral membrane of epithelial cells to which B. parapertussis efficiently attaches and gains access to the intracellular location, where it can survive and eventually spread back into the extracellular environment. Altogether, these results suggest that the adenylate cyclase toxin enables B. parapertussis to overcome the epithelial barrier and eventually establish a niche of persistence within the respiratory epithelial cells.

Immunogenicity of tetanus, diphtheria and acellular pertussis vaccination among pregnant women living with and without HIV.

OBJECTIVE: Vaccination during pregnancy with tetanus-diphtheria-acellular pertussis (Tdap) vaccine is recommended to protect the young infants against pertussis. There is a paucity of data on immune responses to Tdap in pregnant women with HIV (PWWH), and its impact on the protection of their infants has not been described. METHODS: In an open label phase IV clinical trial in South Africa, we evaluated the immunogenicity and safety of Tdap in PWWH compared with HIV-uninfected women. Antigen-specific immunoglobulin G (IgG) to pertussis toxoid, filamentous haemagglutinin, pertactin, fimbriae, diphtheria and tetanus were measured by electrochemiluminescence-based multiplex assay. RESULTS: Overall, 91 PWWH and 136 HIV-uninfected pregnant women were enrolled. All PWWH were on antiretroviral treatment and 94.5% had HIV viral loads <40 copies per millilitre. Antibody levels prevaccination were lower among PWWH compared with HIV-uninfected women for all antigens. At 1 month postvaccination PWWH compared with HIV-uninfected women had lower fold-increase and antibody concentrations for all epitopes. Also, a lower proportion of PWWH achieved ≥4-fold increase from pre to postvaccination for pertussis toxoid and pertactin, or diphtheria IgG levels ≥0.1 IU/ml and ≥1 IU/ml postvaccination. Adverse events postvaccination were similar in PWWH and HIV-uninfected. CONCLUSION: Tdap vaccination was safe and immunogenic. PWHW had, however, attenuated humoral immune responses, which could affect the effectiveness of protecting their infants against pertussis compared with those born to women without HIV.ClinicalTrials.gov identifier: NCT05264662.

Childhood vaccination uptake among children born in Aotearoa New Zealand based on parental nationality.

Migrants and refugees generally experience immunization inequities compared to their host populations. Childhood vaccination coverage rates are influenced by a complex set of interrelated factors, including child and parental nativity. Coverage rates for MMR, pertussis, and HPV vaccines were compared among children born in Aotearoa New Zealand (NZ) of overseas-born parents or NZ-born parents. A nationwide retrospective cohort study was conducted using linked, de-identified data. Logistic regression models examined the most influential factors contributing to differences in timely vaccine uptake. Of the total study population who had received all scheduled vaccines (N = 760,269), 32.9% were children of migrant parents. Children of migrant parents had higher rates of complete and timely uptake for MMR, pertussis, and HPV vaccinations compared to non-migrant children. NZ-born children of migrant parents were significantly more likely to receive MMR and pertussis-containing vaccines on-time compared to those of non-migrants. All included factors, except for the child's gender and parents' English ability, significantly influenced vaccine uptake. Among NZ-born children of migrant parents, additional logistic modeling found significant differences based on parental duration of residence, visa group, and region of nationality. Findings point to the importance of differentiating between parent versus child nativity when examining immunization coverage. While vaccination rates were higher for NZ-born children of migrant parents, compared to non-migrant parents, timely coverage rates across both groups were below national targets. Continued efforts are needed to improve timely immunization service delivery to address suboptimal and inequitable coverage.

Immediate and long-term changes in infectious diseases in China at the "First-level-response", "Normalized-control" and "Dynamic-COVID-zero" stages from 2020 to 2022: a multistage interrupted-time-series-analysis.

BACKGROUND: From January 2020 to December 2022, China implemented "First-level-response", "Normalized-control" and "Dynamic-COVID-zero" to block the COVID-19 epidemic; however, the immediate and long-term impact of three strategies on other infectious diseases and the difference in their impact is currently unknown. We aim to provide a more comprehensive understanding of the impact of non-pharmacological interventions (NPIs) on infectious diseases in China. METHODS: We collected data on the monthly case count of infectious diseases in China from January 2015 to July 2022. After considering long-term trends using the Cox-Stuart test, we performed the two ratio Z tests to preliminary analyze the impact of three strategies on infectious diseases. Next, we used a multistage interrupted-time-series analysis fitted by the Poisson regression to evaluate and compare the immediate and long-term impact of three strategies on infectious diseases in China. RESULTS: Compared to before COVID-19, the incidence of almost all infectious diseases decreased immediately at stages 1, 2, and 3; meanwhile, the slope in the incidence of many infectious diseases also decreased at the three stages. However, the slope in the incidence of all sexually transmitted diseases increased at stage 1, the slope in the incidence of all gastrointestinal infectious diseases increased at stage 2, and the slope in the incidence of some diseases such as pertussis, influenza, and brucellosis increased at stage 3. The immediate and long-term limiting effects of "Normalized-control" on respiratory-transmitted diseases were weaker than "First-level-response" and the long-term limiting effects of "Dynamic-COVID-zero" on pertussis, influenza, and hydatid disease were weaker than "Normalized-control". CONCLUSIONS: Three COVID-19 control strategies in China have immediate and long-term limiting effects on many infectious diseases, but there are differences in their limiting effects. Evidence from this study shows that pertussis, influenza, brucellosis, and hydatid disease began to recover at stage 3, and relaxation of NPIs may lead to the resurgence of respiratory-transmitted diseases and vector-borne diseases.

Vaccination schedule for adolescents. Consensus of the AEV, CAV-AEP and SEMA.

We present the consensus document on the immunization schedule for adolescents developed by 3 scientific societies: the Spanish Association of Pediatrics (AEP), through its Advisory Committee on Vaccines (CAV-AEP), the Spanish Society of Adolescent Medicine (SEMA) and the Spanish Association of Vaccinology (AEV). There are particularities in infectious disease during adolescence, such as an increased susceptibility to pertussis, poorer outcomes of chickenpox, mumps and hepatitis A, a high incidence of sexually transmitted infections or increased prevalence of meningococcal carriage. The document analyses the schedule for adolescents in the context of vaccination policy overall. It contemplates the vaccines to be included in the immunization schedule for healthy adolescents: against invasive meningococcal disease (tetravalent ACWY and B), against human papillomavirus (which should be gender-neutral), against pertussis, against influenza and against SARS-CoV-2 (in unvaccinated individuals and at-risk groups). It is worth noting that the 4CMenB vaccine appears to confer some protection against gonococcal infection, which would be a considerable added value for adolescents. The vaccination of adolescents belonging to risk groups or travelling abroad also needs to be contemplated, as is the case in any other age group. Vaccination against hepatitis A, which is included in the routine immunization schedule of Catalonia, Ceuta and Melilla from the second year of life, should also be considered a priority in adolescents traveling to endemic areas.

Improved serologic responses to DTaP over Tdap vaccination in adult hematopoietic cell transplant recipients.

BACKGROUND: Hematopoietic cell transplantation (HCT) recipients have reduced antibody titers to tetanus, diphtheria, and pertussis. Tdap is approved for revaccinating adult HCT recipients in the United States, whereas DTaP is not approved in this population. To our knowledge, no studies to date have compared responses to DTaP versus Tdap in adult HCT patients. We conducted a retrospective study comparing responses to DTaP versus Tdap vaccines in otherwise similar adult HCT patients in order to determine if one of these vaccines elicits superior antibody responses. METHODS: We evaluated 43 allogeneic and autologous transplant recipients as a combined cohort and as separate subsets for vaccine specific antibody titers and proportion of strong vaccine responders. Subset analysis focused on the autologous transplant recipients. RESULTS: Higher median antibody titers were found to all vaccine components among DTaP recipients (diphtheria p = .021, pertussis p = .020, tetanus p = .007). DTaP recipients also had more strong responders to diphtheria and pertussis (diphtheria p = .002, pertussis p = .006). Among the autologous HCT recipient subset, there were more strong responders to diphtheria (p = .036). CONCLUSIONS: Our data shows that post-HCT vaccination with DTaP leads to higher antibody titers and more strong responders, which suggests that DTaP is more effective than Tdap in HCT recipients.

Missed Opportunities for Adolescent Immunizations at Well-Care Visits During the COVID-19 Pandemic.

PURPOSE: The Coronavirus Disease 2019 pandemic disrupted healthcare, but the impact on vaccination missed opportunities (MOs, vaccine-eligible visits without vaccination) is unknown. We evaluated pandemic-related trends in MOs at adolescent well-care visits for three vaccines: human papillomavirus; quadrivalent meningococcal conjugate; and tetanus, diphtheria, and acellular pertussis (Tdap). METHODS: We analyzed electronic health record data from 24 pediatric primary care practices in 13 states from 1/1/2018 to 12/31/2021. Segmented logistic regression estimated risk differences for MOs during the pandemic relative to prepandemic trends. RESULTS: Among 106,605 well-care visits, we observed decreases in MOs prepandemic followed by an increase in MOs during the pandemic for all three vaccines. Relative to prepandemic, MOs increased for human papillomavirus (+15.9%, 95% confidence interval [CI]: 11.7%, 20.1%), meningococcal conjugate (+9.4%, 95% CI: 5.2%, 13.7%), and tetanus, diphtheria, and acellular pertussis (Tdap) (+ 8.2%, 95% CI: 4.3%, 12.1%). DISCUSSION: Increases in vaccine MOs during the pandemic equaled or exceeded pre-pandemic decreases. Reducing MOs in adolescent well-care could raise vaccine coverage.

Abordaje integral de infecciones respiratorias agudas virales y coqueluche / Comprehensive approach to acute viral respiratory infections and whooping cough

Informe sobre el objetivo del abordaje de estas patologías, desde el Ministerio de Salud de la Ciudad de Buenos Aires: Medidas de prevención; Priorización de diagnóstico; Estrategia integrada de vigilancia de la Infecciones Respiratorias Agudas de posible origen viral; Vigilancia Universal; Vigilancia epidemiológica de coqueluche (tos convulsa); y Recomendaciones sobre el uso de antivirales para influenza; (AU)

Estimating the pertussis burden in adolescents and adults in the United States between 2007 and 2019.

We developed a machine learning algorithm to identify undiagnosed pertussis episodes in adolescent and adult patients with reported acute respiratory disease (ARD) using clinician notes in an electronic healthcare record (EHR) database. Here, we utilized the algorithm to better estimate the overall pertussis incidence within the Optum Humedica clinical repository from 1 January 2007 through 31 December 2019. The incidence of diagnosed pertussis episodes was 1-5 per 100,000 annually, consistent with data registered by the US Centers for Disease Control and Prevention (CDC) over the same time period. Among 18,573,496 ARD episodes assessed, 1,053,946 were identified (i.e. algorithm-identified) as likely undiagnosed pertussis episodes. Accounting for these undiagnosed pertussis episodes increased the estimated pertussis incidence by 110-fold on average (34-474 per 100,000 annually). Risk factors for pertussis episodes (diagnosed and algorithm-identified) included asthma (Odds ratio [OR] 2.14; 2.12-2.16), immunodeficiency (OR 1.85; 1.78-1.91), chronic obstructive pulmonary disease (OR 1.63; 1.61-1.65), obesity (OR 1.44; 1.43-1.45), Crohn's disease (OR 1.39; 1.33-1.45), diabetes type 1 (OR 1.21; 1.17-1.24) and type 2 (OR 1.12; 1.1-1.13). Of note, all these risk factors, except Crohn's disease, increased the likelihood of severe pertussis. In conclusion, the incidence of pertussis in the adolescent and adult population in the USA is likely substantial, but considerably under-recognized, highlighting the need for improved clinical awareness of the disease and for improved control strategies in this population. These results will help better inform public health vaccination and booster programs, particularly in those with underlying comorbidities.

Revaccination of children with acute lymphoblastic leukemia following completion of chemotherapy.

BACKGROUND: Intensive chemotherapy for acute lymphoblastic leukemia (ALL) may affect the immune system and potentially the immune memory causing antibodies provided by vaccination to disappear. There are disagreements regarding the guidelines for posttreatment immunization strategy. METHODS: Ninety-six children (aged 1-18 years at diagnosis) who completed chemotherapy for ALL were recruited. Antibody levels in the patient's serum against measles, varicella, polio, pertussis, hepatitis A, and hepatitis B were tested after completion of chemotherapy in patients who were fully vaccinated against these agents. Children who did not have positive serology to specific agents were revaccinated with a single dose accordingly. Antibody concentrations were measured again at least 4 weeks after revaccination. RESULTS: Positive antibody levels varied between the different agents. The highest percentage of positive serology was against polio (87%) and the lowest against pertussis (4%) (p < .001). There were significant differences between patients with high risk (HR) and non-HR ALL regarding serology status for some vaccines. After revaccination, the levels of response to each booster dose were significantly different: 100% after booster dose for varicella and polio, and only 34% after pertussis booster. CONCLUSIONS: Loss of humoral protection for vaccine preventable diseases is a common finding among patients with ALL. Revaccination with one dose of vaccine after completion of chemotherapy achieved seroconversion in 34-100% of the patients depending on the type of vaccine. We recommend this revaccination schedule to all children who completed ALL therapy and were previously fully vaccinated.

Multiple rib and vertebral fractures associated with Bordetella pertussis infection: a case report.

BACKGROUND: Pertussis is a highly contagious respiratory disease caused by the bacterium Bordetella pertussis, characterized by paroxysms of severe coughing, and predominantly affects children. We report the first case of multiple fractures in the ribs, lumbar spine, and sacrum associated with severe coughing caused by Bordetella pertussis infection in an adult. CASE PRESENTATION: A 49-year-old female presented with acute-onset chest wall pain for 3 weeks. Imaging results revealed multiple fractures in the ribs and vertebrae, as well as bilateral pleural effusion, pericardial effusion, right pneumothorax, and enlargement of the left parapharyngeal and subclavian lymph nodes. The patient's bone density scan, autoimmune antibodies, bone marrow biopsy, and sacral bone biopsy all came back normal. Imaging test results found no evidence of solid tumors or active TB infection. The patient later recalled having violent coughing prior to the onset of chest pain and several family members having similar symptoms. Her blood sample was sent to the CDC, revealing Bordetella pertussis toxin (PT) IgG titer of 110.68 IU/mL. The patient was diagnosed with pertussis and multiple stress fractures from violent coughing. Symptomatic treatments were administered, and the patient's symptoms improved. The patient was followed up 8 weeks later, she reported no more coughing or chest pain. CONCLUSIONS: Pertussis is not just a pediatric disease, but diagnosis in adults is challenging as patients may present with a myriad of confusing symptoms, such as multiple stress fractures due to violent coughing. Medical and epidemiological histories are key to reaching the correct diagnosis, which is essential for appropriate treatments to avoid further complications. Adult immunization should be suggested both for the protection of the adult population and to prevent transmission to children.

Pasteurian Contributions to the Study of Bordetella pertussis Toxins.

As a tribute to Louis Pasteur on the occasion of the 200th anniversary of his birth, this article summarizes the main contributions of scientists from Pasteur Institutes to the current knowledge of toxins produced by Bordetella pertussis. The article therefore focuses on publications authored by researchers from Pasteur Institutes and is not intended as a systematic review of B. pertussis toxins. Besides identifying B. pertussis as the causative agent of whooping cough, Pasteurians have made several major contributions with respect to the structure-function relationship of the Bordetella lipo-oligosaccharide, adenylyl cyclase toxin and pertussis toxin. In addition to contributing to the understanding of these toxins' mechanisms at the molecular and cellular levels and their role in pathogenesis, scientists at Pasteur Institutes have also exploited potential applications of the gathered knowledge of these toxins. These applications range from the development of novel tools to study protein-protein interactions over the design of novel antigen delivery tools, such as prophylactic or therapeutic vaccine candidates against cancer and viral infection, to the development of a live attenuated nasal pertussis vaccine. This scientific journey from basic science to applications in the field of human health matches perfectly with the overall scientific objectives outlined by Louis Pasteur himself.

Bordetella parapertussis adenylate cyclase toxin promotes the bacterial survival to the encounter with macrophages.

B. parapertussis is a whooping cough etiological agent, whose incidence in the population has increased remarkably. Virulence factors involved in the bacterial infection, however, remain poorly investigated. We here studied the role of adenylate cyclase (CyaA), the main toxin of B. parapertussis, in the outcome of the bacterial interaction with macrophages. Our results showed that B. parapertussis CyaA intoxicates human macrophages, prevents bacterial phagocytosis and precludes phago-lysosomal fusion eventually promoting the bacterial survival to the encounter with these immune cells. Accordingly, we found that B. parapertussis CyaA induces the transcriptional downregulation of host genes encoding for antimicrobial peptides, proteins involved in bacterial intracellular killing, and the pro-inflammatory cytokine TNF-α, while induces the upregulation of the anti-inflammatory cytokine IL-10. Together with previous reports suggesting a protective role of B. parapertussis CyaA against neutrophils bactericidal activity, the results of this study suggest a central role of CyaA in B. parapertussis immune evasion and persistence.

Vaccine Adherence and Postvaccination Serological Status of Pediatric Allogeneic Hematopoietic Stem Cell Transplant Recipients: A Single-center Experience.

Despite developing consensus guidelines addressing immunization after hematopoietic stem cell transplantation (HSCT), studies showed deviations from recommended immunization practices commonly occur. Difference between the ideal scenario presented in guidelines and real-life scenarios is one of the most recognized barriers to implementing recommended practices. Therefore, this study aimed to evaluate pediatric allogeneic HSCT recipients' adherence to revaccination schedule and evaluate the serological status after immunization. Transplant and vaccination records of children who were followed up at least 2 years after HSCT, postvaccination antibody results of vaccine-preventable diseases were evaluated retrospectively. Total of 173 patients have enrolled in this study. Median revaccination onset time was post-transplant 15 months. Adherence to revaccination program was 30% for inactive and 11.4% for live vaccines. Oral polio vaccine was given to 22 patients, and Bacille-Calmette-Guerin vaccine was applied to 3. Seropositivity after revaccination was >90% for Hepatitis B, Hepatitis A, pertussis, and measles, and it was 88.5% for rubella, 80% for mumps and varicella. Measles seropositivity was low in children with hemoglobinopathy. In subgroup assessments of pertussis, patients vaccinated with low antigen-containing pertussis vaccine (Tdap) had higher seropositivity of adenylate cyclase toxin. Our findings revealed the importance of careful monitoring of current practices in pediatric HSCT recipients.