Transition practice for primary immunodeficiency diseases in Southeast Asia: a regional survey.

Introduction: With increased diagnostic capabilities and treatment modalities in the field of primary immunodeficiencies (PID), many pediatric patients survive beyond childhood and experience a change of care to the adult-oriented healthcare system. Unfortunately, the transition pathways for PID are less clearly defined, resulting in deterioration of quality of care in adulthood. Hence, this is the first regional study to address PID clinicians' opinions on practices and challenges of transition care in 7 Southeast Asia (SEA) countries. Methods: We adopted a cross-sectional study design through an online survey platform to enquire opinions of transition practices from expert representatives in 7 SEA countries. Results: Regionally, 3 out 7 countries reported having no practice of transition care. Among cited challenges were reluctant adaptation by patients and caregivers to unfamiliarized adult healthcare systems, inadequate ratio of adult immunologists to patients and lack of facilities for transfer. Discussion and conclusion: Our study provides evidence to advocate policy makers on the importance of standardized integration of transition practice towards betterment of transiting PID patients into adulthood.

Targeted Gene Sanger Sequencing Should Remain the First-Tier Genetic Test for Children Suspected to Have the Five Common X-Linked Inborn Errors of Immunity.

To address inborn errors of immunity (IEI) which were underdiagnosed in resource-limited regions, our centre developed and offered free genetic testing for the most common IEI by Sanger sequencing (SS) since 2001. With the establishment of The Asian Primary Immunodeficiency (APID) Network in 2009, the awareness and definitive diagnosis of IEI were further improved with collaboration among centres caring for IEI patients from East and Southeast Asia. We also started to use whole exome sequencing (WES) for undiagnosed cases and further extended our collaboration with centres from South Asia and Africa. With the increased use of Next Generation Sequencing (NGS), we have shifted our diagnostic practice from SS to WES. However, SS was still one of the key diagnostic tools for IEI for the past two decades. Our centre has performed 2,024 IEI SS genetic tests, with in-house protocol designed specifically for 84 genes, in 1,376 patients with 744 identified to have disease-causing mutations (54.1%). The high diagnostic rate after just one round of targeted gene SS for each of the 5 common IEI (X-linked agammaglobulinemia (XLA) 77.4%, Wiskott-Aldrich syndrome (WAS) 69.2%, X-linked chronic granulomatous disease (XCGD) 59.5%, X-linked severe combined immunodeficiency (XSCID) 51.1%, and X-linked hyper-IgM syndrome (HIGM1) 58.1%) demonstrated targeted gene SS should remain the first-tier genetic test for the 5 common X-linked IEI.

Differences between peptide profiles of extensive hydrolysates and their influence on functionality for the management of cow's milk allergy: A short review.

Extensively hydrolyzed formulas (eHFs) are recommended for the dietary management of cow's milk protein allergy (CMPA) in non-exclusively breastfed infants. Studies show that peptide profiles differ between eHFs. This short review aims to highlight the variability in peptides and their ability to influence allergenicity and possibly the induction of tolerance by different eHFs. The differences between eHFs are determined by the source of the protein fraction (casein or whey), peptide size-distribution profile and residual ß-lactoglobulin which is the most immunogenic and allergenic protein in bovine milk for human infants as it is not present in human breastmilk. These differences occur from the hydrolyzation process which result in variable IgE reactivity against cow's milk allergen epitopes by subjects with CMPA and differences in the Th1, Th2 and pro-inflammatory cytokine responses elicited. They also have different effects on gut barrier integrity. Results suggest that one particular eHF-casein had the least allergenic potential due to its low residual allergenic epitope content and demonstrated the greatest effect on restoring gut barrier integrity by its effects on mucin 5AC, occludin and Zona Occludens-1 in human enterocytes. It also increased the production of the tolerogenic cytokines Il-10 and IFN-γ. In addition, recent studies documented promising effects of optional functional ingredients such as pre-, pro- and synbiotics on the management of cow's milk allergy and induction of tolerance, in part via the induction of the production of short chain fatty acids. This review highlights differences in the residual allergenicity, peptide size distribution, presence of optional functional ingredients and overall functionality of several well-characterized eHFs which can impact the management of CMPA and the ability to induce immune tolerance to cow's milk protein.

Implementation of Universal Newborn Screening for Severe Combined Immunodeficiency in Singapore While Continuing Routine Bacille-Calmette-Guerin Vaccination Given at Birth.

Introduction: Severe Combined Immunodeficiency (SCID) is generally fatal if untreated; it predisposes to severe infections, including disseminated Bacille-Calmette-Guerin (BCG) disease from BCG vaccination at birth. However, delaying BCG vaccination can be detrimental to the population in tuberculosis-endemic regions. Early diagnosis of SCID through newborn screening followed by pre-emptive treatment with anti-mycobacterial therapy may be an alternative strategy to delaying routine BCG vaccination. We report the results of the first year of newborn SCID screening in Singapore while continuing routine BCG vaccination at birth. Method: Newborn screening using a T-cell receptor excision circle (TREC) assay was performed in dried blood spots received between 10 October 2019 to 9 October 2020 using the Enlite Neonatal TREC kit. Patients with low TREC had lymphocyte subset analysis and full blood count performed to determine the severity of lymphopenia and likelihood of SCID to guide further management. Results: Of the 35888 newborns screened in 1 year, no SCID cases were detected, while 13 cases of non-SCID T-cell lymphopenia (TCL) were picked up. Using a threshold for normal TREC to be >18 copies/µL, the retest rate was 0.1% and referral rate to immunologist was 0.04%. Initial low TREC correlated with low absolute lymphocyte counts (ALC), and subsequent normal ALC corresponded with increases in TREC, thus patients with normal first CD3+ T cell counts were considered to have transient idiopathic TCL instead of false positive results. 7/13 (54%) had secondary TCL (from sepsis, Trisomy 21 with hydrops and stoma losses or chylothorax, extreme prematurity, or partial DiGeorge Syndrome) and 6/13 (46%) had idiopathic TCL. No cases of SCID were diagnosed clinically in Singapore during this period and for 10 months after, indicating that no cases were missed by the screening program. 8/9 (89%) of term infants with abnormal TREC results received BCG vaccination within the first 6 days of life when TREC and ALC were low. No patients developed BCG complications after a median follow-up of 17 months. Conclusion: Newborn screening for SCID can be implemented while continuing routine BCG vaccination at birth. Patients with transient TCL and no underlying primary immunodeficiency are able to tolerate BCG vaccination.

Phenomic Analysis of Chronic Granulomatous Disease Reveals More Severe Integumentary Infections in X-Linked Compared With Autosomal Recessive Chronic Granulomatous Disease.

Background: Chronic granulomatous disease (CGD) is an inborn error of immunity (IEI), characterised by recurrent bacterial and fungal infections. It is inherited either in an X-linked (XL) or autosomal recessive (AR) mode. Phenome refers to the entire set of phenotypes expressed, and its study allows us to generate new knowledge of the disease. The objective of the study is to reveal the phenomic differences between XL and AR-CGD by using Human Phenotype Ontology (HPO) terms. Methods: We collected data on 117 patients with genetically diagnosed CGD from Asia and Africa referred to the Asian Primary Immunodeficiency Network (APID network). Only 90 patients with sufficient clinical information were included for phenomic analysis. We used HPO terms to describe all phenotypes manifested in the patients. Results: XL-CGD patients had a lower age of onset, referral, clinical diagnosis, and genetic diagnosis compared with AR-CGD patients. The integument and central nervous system were more frequently affected in XL-CGD patients. Regarding HPO terms, perianal abscess, cutaneous abscess, and elevated hepatic transaminase were correlated with XL-CGD. A higher percentage of XL-CGD patients presented with BCGitis/BCGosis as their first manifestation. Among our CGD patients, lung was the most frequently infected organ, with gastrointestinal system and skin ranking second and third, respectively. Aspergillus species, Mycobacterium bovis, and Mycobacteirum tuberculosis were the most frequent pathogens to be found. Conclusion: Phenomic analysis confirmed that XL-CGD patients have more recurrent and aggressive infections compared with AR-CGD patients. Various phenotypic differences listed out can be used as clinical handles to distinguish XL or AR-CGD based on clinical features.

Singapore Undiagnosed Disease Program: Genomic Analysis aids Diagnosis and Clinical Management.

OBJECTIVE: Use next-generation sequencing (NGS) technology to improve our diagnostic yield in patients with suspected genetic disorders in the Asian setting. DESIGN: A diagnostic study conducted between 2014 and 2019 (and ongoing) under the Singapore Undiagnosed Disease Program. Date of last analysis was 1 July 2019. SETTING: Inpatient and outpatient genetics service at two large academic centres in Singapore. PATIENTS: Inclusion criteria: patients suspected of genetic disorders, based on abnormal antenatal ultrasound, multiple congenital anomalies and developmental delay. EXCLUSION CRITERIA: patients with known genetic disorders, either after clinical assessment or investigations (such as karyotype or chromosomal microarray). INTERVENTIONS: Use of NGS technology-whole exome sequencing (WES) or whole genome sequencing (WGS). MAIN OUTCOME MEASURES: (1) Diagnostic yield by sequencing type, (2) diagnostic yield by phenotypical categories, (3) reduction in time to diagnosis and (4) change in clinical outcomes and management. RESULTS: We demonstrate a 37.8% diagnostic yield for WES (n=172) and a 33.3% yield for WGS (n=24). The yield was higher when sequencing was conducted on trios (40.2%), as well as for certain phenotypes (neuromuscular, 54%, and skeletal dysplasia, 50%). In addition to aiding genetic counselling in 100% of the families, a positive result led to a change in treatment in 27% of patients. CONCLUSION: Genomic sequencing is an effective method for diagnosing rare disease or previous 'undiagnosed' disease. The clinical utility of WES/WGS is seen in the shortened time to diagnosis and the discovery of novel variants. Additionally, reaching a diagnosis significantly impacts families and leads to alteration in management of these patients.

Current Perspectives and Unmet Needs of Primary Immunodeficiency Care in Asia Pacific.

Background: The Asia Pacific Society for Immunodeficiencies (APSID) conducted nine primary immunodeficiency (PID) Schools in 5 years since inauguration to provide PID care training for early career physicians in Asia Pacific, a region with divergent needs in PID resources and training. Objective: To identify differences in PID patient care resource and training needs across Asia Pacific and propose a corresponding action plan. Methods: The Human Development Index (HDI) indicates the degree of socio-economic development in each country/region. Information related to investigations and learning issues were extracted from the abstracts and personal statements from all Schools and mapped onto resource and training needs. Correlations between HDI and country/region-specific parameters were tested by two-tailed Pearson correlation. Results: A total of 427 abstracts were received in nine Schools between 2015 and 2020, predominantly on immunodeficiencies affecting cellular and humoral immunity. Genetic confirmation was described in 61.8% of abstracts, and its absence negatively correlated with HDI (r = -0.696, p = 0.004). Essential immunologic and genetic tests were not available in 25.4 and 29.5% of abstracts, respectively, and their absence negatively correlated with HDI (r = -0.788, p < 0.001; r = -0.739, p = 0.002). HDI positively correlated with average testing level (r = 0.742, p = 0.002). Cases from medium-HDI countries/regions focused on learning how to investigate a patient for PIDs in cases of severe or atypical infections, whereas those from very-high-HDI countries/regions, from which most faculty members originated, listed hematopoietic stem cell transplantation and gene therapy, newborn screening, and research as learning issues more frequently. Conclusion: There are unique HDI-related PID resource and training needs in each country/region. APSID proposes HDI group-specific strategies to improve PID care and education in her member countries/regions. Further quantitative analysis of needs in PID care in Asia Pacific is needed for lobbying governments to increase their support for PID care and research.

Dominant-negative NFKBIA mutation promotes IL-1ß production causing hepatic disease with severe immunodeficiency.

Although IKK-ß has previously been shown as a negative regulator of IL-1ß secretion in mice, this role has not been proven in humans. Genetic studies of NF-κB signaling in humans with inherited diseases of the immune system have not demonstrated the relevance of the NF-κB pathway in suppressing IL-1ß expression. Here, we report an infant with a clinical pathology comprising neutrophil-mediated autoinflammation and recurrent bacterial infections. Whole-exome sequencing revealed a de novo heterozygous missense mutation of NFKBIA, resulting in a L34P IκBα variant that severely repressed NF-κB activation and downstream cytokine production. Paradoxically, IL-1ß secretion was elevated in the patient's stimulated leukocytes, in her induced pluripotent stem cell-derived macrophages, and in murine bone marrow-derived macrophages containing the L34P mutation. The patient's hypersecretion of IL-1ß correlated with activated neutrophilia and liver fibrosis with neutrophil accumulation. Hematopoietic stem cell transplantation reversed neutrophilia, restored a resting state in neutrophils, and normalized IL-1ß release from stimulated leukocytes. Additional therapeutic blockade of IL-1 ameliorated liver damage, while decreasing neutrophil activation and associated IL-1ß secretion. Our studies reveal a previously unrecognized role of human IκBα as an essential regulator of canonical NF-κB signaling in the prevention of neutrophil-dependent autoinflammatory diseases. These findings also highlight the therapeutic potential of IL-1 inhibitors in treating complications arising from systemic NF-κB inhibition.

Heterozygous missense variant in EIF6 gene: A novel form of Shwachman-Diamond syndrome?

Shwachman-Diamond syndrome (SDS) is a rare multisystem ribosomal biogenesis disorder characterized by exocrine pancreatic insufficiency, hematologic abnormalities and bony abnormalities. About 90% of patients have biallelic mutations in SBDS gene. Three additional genes-EFL1, DNAJC21 and SRP54 have been reported in association with a SDS phenotype. However, the cause remains unknown for ~10% of patients. Herein, we report a 6-year-old Chinese boy, who presented in the neonatal period with pancytopenia, liver transaminitis with hepatosplenomegaly and developmental delay, and subsequently developed pancreatic insufficiency complicated by malabsorption and poor growth. Exome sequencing identified a novel de novo heterozygous variant in EIF6 (c.182G>T, p.Arg61Leu). EIF6 protein inhibits ribosomal maturation and is removed in the late steps of ribosomal maturation by SBDS and EFL1 protein. Given the interaction of EIF6 with SBDS and EFL1, we postulate heterozygous variants in EIF6 as a novel cause of Shwachman-Diamond-like phenotype. We compared the phenotype of our patient with those in patients with mutation in SBDS, EFL1, DNAJC21, and SRP54 genes to support this association. Identification of more cases of this novel phenotype would strengthen the association with the genetic etiology.

DISSEMINATED BACILLUS-CALMETTE-GUÉRIN INFECTIONS AND PRIMARY IMMUNODEFICIENCY DISORDERS IN SINGAPORE: A SINGLE CENTER 15-YEAR RETROSPECTIVE REVIEW.

BACKGROUND: Disseminated Bacillus Calmette-Guérin (BCG) disease (BCGosis) is a classical feature of children with primary immunodeficiency disorders (PIDs). METHODS: A 15-year retrospective review was conducted in KK Women's and Children's Hospital in Singapore, from January 2003 to October 2017. RESULTS: Ten patients were identified, the majority male (60.0%). The median age at presentation of symptoms of BCG infections was 3.8 (0.8 - 7.4) months. All the patients had likely underlying PIDS - four with Severe Combined Immunodeficiency (SCID), three with Mendelian Susceptibility to Mycobacterial Diseases (MSMD), one with Anhidrotic Ectodermal Dysplasia with Primary Immunodeficiency (EDA-ID), one with combined immunodeficiency (CID), and one with STAT-1 gain-of-function mutation. Definitive BCGosis was confirmed in all patients by the identification of Mycobacterium bovis subsp BCG from microbiological cultures. The susceptibility profiles of Mycobacterium bovis subsp BCG are as follows: Rifampicin (88.9%), Isoniazid (44.47%), Ethambutol (100.0%), Streptomycin (100.0%), Kanamycin (100.0%), Ethionamide (25.0%), and Ofloxacin (100.0%). Four patients (40.0%) received a three-drug regimen. Five patients (50.0%) underwent hematopoietic stem cell transplant (HSCT), of which three (60%) have recovered. Overall mortality was 50.0%. CONCLUSION: Disseminated BCG disease (BCGosis) should prompt immunology evaluation to determine the diagnosis of the immune defect. A three-drug regimen is adequate for treatment if the patient undergoes early HSCT.

Juvenile-Onset Immunodeficiency Secondary to Anti-Interferon-Gamma Autoantibodies.

Immunodeficiency secondary to anti-interferon-gamma (anti-IFN-γ) autoantibodies was first described in 2004 as an acquired defect in the IFN-γ pathway leading to susceptibility to multiple opportunistic infections, including dimorphic fungi, parasites, and bacteria, especially tuberculosis and non-tuberculous mycobacterium (NTM) species. It has so far only been described in adult patients. We present 2 cases of disseminated NTM infections in otherwise immunocompetent children. A 16-year-old girl with Sweet's syndrome-like neutrophilic dermatosis developed recurrent fever and cervical lymphadenitis secondary to Mycobacterium abscessus. A 10-year-old boy with a history of prolonged fever, aseptic meningitis, aortitis, and arteritis in multiple blood vessels developed thoracic vertebral osteomyelitis secondary to Mycobacterium avium complex. Both patients were found to have positive serum neutralizing anti-IFNγ autoantibodies. Testing for anti-IFNγ autoantibodies should be considered in otherwise healthy immunocompetent hosts with recurrent or disseminated NTM infection. This represents a phenocopy of primary immunodeficiency which has been recently described only in adults. We report the first two cases of this phenomenon to affect children.

Family History of Early Infant Death Correlates with Earlier Age at Diagnosis But Not Shorter Time to Diagnosis for Severe Combined Immunodeficiency.

BACKGROUND: Severe combined immunodeficiency (SCID) is fatal unless treated with hematopoietic stem cell transplant. Delay in diagnosis is common without newborn screening. Family history of infant death due to infection or known SCID (FH) has been associated with earlier diagnosis. OBJECTIVE: The aim of this study was to identify the clinical features that affect age at diagnosis (AD) and time to the diagnosis of SCID. METHODS: From 2005 to 2016, 147 SCID patients were referred to the Asian Primary Immunodeficiency Network. Patients with genetic diagnosis, age at presentation (AP), and AD were selected for study. RESULTS: A total of 88 different SCID gene mutations were identified in 94 patients, including 49 IL2RG mutations, 12 RAG1 mutations, 8 RAG2 mutations, 7 JAK3 mutations, 4 DCLRE1C mutations, 4 IL7R mutations, 2 RFXANK mutations, and 2 ADA mutations. A total of 29 mutations were previously unreported. Eighty-three of the 94 patients fulfilled the selection criteria. Their median AD was 4 months, and the time to diagnosis was 2 months. The commonest SCID was X-linked (n = 57). A total of 29 patients had a positive FH. Candidiasis (n = 27) and bacillus Calmette-Guérin (BCG) vaccine infection (n = 19) were the commonest infections. The median age for candidiasis and BCG infection documented were 3 months and 4 months, respectively. The median absolute lymphocyte count (ALC) was 1.05 × 109/L with over 88% patients below 3 × 109/L. Positive FH was associated with earlier AP by 1 month (p = 0.002) and diagnosis by 2 months (p = 0.008), but not shorter time to diagnosis (p = 0.494). Candidiasis was associated with later AD by 2 months (p = 0.008) and longer time to diagnosis by 0.55 months (p = 0.003). BCG infections were not associated with age or time to diagnosis. CONCLUSION: FH was useful to aid earlier diagnosis but was overlooked by clinicians and not by parents. Similarly, typical clinical features of SCID were not recognized by clinicians to shorten the time to diagnosis. We suggest that lymphocyte subset should be performed for any infant with one or more of the following four clinical features: FH, candidiasis, BCG infections, and ALC below 3 × 109/L.

Incidentalome from Genomic Sequencing: A Barrier to Personalized Medicine?

BACKGROUND: In Western cohorts, the prevalence of incidental findings (IFs) or incidentalome, referring to variants in genes that are unrelated to the patient's primary condition, is between 0.86% and 8.8%. However, data on prevalence and type of IFs in Asian population is lacking. METHODS: In 2 cohorts of individuals with genomic sequencing performed in Singapore (total n = 377), we extracted and annotated variants in the 56 ACMG-recommended genes and filtered these variants based on the level of pathogenicity. We then analyzed the precise distribution of IFs, class of genes, related medical conditions, and potential clinical impact. RESULTS: We found a total of 41,607 variants in the 56 genes in our cohort of 377 individuals. After filtering for rare and coding variants, we identified 14 potential variants. After reviewing primary literature, only 4 out of the 14 variants were classified to be pathogenic, while an additional two variants were classified as likely pathogenic. Overall, the cumulative prevalence of IFs (pathogenic and likely pathogenic variants) in our cohort was 1.6%. CONCLUSION: The cumulative prevalence of IFs through genomic sequencing is low and the incidentalome may not be a significant barrier to implementation of genomics for personalized medicine.

Pilot study of the use of Yin Qiao San in children with conventional antipyretic hypersensitivity.

BACKGROUND: Children with a diagnosis of cross-reactive hypersensitivity to both paracetamol and nonsteroidal anti-inflammatory drugs are limited in their choice of antipyretics. OBJECTIVE: The aim of this pilot study is to evaluate the feasibility of using a Chinese proprietary medicine, Yin Qiao San (YQS), for fever relief. METHODS: A single centre, open label, prospective clinical trial exploring the tolerability and feasibility of using YQS for fever relief in children who are unable to use conventional antipyretic medications. Children between 1-18 years of age with hypersensitivity to multiple antipyretics were recruited. Eligible participants underwent an oral provocation test with YQS. Children who passed the oral provocation test were instructed to take a prescribed dose of YQS when the temperature was >38.0℃ and continued till the fever settled. Time taken for fever resolution and any adverse events were collected. RESULTS: A total of 21 children, mean age 10.7 years, had a diagnosis of paracetamol and ibuprofen hypersensitivity. All except one patient successfully tolerated an oral challenge of YQS. Of the 88 doses of YQS taken for fever over 38.0℃, 16 (18%) had documented temperature reduction 2 hours after ingestion and 30 (34%) had documented temperature reduction 4 hours after ingestion. There were 2 reports of urticaria after YQS use which were attributed to flare of recurrent spontaneous urticaria during the illness. None of the patients developed symptoms of circulatory compromise or respiratory distress. CONCLUSION: YQS is generally well tolerated in patients with paracetamol and ibuprofen hypersensitivity.

Tricho-hepato-enteric syndrome (THE-S): two cases and review of the literature.

UNLABELLED: Tricho-hepato-enteric syndrome (THE-S) is characterized by severe infantile diarrhea, failure to thrive, dysmorphism, woolly hair, and immune or hepatic dysfunction. We report two cases of East Asian descent with THE-S who had remained undiagnosed despite extensive investigations but were diagnosed on whole exome sequencing (WES). Both cases presented with chronic diarrhea, failure to thrive, and recurrent infections. Case 1 had posteriorly rotated low set ears, mild retrognathia, and fine curly hypopigmented hair. She was managed with prolonged total parenteral nutrition and intravenous immunoglobulin infusions. Case 2 had sparse coarse brown hair as well as multiple lentigines and café-au-lait macules. She was managed with amino acid-based formula. For both cases, routine investigations were inconclusive. WES in both cases showed biallelic truncating mutations in TTC37 (c.3507T>G;p.Y1169X and c.3601C>T;p.R1201X in case 1 and c.3507T>G;p.Y1169X and c.154G>T;p.E52X in case 2), suggesting a diagnosis of THE-S. CONCLUSION: We present novel mutations in the TTC37 gene in two individuals of East Asian descent with the rare THE-S, detected by WES. Future identification of patients with THE-S and establishing genotype-phenotype correlations will aid in counseling the patients and their families. WHAT IS KNOWN: • Tricho-Hepato-Enteric syndrome (THE-S) is characterized by severe infantile diarrhea, failure to thrive, dysmorphism, woolly hair, and immune or hepatic dysfunction. • Complex patients with diagnostic dilemmas undergo extensive investigations. What is New: • This is a report of novel mutations in TTC37 in individuals of East Asian descent. • Whole exome sequencing (WES) can be useful in certain complex cases with diagnostic dilemmas.

Investigations into an outbreak of suppurative lymphadenitis with BCG vaccine SSI(®) in Singapore.

INTRODUCTION: From 2011 to 2012, we received an unexpectedly high number of reports of suppurative lymphadenitis following administration of a BCG vaccine used in our childhood vaccination programme in Singapore. We sought to determine the local incidence rates of BCG-associated suppurative lymphadenitis across the 2009 to 2012 vaccinated cohorts, and to analyse the potential factors contributing to this outbreak. METHODS: Reports of lymphadenitis following BCG vaccination from an AEFI active surveillance system at the KK Women's and Children's Hospital (KKH) and passive surveillance data from other healthcare institutions were reviewed. All valid reports received from January 2009 to December 2013 involving neonates vaccinated with the BCG vaccine in 2009 to 2012 that met case definitions were included in our analysis. Details of the demographics and vaccination history of the child, and statistics from the local vaccination programme were also obtained. Potential contributory factors were selected for further investigation based on a literature review of similar outbreaks overseas. RESULTS: We identified 283 cases of lymphadenitis, of which 76% were suppurative. A spike in suppurative lymphadenitis cases was seen in the 2011 vaccinated cohort, with an incidence rate of 3.16 per 1000 vaccinees, as compared to 0.71 to 0.85 per 1000 in the 2009, 2010 and 2012 cohorts. Our investigations identified the likely cause of the outbreak to be batch-related, arising from manufacturing issues encountered by the manufacturer, after ruling out vaccine administration-related and host-related factors. CONCLUSIONS: The three-fold spike in BCG-associated suppurative lymphadenitis cases observed in the 2011 vaccinated cohort, possibly due to batch-to-batch variation of the vaccine, highlights that manufacturing controls can continue to be a challenge. Development of a more sensitive assay to test the reactogenicity of the BCG vaccine may help reduce the occurrence of such outbreaks and improve public confidence in the nation's vaccination programme.

Active surveillance of adverse events following childhood immunization in Singapore.

INTRODUCTION: In Singapore, reporting of adverse events following immunization (AEFI) was historically passive. In 2009, Health Sciences Authority collaborated with KK Women's and Children's Hospital to perform active surveillance for AEFI. We report the methodology and initial findings of this surveillance following childhood vaccines. METHODS: From April 2010 to March 2012, we screened all paediatric admissions for possible relationships to vaccination, excluding elective admissions, and performed causality assessment for each case using standardized definitions for certain, probable, possible and unlikely. Baseline demographics, data on implicated vaccines and clinical details including severity and outcomes were collected. Total hospital admissions were used to calculate rates of AEFI. RESULTS: We screened 45,571 (80%) of 56,526 admissions, and evaluated 1988 (4.4%) children. Median age at presentation was 3.1 months, while median interval from vaccination to symptom onset was 6 days. There were 311 (15.6%) children with AEFI that were considered possibly, probably or certainly associated with vaccines. However, 98.8% recovered without any long-term sequelae. The hospital-based active surveillance of AEFI enabled the detection of a 5-fold increase (95% CI 1.2-33.1) in BCG-associated regional lymphadenitis in April 2010, which triggered follow-up safety analysis to guide public health advice. CONCLUSIONS: Hospital-based active surveillance can enhance signal detection and follow-up investigations of AEFI. Subsequently, public health bodies are better equipped to maintain public confidence in vaccination programmes and physicians are able to provide relevant advice to parents. It also allows for a better understanding of risk-benefit ratios of specific vaccines and aids the generation of public health vaccination policy.

Gum pigmentation: an unusual adverse effect of sublingual immunotherapy

Sublingual immunotherapy has gained acceptance amongst the paediatric community as it is very well tolerated and is safe. The adverse effects of this therapy is minimal consisting mainly of local side effects within the oral cavity such as itching of the mouth, swelling of the lips and less frequently abdominal pain, wheezing and urticaria has been described. This report is to highlight another local side effect of sublingual immunotherapy which has been observed in 3 of our patients. This is pigmentation of the gums which can occur anytime during the course of the immunotherapy. It resolves on stopping the immunotherapy and is likely due to a local inflammatory process occurring in the gums of these children. There is no associated pain or itching with the pigmentation. It can persist as long as the child is on the immunotherapy.