Decrease in hospital admissions for febrile seizures and reports of hypotonic-hyporesponsive episodes presenting to hospital emergency departments since switching to acellular pertussis vaccine in Canada: a report from IMPACT

Do vaccines cause epilepsy? Review of cases in the National Vaccine Injury Compensation Program

OBJECTIVE

The National Childhood Vaccine Injury Act of 1986 created the National Vaccine Injury Compensation Program (VICP), a no-fault alternative to the traditional tort system. Since 1988, the total compensation paid exceeds $5 billion. Although epilepsy is one of the leading reasons for filing a claim, there has been no review of the process and validity of the legal outcomes given current medical information. The objectives were to review the evolution of the VICP program in regard to vaccine-related epilepsy and assess the rationale behind decisions made by the court.

METHODS

Publicly available cases involving epilepsy claims in the VICP were searched through Westlaw and the US Court of Federal Claims websites. All published reports were reviewed for petitioner's theories supporting vaccine-induced epilepsy, respondent's counterarguments, the final decision regarding compensation, and the rationale underlying these decisions. The primary goal was to determine which factors went into decisions regarding whether vaccines caused epilepsy.

RESULTS

Since the first epilepsy case in 1989, there have been many changes in the program, including the removal of residual seizure disorder as a vaccine-related injury, publication of the Althen prongs, release of the acellular form of pertussis, and recognition that in genetic conditions the underlying genetic abnormality rather than the immunization causes epilepsy. We identified 532 unique cases with epilepsy: 105 with infantile spasms and 427 with epilepsy without infantile spasms. The petitioners' experts often espoused outdated, erroneous causation theories that lacked an acceptable medical or scientific foundation and were frequently criticized by the court.

SIGNIFICANCE

Despite the lack of epidemiological or mechanistic evidence indicating that childhood vaccines covered by the VICP result in or aggravate epilepsy, these cases continue to be adjudicated. After 35 years of intense litigation, it is time to reconsider whether epilepsy should continue to be a compensable vaccine-induced injury.

Infant vaccination against pertussis in Argentina: Parent-reported outcomes on reactogenicity, impact on daily routine and satisfaction after pentavalent whole-cell or hexavalent acellular pertussis vaccines

Introduction

In Argentina, a pentavalent whole-cell pertussis vaccine (wP) is used in the National Immunization Program, however hexavalent acellular pertussis (aP) vaccines are available in the private market.

Objective

To describe parent or guardianś perceptions on reactogenicity, daily routine and satisfaction after a first or third dose of a wP-pentavalent plus IPV (wP-group) or the fully-liquid aP-hexavalent vaccine (aP-group) in infants.

Material and methods

This was a prospective observational and analytical study. Parents or guardians of infants born at term attending a public or private vaccination center in Buenos Aires City were invited to participate. All parents or guardians had completed 12-year schooling and were asked to fill out an online 7-day post vaccination questionnaire. The questionnaire was validated as the first phase of the study. Descriptive analysis of study variables was carried out, REDCap was used for the online survey, and STATA 14 for data analysis.

Results

1071 parents or guardians answered the questionnaire (response rate 82%), 530 for wP-group and 541 for aP-group.Local and systemic adverse reactions, in groups wP and aP respectively, were: pain 83%, 28%; swelling 63%, 16%; redness 52%, 22%; irritability 72%, 52%; fever 37%, 8%; loss of appetite 36%, 19%; drowsiness 38%, 27%; and vomiting 15%, 11%.Impact on daily life: social activities 36%, 20%; routine 48%, 24%; mood 39%, 23%; vitality 47%, 24%; sleep 50%, 30%; and appetite 22%, 7%.Parents were satisfied with the vaccination process in 96% and 98% for wP-group and aP-group respectively. Parents reported willingness to bring infant for future vaccine doses in 97% and 99% for wP-group and aP-group respectively.

Conclusions

Reported reactogenicity and impact on family daily routine was higher in infants receiving wP-pentavalent than aP-hexavalent vaccines. Parents in both groups conveyed vaccine acceptance and positive intentions for future immunizations.

DTaP-IPV-HB-Hib vaccine (Hexaxim): an update 10 years after first licensure

INTRODUCTION

Hexaxim® is fully liquid, hexavalent, combination vaccine that provides immunization against diphtheria, tetanus, pertussis (whooping cough), polio, hepatitis B, and invasive diseases caused by Haemophilus influenzae type b. Combination vaccines such as Hexaxim reduce the number of injections needed, improving both vaccination compliance and operational efficiency.

AREAS COVERED

Safety and immunogenicity data were reviewed from >25 clinical trials involving approximately 7200 infants/toddlers, identified using PubMed searches to April 2023. These trials have evaluated a diverse range of primary series and booster schedules, including antibody persistence, co-administration of Hexaxim with other routine pediatric vaccines, and specific populations (born to Tdap-vaccinated women, preterm, and immunocompromised infants). Lastly, post-marketing surveillance and real-world effectiveness data were assessed.

EXPERT OPINION

An extensive program of clinical development prior to licensure demonstrated favorable vaccine safety and good immunogenicity of each antigen, and Hexaxim was first approved for use in 2012. In the 10 years since licensure, Hexaxim has been adopted widely, with more than 180 million doses distributed worldwide. The widespread use of this hexavalent vaccine is a crucial tool in the ongoing and future control of six pediatric infectious diseases globally.

Seizures after vaccines

Immunization plays an important role in achieving global health goals. Thus, vaccination is one of the essential means of preventing infectious and viral diseases. The onset of adverse events following immunization (AEFI) is common and most of the time it is a mild effect. However, stimulating the immune system during critical periods of brain development can lead to neurological effects. Among the neurological effects, we were interested in this work by seizures appearing following vaccination.

Vaccination and childhood epilepsies

INTRODUCTION

The evidence relating vaccination to febrile seizures and epilepsy is evaluated with an emphasis on febrile seizures (FS), Dravet syndrome (DS), West syndrome, and other developmental and epileptic encephalopathies.

METHODS

A systematic literature review using search words vaccination/immunization AND febrile seizures/epilepsy/Dravet/epileptic encephalopathy/developmental encephalopathy was performed. The role of vaccination as the cause/trigger/aggravation factor for FS or epilepsies and preventive measures were analyzed.

RESULTS

From 1428 results, 846 duplicates and 447 irrelevant articles were eliminated; 120 were analyzed.

CONCLUSIONS

There is no evidence that vaccinations cause epilepsy in healthy populations. Vaccinations do not cause epileptic encephalopathies but may be non-specific triggers to seizures in underlying structural or genetic etiologies. The first seizure in DS may be earlier in vaccinated versus non-vaccinated patients, but developmental outcome is similar in both groups. Children with a personal or family history of FS or epilepsy should receive all routine vaccinations. This recommendation includes DS. The known risks of the infectious diseases prevented by immunization are well established. Vaccination should be deferred in case of acute illness. Acellular pertussis DTaP (diphtheria-tetanus-pertussis) is recommended. The combination of certain vaccine types may increase the risk of febrile seizures however the public health benefit of separating immunizations has not been proven. Measles-containing vaccine should be administered at age 12-15 months. Routine prophylactic antipyretics are not indicated, as there is no evidence of decreased FS risk and they can attenuate the antibody response following vaccination. Prophylactic measures (preventive antipyretic medication) are recommended in DS due to the increased risk of prolonged seizures with fever.

Cost-Minimization and Budget Impact Analysis of a Hexavalent Vaccine (Hexaxim®) in the Colombian Expanded Program on Immunization

OBJECTIVES

To evaluate cost implications of a hexavalent vaccine (diphtheria, tetanus, and acellular pertussis [DTaP]-inactivated polio vaccine [IPV]-hepatitis B [HB]-Haemophilus influenzae type B [Hib] polysaccharide conjugated to T protein [PRP∼T]) as an alternative to DT-whole-cell pertussis (wP)-HB//Hib, DTwP, IPV, and oral polio vaccines in the Expanded Program on Immunization schedule in Colombia.

METHODS

Primary vaccination (DTaP-IPV-HB-PRP∼T or DTwP-HB-Hib + IPV [2, 4, 6 months]) and booster (DTaP-IPV-HB-PRP∼T or DTwP + oral polio vaccine [18 months]) (scenario 1) and primary vaccination only (DTaP-IPV-HB-PRP∼T or DTwP-HB-Hib + IPV) (scenario 2) were evaluated. An estimated cost-minimization analysis was based on a micro costing technique for vaccination-associated activities. Adverse event (AE)-associated costs, out-of-pocket costs, and productivity losses for caregivers were included. A budget impact (12-month temporal horizon) was estimated according to the distribution of full-term and premature infants. A 5% annual discount rate was used. A 2-way univariate (tornado) analysis evaluated which variables had the greatest impact on the overall cost.

RESULTS

DTaP-IPV-HB-PRP∼T resulted in a cost increase of 29.38% (scenario 1) and 22.19% (scenario 2) for full-term infants and a decrease of 0.99% (scenario 1) and 18.88% (scenario 2) for premature infants, probably because of the higher incidence of wP-related AEs and associated costs in premature infants. With a 100% replacement rate, the budget impact for full-term infants and full-term plus premature infants was 0.2373% and 0.2180% (scenario 1), respectively, and 0.1302% and 0.1114% (scenario 2), respectively, of the national immunization program budget. The variables with most impact were the hexavalent vaccine price and costs associated with the pentavalent safety profile.

CONCLUSIONS

Incorporation of the hexavalent vaccine in the Expanded Program on Immunization schedule would lead to an increase in spending largely mitigated by reduced AE incidence and reduced logistic and social costs.

Active surveillance of acute paediatric hospitalisations demonstrates the impact of vaccination programmes and informs vaccine policy in Canada and Australia

Sentinel surveillance of acute hospitalisations in response to infectious disease emergencies such as the 2009 influenza A(H1N1)pdm09 pandemic is well described, but recognition of its potential to supplement routine public health surveillance and provide scalability for emergency responses has been limited. We summarise the achievements of two national paediatric hospital surveillance networks relevant to vaccine programmes and emerging infectious diseases in Canada (Canadian Immunization Monitoring Program Active; IMPACT from 1991) and Australia (Paediatric Active Enhanced Disease Surveillance; PAEDS from 2007) and discuss opportunities and challenges in applying their model to other contexts. Both networks were established to enhance capacity to measure vaccine preventable disease burden, vaccine programme impact, and safety, with their scope occasionally being increased with emerging infectious diseases’ surveillance. Their active surveillance has increased data accuracy and utility for syndromic conditions (e.g. encephalitis), pathogen-specific diseases (e.g. pertussis, rotavirus, influenza), and adverse events following immunisation (e.g. febrile seizure), enabled correlation of biological specimens with clinical context and supported responses to emerging infections (e.g. pandemic influenza, parechovirus, COVID-19). The demonstrated long-term value of continuous, rather than incident-related, operation of these networks in strengthening routine surveillance, bridging research gaps, and providing scalable public health response, supports their applicability to other countries.

Active Surveillance of Adverse Events Following Human Papillomavirus Vaccination: Feasibility Pilot Study Based on the Regional Health Care Information Platform in the City of Ningbo, China

BACKGROUND

Comprehensive safety data for vaccines from post-licensure surveillance, especially active surveillance, could guide administrations and individuals to make reasonable decisions on vaccination. Therefore, we designed a pilot study to assess the capability of a regional health care information platform to actively monitor the safety of a newly licensed vaccine.

OBJECTIVE

This study aimed to conduct active surveillance of human papillomavirus (HPV) vaccine safety based on this information platform.

METHODS

In 2017, one of China's most mature information platforms with superior data linkage was selected. A structured questionnaire and open-ended interview guidelines were developed to investigate the feasibility of active surveillance following HPV vaccination using the regional health care information platform in Ningbo. The questionnaire was sent to participants via email, and a face-to-face interview was conducted to confirm details or resolve discrepancies.

RESULTS

Five databases that could be considered essential to active surveillance of vaccine safety were integrated into the platform starting in 2015. Except for residents' health records, which had a coverage rate of 87%, the data sources covered more than 95% of the records that were documented in Ningbo. All the data could be inherently linked using the national identity card. There were 19,328 women who received the HPV vaccine, and 37,988 doses were administered in 2017 and 2018. Women aged 30-40 years accounted for the largest proportion. Quadrivalent vaccination accounted for 73.1% of total vaccination, a much higher proportion than that of bivalent vaccination. Of the first doses, 60 (60/19,328, 0.31%) occurred outside Ningbo. There were no missing data for vaccination-relevant variables, such as identity card, vaccine name, vaccination doses, vaccination date, and manufacturer. ICD-10 coding could be used to identify 9,180 cases using a predefined list of the outcomes of interest, and 1.88% of these cases were missing the identity card. During the 90 days following HPV vaccination, 4 incident cases were found through the linked vaccination history and electronic medical records. The combined incident rate of rheumatoid arthritis, optic neuritis, and Henoch-Schonlein purpura was 8.84/100,000 doses of bivalent HPV, and the incidence rate of rheumatoid arthritis was 3.75/100,000 doses of quadrivalent HPV.

CONCLUSIONS

This study presents an available approach to initiate an active surveillance system for adverse events following HPV vaccination, based on a regional health care information platform in China. An extended observation period or the inclusion of additional functional sites is warranted to conduct future hypothesis-generating and hypothesis-confirming studies for vaccine safety concerns.

SCN1A Variants in vaccine-related febrile seizures: A prospective study

OBJECTIVE

Febrile seizures may follow vaccination. Common variants in the sodium channel gene, SCN1A, are associated with febrile seizures, and rare pathogenic variants in SCN1A cause the severe developmental and epileptic encephalopathy Dravet syndrome. Following vaccination, febrile seizures may raise the specter of poor outcome and inappropriately implicate vaccination as the cause. We aimed to determine the prevalence of SCN1A variants in children having their first febrile seizure either proximal to vaccination or unrelated to vaccination compared to controls.

METHODS

We performed SCN1A sequencing, blind to clinical category, in a prospective cohort of children presenting with their first febrile seizure as vaccine proximate (n = 69) or as non-vaccine proximate (n = 75), and children with no history of seizures (n = 90) recruited in Australian pediatric hospitals.

RESULTS

We detected 2 pathogenic variants in vaccine-proximate cases (p.R568X and p.W932R), both of whom developed Dravet syndrome, and 1 in a non-vaccine-proximate case (p.V947L) who had febrile seizures plus from 9 months. All had generalized tonic-clonic seizures lasting >15 minutes. We also found enrichment of a reported risk allele, rs6432860-T, in children with febrile seizures compared to controls (odds ratio = 1.91, 95% confidence interval = 1.31-2.81).

INTERPRETATION

Pathogenic SCN1A variants may be identified in infants with vaccine-proximate febrile seizures. As early diagnosis of Dravet syndrome is essential for optimal management and outcome, SCN1A sequencing in infants with prolonged febrile seizures, proximate to vaccination, should become routine. ANN NEUROL 2020;87:281-288.

Prevention of Pertussis, Tetanus, and Diphtheria with Vaccines in the United States: Recommendations of the Advisory Committee on Immunization Practices (ACIP)

This report compiles and summarizes all recommendations from CDC's Advisory Committee on Immunization Practices (ACIP) regarding prevention and control of tetanus, diphtheria, and pertussis in the United States. As a comprehensive summary of previously published recommendations, this report does not contain any new recommendations and replaces all previously published reports and policy notes; it is intended for use by clinicians and public health providers as a resource. ACIP recommends routine vaccination for tetanus, diphtheria, and pertussis. Infants and young children are recommended to receive a 5-dose series of diphtheria and tetanus toxoids and acellular pertussis (DTaP) vaccines, with one adolescent booster dose of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine. Adults who have never received Tdap also are recommended to receive a booster dose of Tdap. Women are recommended to receive a dose of Tdap during each pregnancy, which should be administered from 27 through 36 weeks’ gestation, regardless of previous receipt of Tdap. After receipt of Tdap, adolescents and adults are recommended to receive a booster tetanus and diphtheria toxoids (Td) vaccine every 10 years to assure ongoing protection against tetanus and diphtheria.

Bordetella pertussis

Pertussis is a highly infectious vaccine-preventable cough illness that continues to be a significant source of morbidity and mortality around the world. The majority of human illness is caused by Bordetella pertussis, and some is caused by Bordetella parapertussis. Bordetella is a Gram-negative, pleomorphic, aerobic coccobacillus. In the past several years, even countries with high immunization rates in early childhood have experienced rises in pertussis cases. Reasons for the resurgence of reported pertussis may include molecular changes in the organism and increased awareness and diagnostic capabilities, as well as lessened vaccine efficacy and waning immunity. The most morbidity and mortality with pertussis infection is seen in infants too young to benefit from immunization. Severe infection requiring hospitalization, including in an intensive care setting, is mostly seen in those under 3 months of age. As a result, research and public health actions have been aimed at better understanding and reducing the spread of Bordetella pertussis. Studies comparing the cost benefit of cocooning strategies versus immunization of pregnant women have been favorable towards immunizing pregnant women. This strategy is expected to prevent a larger number of pertussis cases, hospitalizations, and deaths in infants <1 year old while also being cost-effective. Studies have demonstrated that the source of infection in infants usually is a family member. Efforts to immunize children and adults, in particular pregnant women, need to remain strong.

Immunizing Patients With Adverse Events After Immunization and Potential Contraindications to Immunization: A Report From the Special Immunization Clinics Network

BACKGROUND

For patients who have experienced adverse events following immunization (AEFI) or who have specific medical conditions, there is limited evidence regarding the best approach to immunization. The Special Immunization Clinics (SICs) Network was established to standardize patient management and assess outcomes after reimmunization. The study objective was to describe the first 2 years of the network's implementation.

METHODS

Twelve SICs were established across Canada by infectious diseases specialists and allergists. Inclusion criteria were as follows: local reaction ≥ 10 cm, allergic symptoms < 24 hours postimmunization, neurologic symptoms and other AEFI or medical conditions of concern. Eligible patients underwent a standardized evaluation, causality assessment was performed, immunization recommendations were made by expert physicians and patients were followed up to capture AEFI. After individual consent, data were transferred to a central database for analysis.

RESULTS

From June 2013 to May 2015, 151 patients were enrolled. Most were referred for prior AEFI (132/151, 87%): 42 (32%) for allergic-like reactions, 31 (23%) for injection-site reactions, 20 (15%) for neurologic symptoms and 39 (30%) for other systemic symptoms. Nineteen patients (13%) were seen for underlying conditions that complicated immunization. Reimmunization was recommended for 109 patients, 60 of whom (55%) were immunized and followed up. Eleven patients (18%) experienced recurrence of their AEFI; none were serious (eg, resulting in hospitalization, permanent disability or death).

CONCLUSIONS

The most frequent reasons for referral to a SIC were allergic-like events and injection site reactions. Reimmunization was safe in most patients. Larger studies are needed to determine outcomes for specific types of AEFI.

Effect of vaccinations on seizure risk and disease course in Dravet syndrome

OBJECTIVE

To study the effect of vaccination-associated seizure onset on disease course and estimate the risk of subsequent seizures after infant pertussis combination and measles, mumps, and rubella (MMR) vaccinations in Dravet syndrome (DS).

METHODS

We retrospectively analyzed data from hospital medical files, child health clinics, and the vaccination register for children with DS and pathogenic SCN1A mutations. Seizures within 24 hours after infant whole-cell, acellular, or nonpertussis combination vaccination or within 5 to 12 days after MMR vaccination were defined as "vaccination-associated." Risks of vaccination-associated seizures for the different vaccines were analyzed in univariable and in multivariable logistic regression for pertussis combination vaccines and by a self-controlled case series analysis using parental seizure registries for MMR vaccines. Disease courses of children with and without vaccination-associated seizure onset were compared.

RESULTS

Children who had DS (n = 77) with and without vaccination-associated seizure onset (21% and 79%, respectively) differed in age at first seizure (median 3.7 vs 6.1 months, p < 0.001) but not in age at first nonvaccination-associated seizure, age at first report of developmental delay, or cognitive outcome. The risk of subsequent vaccination-associated seizures was significantly lower for acellular pertussis (9%; odds ratio 0.18, 95% confidence interval [CI] 0.05-0.71) and nonpertussis (8%; odds ratio 0.11, 95% CI 0.02-0.59) than whole-cell pertussis (37%; reference) vaccines. Self-controlled case series analysis showed an increased incidence rate ratio of seizures of 2.3 (95% CI 1.5-3.4) within the risk period of 5 to 12 days following MMR vaccination.

CONCLUSIONS

Our results suggest that vaccination-associated earlier seizure onset does not alter disease course in DS, while the risk of subsequent vaccination-associated seizures is probably vaccine-specific.

The Canadian Immunization Monitoring Program, ACTive (IMPACT): Active surveillance for vaccine adverse events and vaccine-preventable diseases

For almost 25 years the Canadian Immunization Monitoring Program, ACTive (IMPACT) has been conducting active surveillance for severe adverse events following immunization (AEFIs) and vaccine-preventable diseases in children. The network, which consists of volunteer paediatric infectious diseases investigators at 12 tertiary care paediatric hospitals, is an important component of Canada's AEFI monitoring. The network employs nurses at each of the sites to search for and report possible AEFIs to local, provincial and national public health authorities. The active nature of the surveillance ensures a high level of vigilance for severe AEFIs in children.

A combined diphtheria, tetanus, five-component acellular pertussis, poliovirus andHaemophilus influenzaetype b vaccine

Ideally, combination vaccines should not only be safe and effective, but also integrate smoothly into the vaccination schedule and provide advantages over the use of separately administered vaccines. Pentaceltrade mark (Sanofi Pasteur Ltd., Toronto, Canada), a combination vaccine first licensed in Canada and subsequently in other countries, is immunogenic against diphtheria, tetanus, pertussis, polio and Haemophilus influenzae type b when administered at 2, 4, 6 and 15-18 months of age. In published studies, the safety, immunogenicity and effectiveness of this combination vaccine were comparable with those of separately administered vaccines, with the advantage of a simplified dosing schedule.

Epilepsy and vaccinations: Italian guidelines

Reports of childhood epilepsies in temporal association with vaccination have had a great impact on the acceptance of vaccination programs by health care providers, but little is known about this possible temporal association and about the types of seizures following vaccinations. For these reasons the Italian League Against Epilepsy (LICE), in collaboration with other Italian scientific societies, has decided to generate Guidelines on Vaccinations and Epilepsy. The aim of Guidelines on Vaccinations and Epilepsy is to present recent unequivocal evidence from published reports on the possible relationship between vaccines and epilepsy in order to provide information about contraindications and risks of vaccinations in patients with epilepsy. The following main issues have been addressed: (1) whether contraindications to vaccinations exist in patients with febrile convulsions, epilepsy, and/or epileptic encephalopathies; and (2) whether any vaccinations can cause febrile seizures, epilepsy, and/or epileptic encephalopathies. Diphtheria-tetanus-pertussis (DTP) vaccination and measles, mumps, and rubella vaccination (MMR) increase significantly the risk of febrile seizures. Recent observations and data about the relationships between vaccination and epileptic encephalopathy show that some cases of apparent vaccine-induced encephalopathy could in fact be caused by an inherent genetic defect with no causal relationship with vaccination.

Vaccinations for healthcare personnel: update on influenza, hepatitis B, and pertussis

PURPOSE OF REVIEW

Healthcare personnel (HCP) are at risk for exposure to and transmission of potentially life-threatening vaccine preventable diseases to patients and colleagues. The Centers for Disease Control and Advisory Committee on Immunization Practices (ACIP) recommend routine influenza immunization and maintenance of immunity to hepatitis B and pertussis, among others. In this article, we aim to review recently approved influenza vaccines, as well as address some of the issues regarding hepatitis B and pertussis vaccinations in HCP.

RECENT FINDINGS

Several new formulations of influenza vaccines are now available, including quadrivalent vaccines and non-egg-based vaccines; their use in HCP requires further study. An alarming rise in pertussis rates has led to a revision of ACIP guidelines recommending vaccination for women during each pregnancy. Persistent lack of immunity to hepatitis B after vaccine series remains a problem for many HCP.

SUMMARY

Inactivated trivalent influenza vaccines remain the safest and most widely studied influenza vaccinations for healthcare workers. A pertussis booster in the form of Tdap is now recommended for most HCP. More studies are needed regarding the issue of nonresponders in HCP who receive the three-dose hepatitis B vaccine series, as there are some promising strategies available that may boost immune responses.

Applicability of the Brighton Collaboration Case Definition for seizure after immunization in active and passive surveillance in Canada

BACKGROUND

The Canadian Adverse Event Following Immunization Surveillance System (CAEFISS) receives reports via active syndromic surveillance for selected serious AEFI from the Canadian Immunization Monitoring Program Active (IMPACT) and via targeted passive surveillance from Federal/Provincial/Territorial health jurisdictions. Post-immunization seizure is a target of active and passive surveillance. Since 2009, the revised national AEFI reporting forms enable capture of terms specific to several Brighton Collaboration Case Definitions (BCCD) including generalized seizure and fever.

OBJECTIVE

To evaluate feasibility of applying the BCCD for generalized seizure to adverse event following immunization (AEFI) reports collected by IMPACT and targeted passive surveillance (non-IMPACT).

METHODS

Reports to CAEFISS coded as seizure in children <2 years of age (vaccination dates 1998-2011) were reviewed retrospectively. A BCCD level (1-5 or unclassifiable) was assigned. The effects of reporting source (IMPACT versus non-IMPACT), seriousness [serious (e.g., hospitalized) versus non-serious], vaccination year (1998-2008 versus 2009-2011), and data submission method to CAEFISS (electronic versus paper) were assessed by stratified analysis.

RESULTS

There were 459 IMPACT and 908 non-IMPACT cases analyzed, of which 99.6% and 27%, respectively, were serious reports. The revised reporting form that captured the BCCD components (2009-2011) was associated with increased proportions of IMPACT and non-IMPACT cases meeting the BCCD for generalized seizure.

CONCLUSIONS

Incorporating the BCCD components (level of consciousness, motor manifestations and fever ≥38°C) into the national reporting form and guidelines appeared to improve the feasibility of their use in AEFI surveillance. This effect was more pronounced among active syndromic surveillance compared to targeted passive surveillance reports.

Safety and immunogenicity of an investigational fully liquid hexavalent DTaP-IPV-Hep B-PRP-T vaccine at two, four and six months of age compared with licensed vaccines in Latin America

OBJECTIVE

This trial assessed the safety of a fully liquid investigational hexavalent DTaP-IPV-Hep B-PRP-T vaccine containing 10 μg Hansenula polymorpha-derived recombinant hepatitis B (hep B) antigen for primary vaccination of infants at 2, 4 and 6 months of age compared with licensed comparators.

METHODS

Participants received the DTaP-IPV-Hep B-PRP-T vaccine (group 1, N = 1422) or licensed DTwP-Hep B//Hib (Tritanrix-Hep B/Hib) and oral poliovirus vaccines (group 2, N = 711). The incidence of severe fever (≥ 39.6°C rectal equivalent) in the 2 groups was compared statistically; reactogenicity was evaluated from parental reports. Anti-Hep B antibody titers were measured in a subset of participants (no hepatitis B vaccination at birth) 1 month after dose 3.

RESULTS

The investigational vaccine was well tolerated. After any dose, fever (rectal equivalent temperature ≥ 38°C) was observed in 74.8% and 92.7% of participants in groups 1 and 2; severe fever was observed in 4.0% and 5.5% of participants. Solicited injection site and systemic reactions were numerically less frequent in group 1 than group 2, although this difference was not assessed statistically. In both groups, all participants included in the immunogenicity analysis achieved anti-Hep B ≥ 10 mIU/mL and ≥ 96.2% of participants achieved anti-Hep B ≥ 100 mIU/mL, although geometric mean titer was approximately 3-fold lower for the investigational vaccine.

CONCLUSION

This new, fully liquid acellular pertussis hexavalent vaccine demonstrated less reactogenicity than the licensed comparator whole cell pertussis vaccine and was highly immunogenic for the new Hep B valence.

Risk of convulsions in children after monovalent H1N1 (2009) and trivalent influenza vaccines: a database study

The monovalent H1N1 (2009) pandemic influenza vaccine used predominantly in the UK in 2009/10 was a split virion vaccine with a novel oil-in-water adjuvant (ASO3). While this was highly immunogenic it was also reactogenic especially for fever in children. There is a paucity of comparative data on reactogenicity of trivalent influenza vaccine (TIV). Using the General Practice Research Database (GPRD) we investigated whether there was an increased risk of convulsions in children vaccinated with monovalent H1N1 influenza vaccine in the 2009/10 season and also the risk after vaccination with the seasonal TIVs using the self-controlled case-series method. A total of 2366 children aged under 10 years with at least one convulsion recorded in the GPRD and who had received at least one influenza vaccine at anytime (2858 doses of TIV and 1895 doses of the monovalent H1N1 influenza vaccine) were identified between May 2000 and April 2010. Over this period these 2366 children had a total of 3846 convulsion episodes. There was no increase in the incidence rate ratio (IRR) in the week after vaccination for either the monovalent H1N1 influenza vaccine (IRR 0.99, 95% CI 0.61-1.60) or the first dose of TIV (IRR 0.89, 95% CI 0.53-1.52). A signal of an elevated risk in the first few days after the second dose of monovalent H1N1 influenza vaccine was seen with an IRR for days 1-3 post vaccination of 3.48 (95% CI 0.86-14.07). This is consistent with findings of increased fever in a clinical trial. These results neither provide evidence of an increased risk of convulsions following TIV over a 10-year surveillance period nor following a single dose of the ASO3 adjuvanted monovalent H1N1 vaccine in 2009/10.

Update on available vaccines in India: report of the APPA VU 2010: I

The Asia Pacific Pediatric Association Vaccinology Update 2010 was held in Mumbai on November 13-14, 2010 to discuss the latest information on burden of infectious diseases, recent developments in vaccines and their impact on immunization practices against infectious diseases occurring in Indian children. During the conference the importance of including conjugate Haemophilus influenzae type b vaccine and anti-rabies vaccines in routine immunization was stressed. Also, the need for giving a second dose of measles mumps rubella vaccine at school entry; and the need for a two-dose varicella vaccine regimen (first dose at 12-15 months of age and a second dose at age 4-6 years) was elucidated. Information related to vaccines which have become available in India in recent years, namely, inactivated poliovirus vaccine; diphtheria, tetanus, acellular pertussis (DTaP) vaccine; conjugate pneumococcal vaccine; rotavirus vaccines; H1N1 vaccines; live attenuated hepatitis A virus vaccine; oral cholera vaccine; tetanus, reduced-dose diphtheria, acellular pertussis (Tdap) vaccine; and human papillomavirus vaccines were discussed.

Post-licensure comparison of the safety profile of diphtheria/tetanus/whole cell pertussis/haemophilus influenza type b vaccine and a 5-in-1 diphtheria/tetanus/acellular pertussis/haemophilus influenza type b/polio vaccine in the United Kingdom

General practitioner consultation data were used to compare the reactogenicity in infants of a 5-in-1 acellular pertussis vaccine (DTaP(5)/Hib/IPV) introduced in the United Kingdom in 2004 to the 4-in-1 whole cell-pertussis vaccine (DTwP/Hib) that it replaced. For each vaccine the incidence in the week following vaccination was compared to other periods to obtain a relative incidence. A lower relative incidence of crying, fever and local reactions was seen with DTaP(5)/Hib/IPV than DTwP/Hib. Although there were no other significant differences between vaccines the relative incidence was significantly above one on the day of vaccination for convulsions following DTwP/Hib and for apnoea/collapse following DTaP(5)/Hib/IPV.

Epidemiology of pertussis and Haemophilus influenzae type b disease in Canada with exclusive use of a diphtheria-tetanus-acellular pertussis-inactivated poliovirus-Haemophilus influenzae type b pediatric combination vaccine and an adolescent-adult tetanus-diphtheria-acellular pertussis vaccine: implications for disease prevention in the United States

BACKGROUND

During the decade 1998-2007, a combination DTaP(5)-IPV/Hib vaccine was used exclusively in Canada to immunize infants and young children against diphtheria, tetanus, pertussis, polio, and invasive Haemophilus influenzae type b (Hib) disease.

METHODS

Medline was used to search for publications during 1996-2008 related to the epidemiology and vaccine prevention of pertussis and invasive Hib disease in Canada. Related abstracts and presentations were reviewed, when available, and epidemiologic data since 1985 were obtained from the Public Health Agency of Canada public Web site.

RESULTS

Reports of pertussis have declined substantially in preschool and school-aged children during the past decade, and cyclical peaks in disease incidence have been blunted or eliminated. In provinces and territories where Tdap(5) vaccine has been administered to 14- to 16-year-olds, marked reductions of pertussis have been documented in adolescents as well as younger age groups, possibly due to herd immunity. Incidence rates of invasive Hib disease among Canadian children <5 years declined markedly after introduction of Hib conjugate vaccines, and the disease has remained under control with exclusive use of DTaP(5)-IPV/Hib vaccine. Most cases of invasive Hib disease occur among unimmunized or only partially vaccinated children. The reduction of Hib case reports has been documented throughout Canada, including among Aboriginal children who are at high risk for this disease.

CONCLUSIONS

The Canadian experience with DTaP(5)-IPV/Hib and Tdap(5) vaccines is relevant to the United States because immunization schedules, vaccination coverage rates, and epidemiologic patterns of pertussis and Hib diseases are similar in the 2 countries, and because both vaccines are licensed for use in the United States.

Comparison of acellular pertussis-based combination vaccines by Japanese control tests for toxicities and laboratory models for local reaction

Two batches each of diphtheria -- tetanus -- acellular pertussis vaccine (DTaP) and that combined with inactivated polio vaccine purchased from the U.S.A., European and Asian markets were compared with Japanese DTaPs by Japanese control tests for DTaP and laboratory models for local reaction. All the imported vaccines met Japanese criteria for toxicities of acellular pertussis vaccine except for the toxicity to mouse weight gain (body weight decreasing (BWD) toxicity). When injecting into mouse footpad, rabbit back skin and mouse quadriceps muscle, the imported vaccines induced much severer inflammation and tissue injury comparing to Japanese DTaPs irrespective of animal species, injection site and injection volume suggesting that these vaccines may induce stronger local reactogenicity.

DTPa-HBV-IPV vaccine for primary vaccination of infants

AIM

Combined vaccines have an increasingly important role to play in delivering these antigens acceptably. We describe the immunogenicity and reactogenicity of a combined DTPa-HBV-IPV vaccine (diphtheria, tetanus, acellular pertussis, hepatitis B, inactivated poliovirus (DTPa-HBV-IPV: Infanrix penta) ) when administered for the primary vaccination of infants resulting from a study where the primary objective was to demonstrate non-inferiority of the immune response induced by DTPa-HBV-IPV using an industrial-scale IPV production process.

METHODS

Three hundred and fourteen infants received primary immunisation with DTPa-HBV-IPV at 2, 4 and 6 months of age. Routine Haemophilus influenzae immunisation was performed at 2 and 4 months of age at a separate injection site. Blood samples were taken at 2 and 7 months of age. Reactogenicity was assessed using diary cards for 7 days after each dose.

RESULTS

One month after the primary course, at least 98.9% of subjects achieved seroprotective antibody concentrations/titres against diphtheria, tetanus, hepatitis-B and polio types 1, 2 and 3. More than 97% had a vaccine response to pertussis antigens. The incidence of local injection site reactions after DTPa-HBV-IPV was similar to that for the Haemophilus influenzae vaccine site. General reactions of Grade 3 intensity were uncommon.

CONCLUSIONS

The DTPa-HBV-IPV vaccine is a new combination of vaccines previously available separately, with established effectiveness and safety profiles. Combined vaccines reduce storage requirements and minimise the number of injections required, thereby reducing distress for infants and parents. DTPa-HBV-IPV was immunogenic with an acceptable safety profile and could replace separate administration of DTPa, HBV and IPV vaccines in infants.

Safety and immunogenicity of a fully liquid vaccine containing five-component pertussis-diphtheria-tetanus-inactivated poliomyelitis-Haemophilus influenzae type b conjugate vaccines administered at two, four, six and 18 months of age

OBJECTIVE

The safety, immunogenicity and lot consistency of a fully liquid, five-component acellular pertussis combination vaccine, comprised of diphteria, tetanus and acellular pertussis, inactivated polio vaccine, Haemophilus influenzae type b (DTaP-IPV-Hib [Pediacel, sanofi pasteur, Canada]) were assessed and compared with that of Hib vaccine reconstituted with the five-component acellular pertussis combination vaccine (DTaP-IPV//Hib, Pentacel [sanofi pasteur, Canada]).

METHODS

Infants were recruited at vaccine study centres in Montreal, Quebec; Simon Fraser Health Region, British Columbia, and southern Alberta after the protocol had been approved by the relevant institutional ethics committees. Written informed consent was obtained from the parents or guardians of all subjects. At two months of age, the infants were randomly assigned to receive one of three consecutive production lots of DTaP-IPV-Hib by intramuscular injection. Reactions to vaccinations were assessed by parental observation and through telephone interviews conducted by study nurses. Blood samples were obtained at two, six, seven, 18 and 19 months of age for measurement of antibodies to vaccine antigens.

RESULTS

Most injection site and systemic reactions were mild or moderate, and of brief duration. All infants were protected against tetanus, diphtheria and all three polio serotypes after both primary and booster vaccinations. Antibody responses to pertussis antigens were similar to those observed in Swedish infants, in whom the five-component vaccine was shown to be 85% effective. Proportions of infants with antipolyribosylribitol phosphate antibody of 0.15 mug/mL or greater and 1.0 mug/mL or greater, were 97.9% and 88.9%, respectively, following primary immunization, and 100% and 99% following booster vaccination. Safety and immunogenicity results with both reconstituted and fully liquid combination vaccines were comparable.

CONCLUSIONS

The fully liquid combination vaccine was comparable in terms of safety and immunogenicity with the reconstituted combination vaccine.

Vaccination, seizures and ‘vaccine damage’

PURPOSE OF REVIEW

Concerns about the safety of vaccination have plagued the community, with reduction in vaccine uptake resulting in increased risk of epidemics. Vaccination has been implicated in the cause of febrile seizures, 'vaccine encephalopathy' and autistic spectrum disorders. Evaluation of alleged associations is complicated by evolution in the vaccination field. This review focuses on the risk of seizures following vaccination and the alleged associations of vaccination with vaccine encephalopathy and also with autism spectrum disorders.

RECENT FINDINGS

Over the last decade the introduction of new vaccines such as the acellular pertussis vaccine has produced a reduction in seizures following vaccination, the outcome of which was benign even with older vaccines. New evidence emerged in 2006 showing that cases of alleged 'vaccine encephalopathy' are due to mutations within a sodium channel gene. The weight of epidemiological evidence does not support a relationship between vaccination and childhood epileptic encephalopathies or autism spectrum disorders.

SUMMARY

Vaccines are safer than ever before, but the challenge remains to convey this message to society in such a way that produces change in attitudes to vaccination and subsequent increase in vaccine coverage.

One-year post-primary antibody persistence and booster immune response to a fully liquid five-component acellular pertussis, diphtheria, tetanus, inactivated poliomyelitis, Haemophilus influenzae type b conjugate vaccine

OBJECTIVE

To evaluate antibody persistence one year after three-dose primary vaccination and booster immune response during the second year of life for a fully liquid diphtheria-tetanus-acellular pertussis-inactivated poliomyelitis-Haemophilus influenzae type b (DTaP-IPV-PRP approximately T) vaccine.

METHODS

Infants at 18-19 months of age were given a booster dose of either DTaP-IPV-PRP approximately T (group A) or DTaP-IPV plus PRP approximately T at separate injection sites (group B), after primary vaccination at two, four and six months of age, with the same vaccines. Antibody concentrations were measured pre- and post-booster. Reactogenicity and safety were evaluated from parent reports.

RESULTS

Before the booster dose, 93.1% of group A and 95.1% of group B children still had anti-PRP antibody titers > or =0.15 microg/ml. All children had antibody levels believed to protect against tetanus, polio 1 (except one subject in group B), polio 2, polio 3, and diphtheria (except one subject in group A). At least 94% of children still had antibody concentrations > or =5 ELISA units (EU) to pertussis antigens (pertussis toxoid (PT), filamentous hemagglutinin (FHA), pertactin (PRN), fimbriae 2 and 3 (FIM2+3)). One month after the booster dose, all subjects achieved antibody concentrations or titers believed to be protective for PRP (polyribose ribitol phosphate)(> or =1 microg/ml), diphtheria and tetanus (> or =0.1 IU/ml) and poliovirus types 1, 2, and 3 (> or =81/dil.), and at least 90.5% of subjects had four-fold increases in antibody concentrations to pertussis antigens following the booster. Anti-PRP geometric mean titers (GMTs) increased from 1.07 to 59.6 microg/ml and from 1.8 to 62.2 microg/ml in groups A and B, respectively. Both vaccine groups showed low reactogenicity rates.

CONCLUSIONS

The fully liquid pentavalent DTaP-IPV-PRP approximately T vaccine is highly immunogenic, with good antibody persistence for each antigen approximately one year after primary vaccination and strong booster responses at 18-19 months of age. Because this combined vaccine is fully liquid, requiring no reconstitution of lyophilized PRP approximately T, the ease of use and proper administration are improved.

New combination vaccines still need a boost

Perspective on the paper by Kitchin et al (see page XXX)

Prevention of pertussis across the age spectrum through the use of the combination vaccines PENTACEL™ and ADACEL™

Acellular pertussis-containing combination vaccines are widely used in the developed world for the control of pertussis and have been successful in controlling disease in preschool-aged children. Combination vaccines formulated for use in adolescents and adults have been developed more recently and are increasingly being implemented for the control of pertussis in these age groups. One such family of products is PENTACEL (Haemophilus influenzae type b conjugate vaccine reconstituted with component pertussis vaccine and diphtheria and tetanus toxoids adsorbed combined with inactivated poliomyelitis vaccine, DTaP-IPV-Hib), for use in young children, and ADACEL (tetanus and diphtheria toxoids adsorbed combined with component pertussis vaccine, dTap) for use in adolescents and adults. These products have been demonstrated to be safe, immunogenic and effective for the control of pertussis and the other included diseases.

Vaccination-related adverse events

Vaccine-related adverse events are uncommon and typically mild. Children may experience conditions such as rashes, fevers, syncope, protracted crying, or seizures shortly after receiving their routine immunizations. When children are brought to the emergency department or clinic to be evaluated for one of these conditions, the health care provider may be called upon to determine the likelihood that it was caused by a recently administered set of vaccines. This determination has substantial implications for medical care, including the safety of administering future vaccines. This article reviews the current understanding of vaccine-related adverse events. Using this information, clinicians should be able to identify those events likely to be related to vaccine administration and those that are not. The appropriate management of vaccine-related adverse events is also discussed.

Febrile seizure: measuring adherence to AAP guidelines among community ED physicians

OBJECTIVE

In 1996, the American Academy of Pediatrics published practice parameters for the acute management of febrile seizure. These guidelines emphasize the typically benign nature of the condition and discourage aggressive neurodiagnostic evaluation. The extent to which these suggestions have been adopted by general emergency medicine practitioners is unknown. We sought to describe recent patterns of the emergency department (ED) evaluation of febrile seizures with respect to these parameters.

METHODS

A retrospective review of records of children between 6 month and 6 years of age diagnosed with "febrile seizure" (International Classification of Diseases, Ninth Revision, Clinical Modification 780.31) at 42 community hospital general EDs nationwide was performed. Electronic records of an ED physician billing service from October 2002 to September 2003 were used to identify relevant records. Data had been entered into a proprietary template documentation system, and all charts were reviewed by a professional coder blinded to outcomes of interest. Rates of resource utilization (including lumbar puncture, radiography, hospital admission) were noted.

RESULTS

A total of 1029 charts met inclusion criteria. The overall rate of lumbar puncture was 5.2%, and variations were strongly associated with age (8.4% <18 months old vs 3.3% >18 months old). This low rate and age discrimination were consistent with the guidelines of the American Academy of Pediatrics. Although not recommended in the routine evaluation of febrile seizure, computed tomography was part of the evaluation in 11%. The overall rate of admissions or transfers was 12%.

CONCLUSIONS

Six years after publication of practice parameters, the use of lumbar puncture in the evaluation of febrile seizure is uncommon and most patients are discharged home. However, the relatively frequent use of head computed tomography is inconsistent with these practice guidelines and merits further investigation.

A fully liquid diphtheria-tetanus-five component acellular pertussis-inactivated poliomyelitis--Haemophilus influenzae type b conjugate vaccine: immunogenicity and safety of primary vaccination in Taiwanese infants

OBJECTIVE

To assess the immunogenicity of a fully liquid diphtheria-tetanus-five component acellular pertussis-inactivated poliomyelitis-Haemophilus influenzae type b (DTaP-IPV-Hib) conjugate vaccine compared to DTaP-IPV and lyophilized Hib conjugate vaccines given simultaneously at separate sites as a three-dose primary vaccination in Taiwanese infants.

METHODS

Two hundred infants were randomized to receive either DTaP-IPV-Hib or DTaP-IPV plus Hib vaccine at 2, 4, and 6 months of age. Both combined vaccines contained the same five pertussis antigens: pertussis toxoid (PT), filamentous hemagglutinin (FHA), pertactin (PRN), fimbriae 2 and 3 (FIM 2&3). Antibody concentrations were measured before the first and after the third dose. Reactogenicity was evaluated from parental reports. All subjects received hepatitis B vaccine at 0, 1, and 6 months of age following the national vaccination schedule of Taiwan.

RESULTS

The immunogenicity after the third dose was high for each vaccine antigen in both groups, and the vaccines had low reactogenicity. Statistical analysis showed no differences in the immune responses to the fully liquid DTaP-IPV-Hib vaccine compared with those to the DTaP-IPV plus Hib control vaccines, notably the anti-PRP (polyribose ribitol phosphate capsular polysaccharide) response, with 97-99% of infants having concentrations >or=1.0 microg/mL. Approximately 95% of all infants developed seroprotective levels of anti-hepatitis B surface antigen (HBs) antibodies (>or=10 mIU/mL).

CONCLUSIONS

Both combination vaccines had similar high immunogenicity for each antigen, and both were well tolerated. Thus, inclusion of a Haemophilus influenzae type b conjugate vaccine in the combination did not result in clinically significant decrease in the PRP response or increase reactogenicity. The fully liquid pentavalent vaccine has the advantages of not requiring reconstitution and of administration as a single injection.