Postvaccination Febrile Seizure Severity and Outcome

Febrile Seizures

Febrile seizures (FSs) are the most common cause of pediatric seizures. They are defined as seizures in children age 6 months to 5 years with a temperature higher than 100.4°F, although they are more common at higher temperatures. A family history of FS is the most common risk factor. FSs are classified into three types (simple, complex, or febrile status epilepticus) based on duration and quality, with simple FSs accounting for many cases. Most FSs persist for less than 10 minutes and are self-limiting. Approximately one-third of patients will have recurrence of FSs. Safe and effective prophylaxis for FS has yet to be identified. Most patients will not have any long-term sequelae, although there is an increased risk of epilepsy, particularly for those with febrile status epilepticus. FSs are associated with caregiver anxiety, "fever phobia," and high health care use, emphasizing the importance of education and reassurance for both the provider and family. [Pediatr Ann. 2023;52(10):e388-e393.].

The baseline risk of multiple febrile seizures in the same febrile illness: a meta-analysis

The baseline risk for multiple febrile seizures within the same febrile illness is largely unknown. Estimates range from 5 to 30%. Imprecise estimates can lead to incorrectly powering studies investigating the management of febrile seizures. To estimate the risk of multiple febrile seizures in the same febrile illness, we systematically reviewed and conducted a meta-analysis of studies from January 2000 to December 2021 that contained data for the number of children for both simple and complex febrile seizures in the same febrile illness. We searched MEDLINE, EMBASE, and Web of Science for randomized, quasi-randomized, prospective, and retrospective trials that involved children with febrile seizures. A total of 23,131 febrile illnesses with febrile seizures met the inclusion criteria. The estimated baseline risk of multiple febrile seizures in the same febrile illness was 17% (95% CI, 16-19%). However, the 30 cohorts that included both admitted and non-admitted patients had a lower percentage of multiple FSs within the same illness (14%; 95% CI, 12-15%) than the 30 cohorts that enrolled only admitted patients (20%; 95% CI, 16-25%).

CONCLUSION

Researchers can use estimates in this paper to design future studies. Taking into the account the substantial heterogeneity between countries and studies, clinicians could cautiously use our estimates in their clinical assessment and be better able to set parental expectations about a child's chances of having another febrile seizure during the current illness.

TRIAL REGISTRATION

PROSPERO CRD42020191784. Registered July 18, 2020.

WHAT IS KNOWN

• There is renewed interest in the diagnostic workup and prophylactic treatment of febrile seizures to prevent repeat seizures in the same febrile illness. • There is a lack of accurate estimates of the baseline risk for multiple febrile seizures in the same illness to properly design studies investigating management.

WHAT IS NEW

• This study provides the most robust estimates for the baseline risk for multiple febrile seizures in the same illness.

Status epilepticus following vaccination in children aged ≤24 months: A five-year retrospective observational study

BACKGROUND

Status epilepticus is associated with significant morbidity and mortality. While vaccine-proximate status epilepticus (VP-SE) has rarely been associated with cases of Dravet syndrome, it is not known whether VP-SE differs clinically from non-vaccine proximate status epilepticus (NVP-SE).

METHODS

Medical records of children aged ≤24 months, presenting to one of five Australian tertiary pediatric hospitals with their first episode of status epilepticus from 2013 to 2017 were identified using ICD-coded discharge diagnoses. Vaccination history was obtained from the Australian Immunisation Register. Hospitalization details, subsequent epilepsy diagnosis, and vaccination uptake were compared between VP-SE and NVP-SE cases.

RESULTS

Of 245 first status epilepticus hospitalization with immunization records, 35 (14%) were VP-SE and 21 (60%) followed measles-containing vaccines. Vaccine-proximate status epilepticus cases had a median age of 12.5 months [IQR 7.1-14.73], 23 (66%) were in males, 15 (43%) were febrile status epilepticus and 17 (49%) had an infection confirmed. There were no significant differences in hospitalization duration (P = 0.50) or intensive care unit admission (P = 0.42) between children with VP-SE compared to children with NVP-SE. Children with no history of seizures at their first VP-SE had longer hospitalizations, were more likely to require intensive care unit admission, but were less likely to have a subsequent diagnosis of epilepsy than children with previous seizures at their first VP-SE.

CONCLUSION

First VP-SE was predominantly associated with a measles-containing vaccine at 12-months of age. Seizure severity was no different between first VP-SE and first NVP-SE. In children with VP-SE, subsequent seizure admissions and epilepsy diagnosis were associated with having seizure prior to their first SE.

Status epilepticus outcomes among vaccinated and unvaccinated children: A population-based study

AIM

To determine the proportion of first status epilepticus (SE) cases that are vaccine-proximate (VP-) and compare clinical outcomes to non-vaccine-proximate (NVP-) cases.

METHODS

Birth records for 1,440,807 Australian children born in 1998-2012, were probabilistically linked to hospitalizations, deaths, and vaccination history available to 2013. First SE coded hospitalizations were categorized as VP-SE or NVP-SE; clinical severity and post-SE vaccination coverage were compared. SE rates were calculated.

RESULTS

Of 867 first SE cases (7.9 per 100,000 person-years), 31 (3.6%) were VP-SE; 16 followed dose-1 measles vaccine (1.2 SE per 100,000 doses). Compared with NVP-SE, VP-SE cases were younger (1.0 vs 2.6 years, P < 0.0001) and had longer hospitalizations (4 vs 3 days, P = 0.005). There was no difference in the proportion of VP-SE cases with a coinfection diagnosis compared to NVP-SE (25.8% vs 19.9%, P = 0.42). Controlling for age and history of hospitalization for a neurological condition, intensive care unit (ICU) admission had a stronger association with coinfection (aOR 2.52 (95%CI 1.78-3.57)) than having VP-SE (aOR 1.41 (0.66-3.01)). Groups had similar SE recurrence rates at 12-months (12.9% VP vs 16.9% NVP, P = 0.56) and reduced vaccine uptake following initial SE (from 93.5% to 56.3%).

CONCLUSION

Proportionally few first SE cases were VP-SE, with higher ICU admission rates mostly explained by younger age and higher coinfection rates. Vaccination plans are needed to improve vaccine uptake following SE.

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.

From program suspension to the pandemic: A qualitative examination of Australia's vaccine pharmacovigilance system over 10 years

BACKGROUND

In 2010, the Australian seasonal influenza vaccination program for children under 5 years of age was suspended due to an unexpected increase in fever and febrile convulsions causally associated with one particular influenza vaccine brand. A subsequent national review made seven recommendations to improve vaccine pharmacovigilance. Ten years on, in advance of implementing the COVID-19 immunisation program, we evaluated views on the capacity of Australia's vaccine pharmacovigilance system to promptly detect, examine and communicate a signal.

METHODS

Semi-structured interviews were conducted between July and October 2020 with individuals with expertise in vaccine safety in Australia using an interview guide informed by key Australian and international frameworks. Interviews were digitally recorded and transcribed verbatim. Thematic analysis was used to code data using a deductive approach.

RESULTS

Interviews with seventeen participants enabled six themes to be identified. Participants described improvement and significant innovation within Australia's vaccine pharmacovigilance system over the decade since 2010, particularly through establishment of a new active, cohort event monitoring system using short message service surveys. Participants thought Australia had a good foundation for COVID-19 vaccine safety surveillance; implementation of the COVID-19 immunisation program was seen as a potential driver for ongoing enhancement through: a) improved integration of the active surveillance and spontaneous reporting systems, and; b) development of population-level active surveillance, including through data linkage. Transparent communication was considered essential to address the unprecedented challenges of COVID-19 and broader vaccine safety concerns.

CONCLUSIONS

Vaccine safety experts in Australia convey confidence in the innovative pharmacovigilance systems implemented over the past 10 years. While Australia has a multifaceted system incorporating both active surveillance and spontaneous reporting systems, COVID-19 vaccine implementation represents an opportunity to enhance current systems and to develop new, systematic approaches to vaccine pharmacovigilance that should make both a local and global contribution.

Study of Febrile Seizure among Hospitalized Children of a Tertiary Centre of Nepal: A Descriptive Cross-sectional Study

INTRODUCTION

Febrile seizure is the commonest cause of seizure in children and appears mostly between 6-60 months of life. The objective of this study is to find out the prevalence of febrile seizure among hospitalized children of a tertiary centre of Nepal.

METHODS

This is a descriptive cross-sectional study conducted in a teaching hospital of central Nepal, from 2014 January to 2019 December. After obtaining ethical clearance from Institutional Review Committee (Reference number: 2019-038), clinical and demographic data was retrieved from patient record retrospectively and reviewed for completeness and accuracy; those fulfilling the definition of febrile seizure were enrolled in the study. Convenience sampling technique was used. The data was analyzed using Statistical Packages for Social Sciences Version 25. Point estimate is done at 95% Confidence Interval and frequency and proportion was calculated.

RESULTS

Out of 4890 cases admitted during the study period, 214 (4.37%) (3.80%-4.94% at 95% Confidence Interval) children were diagnosed with febrile seizure. One hundred thirty one (62%) children had a simple febrile seizure. In majority of the cases, seizure lasted for less than 5 minutes; however, 10 (4.6%) of them presented with febrile status epilepticus, 111 (52%) children had generalised tonic seizure and upper respiratory tract infection was the commonest cause of fever.

CONCLUSIONS

Prevalence of febrile seizure is significant among hospitalized children and simple febrile seizure is the commonest type. A substantial number of children present in febrile status epilepticus, even though the duration of febrile seizure is brief in most of the cases.

Active Vaccine Safety Surveillance: Global Trends and Challenges in China

Importance. The great success in vaccine-preventable diseases has been accompanied by vaccine safety concerns. This has caused vaccine hesitancy to be the top 10 in threats to global health. The comprehensive understanding of adverse events following immunization should be entirely based on clinical trials and postapproval surveillance. It has increasingly been recognized worldwide that the active surveillance of vaccine safety should be an essential part of immunization programs due to its complementary advantages to passive surveillance and clinical trials.Highlights. In the present study, the framework of vaccine safety surveillance was summarized to illustrate the importance of active surveillance and address vaccine hesitancy or safety concerns. Then, the global progress of active surveillance systems was reviewed, mainly focusing on population-based or hospital-based active surveillance. With these successful paradigms, the practical and reliable ways to create robust and similar systems in China were discussed and presented from the perspective of available databases, methodology challenges, policy supports, and ethical considerations.Conclusion. In the inevitable trend of the global vaccine safety ecosystem, the establishment of an active surveillance system for vaccine safety in China is urgent and feasible. This process can be accelerated with the consensus and cooperation of regulatory departments, research institutions, and data owners.

Revaccination outcomes of children with vaccine proximate seizures

BACKGROUND

Seizures, whether febrile or afebrile, occurring within 14 days following vaccination can be considered as vaccine proximate seizures (VPSs). While the attributable risk and clinical severity of first febrile VPS is well known, the risk and clinical outcomes of VPS recurrence is less well defined.

METHODS

We conducted a retrospective review of revaccination management and outcomes in children who experienced a VPS as their first seizure seen in Australian Specialist Immunisation Clinics between 2013 and 2017. Vaccination outcomes were compared between children who had a VPS as their only seizure (VPS only) and children who had further non-vaccine proximate seizures following their initial VPS (VPS+) prior to review at the clinic.

RESULTS

We identified 119 children with a VPS as their first seizure, of which 61 (51%) went on to have other seizures (VPS+). Children with VPS+ were more likely to present at a younger age (6.2 vs 12.5 months, P = 0.03), with afebrile seizures (42.6% vs 15.5%, P = 0.002) compared to VPS only children. VPS recurrence on revaccination was uncommon in both groups, but more common in VPS+ children (12.5% vs 2.4%, P = 0.07). Having an epilepsy diagnosis, specifically Dravet syndrome, was associated with VPS recurrence (P < 0.001). Of the four children with Dravet syndrome who had VPS recurrence, all had status epilepticus following revaccination.

CONCLUSION

In children who presented with a single VPS as their only seizure, VPS recurrence on revaccination was uncommon. Children who had multiple non-vaccine proximate seizures following their initial VPS (VPS+) were more likely to present with afebrile VPS, at a younger age and have a VPS recurrence with vaccination. In these children, particularly those aged < 12 months, assessment and investigation for diagnosis of Dravet syndrome should be considered and additional precautions for revaccination undertaken as they are at highest risk of VPS recurrence.

Establishing and Maintaining a Vaccine-Positive Practice Culture

A vaccine-positive practice culture encourages immunization against vaccine-preventable diseases by supporting policies and practices that reduce barriers and improve efficacy for vaccine delivery. Key components of a vaccine-positive practice include a well-trained, knowledgeable, collaborative health care practice team; access to immunizations in the practice; and a vaccine practice champion. Leveraging these encourages a provaccine environment and fosters productive dialogue, even among vaccine-hesitant patients/parents.

Developmental outcomes following vaccine-proximate febrile seizures in children

OBJECTIVE

To compare the developmental and behavioral outcomes of children experiencing an initial vaccine-proximate (VP) febrile seizure (FS) to those having a non-VP-FS (NVP-FS) and controls who have not had a seizure.

METHODS

In this prospective multicenter cohort study, children with their first FS before 30 months of age between May 2013 and April 2016 were recruited from 4 Australian pediatric hospitals and classified as having VP-FS or NVP-FS. Similar-aged children with no seizure history were recruited as controls. The Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III) was administered to participants with FS 12 to 24 months after their initial FS and to controls 12 to 42 months of age at the time of assessment. The primary outcome was the Bayley-III cognitive score. Children's preacademic skills were assessed with the Woodcock-Johnson Tests of Achievement, Third Edition, and their behavior and executive functioning were obtained from parent questionnaires.

RESULTS

There was no significant difference in cognitive function between children with VP-FS (n = 62), those with NVP-FS (n = 70), and controls (n = 90) (F _2,219 = 2.645, p = 0.07). There were no differences between the groups for all other measures and no increased risk of borderline/significant impairment or behavior in the clinical range in children with VP-FS compared to those with NVP-FS or controls.

CONCLUSION

VP-FS was not associated with an increased risk of developmental or behavioral problems in young children compared to children with NVP-FS or controls. Parents and providers should be reassured by the absence of adverse effects of VP-FS on the development of children.

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.

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.