Increased incidence and clinical picture of childhood narcolepsy following the 2009 H1N1 pandemic vaccination campaign in Finland

Properties and prospects of adjuvants in influenza vaccination - messy precipitates or blessed opportunities?

Influenza is a major challenge to healthcare systems world-wide. While prophylactic vaccination is largely efficient, long-lasting immunity has not been achieved in immunized populations, at least in part due to the challenges arising from the antigen variation between strains of influenza A virus as a consequence of genetic drift and shift. From progress in our understanding of the immune system, the mode-of-action of vaccines can be divided into the stimulation of the adaptive system through inclusion of appropriate vaccine antigens and of the innate immune system by the addition of adjuvant to the vaccine formulation. A shared property of many vaccine adjuvants is found in their nature of water-insoluble precipitates, for instance the particulate material made from aluminum salts. Previously, it was thought that embedding of vaccine antigens in these materials provided a "depot" of antigens enabling a long exposure of the immune system to the antigen. However, more recent work points to a role of particulate adjuvants in stimulating cellular parts of the innate immune system. Here, we briefly outline the infectious medicine and immune biology of influenza virus infection and procedures to provide sufficient and stably available amounts of vaccine antigen. This is followed by presentation of the many roles of adjuvants, which involve humoral factors of innate immunity, notably complement. In a perspective of the ultrastructural properties of these humoral factors, it becomes possible to rationalize why these insoluble precipitates or emulsions are such a provocation of the immune system. We propose that the biophysics of particulate material may hold opportunities that could aid the development of more efficient influenza vaccines.

Genome wide analysis of narcolepsy in China implicates novel immune loci and reveals changes in association prior to versus after the 2009 H1N1 influenza pandemic

Previous studies in narcolepsy, an autoimmune disorder affecting hypocretin (orexin) neurons and recently associated with H1N1 influenza, have demonstrated significant associations with five loci. Using a well-characterized Chinese cohort, we refined known associations in TRA@ and P2RY11-DNMT1 and identified new associations in the TCR beta (TRB@; rs9648789 max P = 3.7×10⁻⁹ OR 0.77), ZNF365 (rs10995245 max P = 1.2×10⁻¹¹ OR 1.23), and IL10RB-IFNAR1 loci (rs2252931 max P = 2.2×10⁻⁹ OR 0.75). Variants in the Human Leukocyte Antigen (HLA)- DQ region were associated with age of onset (rs7744020 P = 7.9×10⁻⁹ beta −1.9 years) and varied significantly among cases with onset after the 2009 H1N1 influenza pandemic compared to previous years (rs9271117 P = 7.8×10⁻¹⁰ OR 0.57). These reflected an association of DQB1*03:01 with earlier onset and decreased DQB1*06:02 homozygosity following 2009. Our results illustrate how genetic association can change in the presence of new environmental challenges and suggest that the monitoring of genetic architecture over time may help reveal the appearance of novel triggers for autoimmune diseases.

Narcolepsy-hypocretin deficiency results from a highly specific autoimmune attack on hypocretin cells. Recent studies have established antigen presentation by specific class II proteins encoded by (HLA DQB1*06:02 and DQA1*01:02) to the cognate T cell receptor as the main disease pathway, with a role for H1N1 influenza in the triggering process. Here, we have used a large and well-characterized cohort of Chinese narcolepsy cases to examine genetic architecture not observed in European samples. We confirmed previously implicated susceptibility genes (T cell receptor alpha, P2RY11), and identify new loci (ZNF365, IL10RB-IFNAR1), most notably, variants at the beta chain of the T cell receptor. We found that one HLA variant, (DQB1*03:01), is associated with dramatically earlier disease onset (nearly 2 years). We also identified differences in HLA haplotype frequencies among cases with onset following the 2009 H1N1 influenza pandemic as compared to before the outbreak, with fewer HLA DQB1*06:02 homozygotes. This may be the first demonstration of such an effect, and suggests that the study of changes in GWAS signals over time could help identify environmental factors in other autoimmune diseases.

Increased risk of narcolepsy in children and adults after pandemic H1N1 vaccination in France

An increased incidence of narcolepsy in children was detected in Scandinavian countries where pandemic H1N1 influenza ASO3-adjuvanted vaccine was used. A campaign of vaccination against pandemic H1N1 influenza was implemented in France using both ASO3-adjuvanted and non-adjuvanted vaccines. As part of a study considering all-type narcolepsy, we investigated the association between H1N1 vaccination and narcolepsy with cataplexy in children and adults compared with matched controls; and compared the phenotype of narcolepsy with cataplexy according to exposure to the H1N1 vaccination. Patients with narcolepsy-cataplexy were included from 14 expert centres in France. Date of diagnosis constituted the index date. Validation of cases was performed by independent experts using the Brighton collaboration criteria. Up to four controls were individually matched to cases according to age, gender and geographic location. A structured telephone interview was performed to collect information on medical history, past infections and vaccinations. Eighty-five cases with narcolepsy-cataplexy were included; 23 being further excluded regarding eligibility criteria. Of the 62 eligible cases, 59 (64% males, 57.6% children) could be matched with 135 control subjects. H1N1 vaccination was associated with narcolepsy-cataplexy with an odds ratio of 6.5 (2.1-19.9) in subjects aged<18 years, and 4.7 (1.6-13.9) in those aged 18 and over. Sensitivity analyses considering date of referral for diagnosis or the date of onset of symptoms as the index date gave similar results, as did analyses focusing only on exposure to ASO3-adjuvanted vaccine. Slight differences were found when comparing cases with narcolepsy-cataplexy exposed to H1N1 vaccination (n=32; mostly AS03-adjuvanted vaccine, n=28) to non-exposed cases (n=30), including shorter delay of diagnosis and a higher number of sleep onset rapid eye movement periods for exposed cases. No difference was found regarding history of infections. In this sub-analysis, H1N1 vaccination was strongly associated with an increased risk of narcolepsy-cataplexy in both children and adults in France. Even if, as in every observational study, the possibility that some biases participated in the association cannot be completely ruled out, the associations appeared robust to sensitivity analyses, and a specific analysis focusing on ASO3-adjuvanted vaccine found similar increase.

Increased plasma level of tumor necrosis factor α in patients with narcolepsy in Taiwan

BACKGROUND

Narcolepsy is a neuropsychiatric disorder characterized by excessive daytime sleepiness, cataplexy, hypnagogic hallucinations, and abnormal rapid eye movement (REM) sleep. Tumor necrosis factor α (TNF α) and its cognate receptors have been reported to be involved in the pathophysiology of narcolepsy in addition to the HLA antigen system. Our study aimed to determine if the TNF-α system was associated with narcolepsy in our patients.

METHODS

We first measured the plasma level of TNF α in 56 narcoleptic patients and 53 control subjects using a highly sensitive enzyme-linked immunosorbent assay. We next determined the genotype of three single nucleotide polymorphisms (SNPs) (T-1031C, C-863A, and C-857T) at the promoter region of the TNF-α gene and one missense SNP (T587G, M196R) at the exon 6 of the tumor necrosis factor receptor 2 gene, TNFR2, in a sample of 75 narcoleptic patients and 201 control subjects by direct sequencing analysis.

RESULTS

We found a significant elevation of plasma level of TNF α in patients with narcolepsy compared with the control subjects (4.64pg/mL vs 1.06pg/mL; P=.0013). However, we did not find significant differences between these two groups in the allelic and genotypic distributions of the investigated polymorphisms.

CONCLUSIONS

Our study suggests that an increased TNF-α level was associated with narcolepsy in our patients, and that chronic inflammation due to various factors might have led to the increased TNF-α levels found in our patients.

Clinical and polysomnographic course of childhood narcolepsy with cataplexy

Our aim was to investigate the natural evolution of cataplexy and polysomnographic features in untreated children with narcolepsy with cataplexy. To this end, clinical, polysomnographic, and cataplexy-video assessments were performed at diagnosis (mean age of 10 ± 3 and disease duration of 1 ± 1 years) and after a median follow-up of 3 years from symptom onset (mean age of 12 ± 4 years) in 21 children with narcolepsy with cataplexy and hypocretin 1 deficiency (tested in 19 subjects). Video assessment was also performed in two control groups matched for age and sex at first evaluation and follow-up and was blindly scored for presence of hypotonic (negative) and active movements. Patients’ data at diagnosis and at follow-up were contrasted, compared with controls, and related with age and disease duration. At diagnosis children with narcolepsy with cataplexy showed an increase of sleep time during the 24 h; at follow-up sleep time and nocturnal sleep latency shortened, in the absence of other polysomnographic or clinical (including body mass index) changes. Hypotonic phenomena and selected facial movements decreased over time and, tested against disease duration and age, appeared as age-dependent. At onset, childhood narcolepsy with cataplexy is characterized by an abrupt increase of total sleep over the 24 h, generalized hypotonia and motor overactivity. With time, the picture of cataplexy evolves into classic presentation (i.e. brief muscle weakness episodes triggered by emotions), whereas total sleep time across the 24 h decreases, returning to more age-appropriate levels.

Association analysis of the major histocompatibility complex, class II, DQ β1 gene, HLA-DQB1, with narcolepsy in Han Chinese patients from Taiwan

BACKGROUND

Narcolepsy is a rare, chronic, disabling neuropsychiatric disorder characterized by excessive daytime sleepiness, cataplexy, hypnagogic hallucinations, sleep paralysis, and abnormal rapid eye movement sleep. It is strongly associated with the HLA-DQB1(∗)06:02 allele in various ethnic groups. Our study aimed to investigate the allelic spectrum of HLA-DQB1 in a sample of Han Chinese patients with narcolepsy and control subjects from Taiwan.

METHODS

We determined the genotype of the major histocompatibility complex, class II, DQ β1 gene, HLA-DQB1, in 72 narcolepsy subjects (44 men, 28 women), including 52 narcolepsy subjects with cataplexy (narcolepsy+cataplexy), 20 narcolepsy subjects without cataplexy (narcolepsy-cataplexy), and 194 control subjects (94 men, 100 women) using a sequence-specific oligonucleotide-probe hybridization technique.

RESULTS

We found a strong HLA-DQB1(∗)06:02 association in narcolepsy+cataplexy subjects (odds ratio [OR], 321.4 [95% confidence interval {CI}, 70.7-1461.4]). The association was less prominent in narcolepsy-cataplexy subjects (OR, 6.9 [95% CI, 2.4-20.1]). In addition to the DQB1(∗)06:02, we found that (∗)03:01 also was a predisposing allele (OR, 2.0 [95% CI, 1.1-3.7]) in narcolepsy+cataplexy subjects, though the (∗)06:01 was a predisposing allele (OR, 2.8 [95% CI, 1.2-6.7]) in narcolepsy-cataplexy subjects. Furthermore, we found a significant overrepresentation of DQB1(∗)06:02 homozygotes in narcolepsy+cataplexy subjects.

CONCLUSIONS

Our data add further support to the strong association of the HLA-DQB1(∗)06:02 allele with narcolepsy, especially in narcolepsy+cataplexy patients. Our study also indicates additional HLA-DQB1 alleles may modify the presentation of narcolepsy+cataplexy patients, such as DQB1(∗)03:01 and DQB1(∗)06:01 in our study. Our results are limited by the small sample size and can only be considered as preliminary findings.

No serological evidence of influenza A H1N1pdm09 virus infection as a contributing factor in childhood narcolepsy after Pandemrix vaccination campaign in Finland

BACKGROUND

Narcolepsy cataplexy syndrome, characterised by excessive daytime sleepiness and cataplexy, is strongly associated with a genetic marker, human leukocyte antigen (HLA) DQB1*06:02. A sudden increase in the incidence of childhood narcolepsy was observed after vaccination with AS03-adjuvanted Pandemrix influenza vaccine in Finland at the beginning of 2010. Here, we analysed whether the coinciding influenza A H1N1pdm pandemic contributed, together with the Pandemrix vaccination, to the increased incidence of childhood narcolepsy in 2010. The analysis was based on the presence or absence of antibody response against non-structural protein 1 (NS1) from H1N1pdm09 virus, which was not a component of Pandemrix vaccine.

METHODS

Non-structural (NS) 1 proteins from recombinant influenza A/Udorn/72 (H3N2) and influenza A/Finland/554/09 (H1N1pdm09) viruses were purified and used in Western blot analysis to determine specific antibody responses in human sera. The sera were obtained from 45 patients who fell ill with narcolepsy after vaccination with AS03-adjuvanted Pandemrix at the end of 2009, and from controls.

FINDINGS

Based on quantitative Western blot analysis, only two of the 45 (4.4%) Pandemrix-vaccinated narcoleptic patients showed specific antibody response against the NS1 protein from the H1N1pdm09 virus, indicating past infection with the H1N1pdm09 virus. Instead, paired serum samples from patients, who suffered from a laboratory confirmed H1N1pdm09 infection, showed high levels or diagnostic rises (96%) in H1N1pdm virus NS1-specific antibodies and very high cross-reactivity to H3N2 subtype influenza A virus NS1 protein.

CONCLUSION

Based on our findings, it is unlikely that H1N1pdm09 virus infection contributed to a sudden increase in the incidence of childhood narcolepsy observed in Finland in 2010 after AS03-adjuvanted Pandemrix vaccination.

Vaccine adjuvant formulations: a pharmaceutical perspective

Formulation science is an unappreciated and often overlooked aspect in the field of vaccinology. In this review we highlight key attributes necessary to generate well characterized adjuvant formulations. The relationship between the adjuvant and the antigen impacts the immune responses generated by these complex biopharmaceutical formulations. We will use 5 well established vaccine adjuvant platforms; alum, emulsions, liposomes, PLG, and particulate systems such as ISCOMS in addition to immune stimulatory molecules such as MPL to illustrate that a vaccine formulation is more than a simple mixture of component A and component B. This review identifies the challenges and opportunities of these adjuvant platforms. As antigen and adjuvant formulations increase in complexity having a well characterized robust formulation will be critical to ensuring robust and reproducible results throughout preclinical and clinical studies.

The history of MF59(®) adjuvant: a phoenix that arose from the ashes

The first clinical trial of an MF59(®)-adjuvanted influenza vaccine (Novartis) was conducted 20 years ago in 1992. The product that emerged (Fluad(®), Novartis) was licensed first in Italy in 1997 and is now licensed worldwide in 30 countries. US licensure is expected in the coming years. By contrast, many alternative adjuvanted vaccines have failed to progress. The key decisions that allowed MF59 to succeed in such a challenging environment are highlighted here and the lessons that were learned along the way are discussed. MF59 was connected to vaccines that did not succeed and was perceived as a 'failure' before it was a success. Importantly, it never failed for safety reasons and was always well tolerated. Even when safety issues have emerged for alternative adjuvants, careful analysis of the substantial safety database for MF59 have shown that there are no significant concerns with widespread use, even in more 'sensitive' populations.

A qualitative study of the coverage of influenza vaccination on Dutch news sites and social media websites

Background

Information about influenza and the effectiveness of vaccination against influenza is largely available on the Internet, and may influence individual decision making about participation in future influenza vaccination rounds. E-health information has often been found to be inaccurate, or even to contradict Health Authority recommendations, especially when it concerns controversial topics.

Methods

By means of an online media monitoring programme, Dutch news sites and social media websites were scanned for the Dutch counterparts of the terms influenza, vaccination, vaccine and epidemic during February, March and April 2012. Data were processed with QSR NVivo 8.0 and analysed using a general inductive approach.

Results

Three overarching themes were found in both media sources: (1) the (upcoming) influenza epidemic, (2) general information regarding the virus, its prevention and treatment, and (3) uncertainty and mistrust regarding influenza vaccination. Social media tended to report earlier on developments such as the occurrence of an influenza epidemic. The greatest difference was that in social media, influenza was not considered to be a serious disease, and more opposition to the flu shot was expressed in social media, as compared to news media.

Conclusions

News media and social media discussed the same topics regarding influenza, but differed in message tone. Whereas news media reports tended to be more objective and non-judgmental, social media more critically evaluated the harmfulness of influenza and the necessity of the flu shot. Media may influence decision making and behaviours of Internet users and may thereby influence the success of vaccination campaigns and recommendations made by health authorities. Social media may be more of a problem in this sense, since it is neither controlled nor censored. Future research should investigate the actual impact of Internet media on the influenza decision making process of its users.

The autoimmune basis of narcolepsy

Narcolepsy is a neurological disorder characterized by excessive daytime sleepiness, cataplexy, hypnagonic hallucinations, sleep paralysis, and disturbed nocturnal sleep patterns. Narcolepsy is caused by the loss of hypocretin (orexin)-producing neurons in the lateral hypothalamus. Evidence, such as a strong association with HLA DQB1*06:02, strongly suggests an autoimmune basis targeting hypocretin neurons. Genome-wide association studies have strengthened the association between narcolepsy and immune system gene polymorphisms, including the identification of polymorphisms in the T cell receptor alpha locus, TNFSF4 (also called OX40L), Cathepsin H (CTSH) the purinergic receptor P2RY11, and the DNA methyltransferase DNMT1. Recently, attention has been raised regarding a spike in cases of childhood narcolepsy in 2010 following the 2009 H1N1 pandemic (pH1N1) in China and vaccination with Pandemrix, an adjuvanted H1N1 vaccine that was used in Europe. How the immune system may be involved in disease initiation and/or progression remains a challenge to researchers. Potential immunological pathways that could lead to the specific elimination of hypocretin producing neurons include molecular mimicry or bystander activation, and are likely a combination of genetic and environmental factors, such as upper airway infections.

HLA associations with tubulointerstitial nephritis with or without uveitis in Finnish pediatric population: a nation-wide study

The human leukocyte antigen (HLA) genotype has been shown to associate with tubulointerstitial nephritis (TIN) and tubulointerstitial nephritis with uveitis syndrome (TINU). The association of HLA genes with TIN was examined in this nation-wide study. HLA genotyping was performed in 31 pediatric patients with biopsy-proven TIN. All patients were examined by an ophthalmologist to diagnose possible uveitis. Class II HLA genotypes of TIN patients were compared with the Finnish reference population. We found a significant association between the HLA alleles DQA1*04:01 [risk ratio (RR) 5.0, 95% confidence interval (CI) 2.0-11.2], DQB1*04:02 (RR 2.7, 95% CI 1.4-5.3), and DRB1*08 (RR 3.8, 95% CI 1.5-8.4) and TIN. Uveitis was found in 20/31 (64.5%) patients. HLA genotyping of the TINU patients showed additional risk HLA alleles: DQA1*01:04 (RR 6.1, 95% CI 1.5-17.8), and DRB1*14 (RR 8.2, 95% CI 2.2-22.1). The alleles DQA1*01:04 (RR 8.8, 95% CI 2.2-26.5), DQA1*04:01 (RR 3.2, 95% CI 1.2-7.3), and DRB1*14 (RR 12.0, 95% CI 3.2-33.0) were more frequent in patients with TIN and chronic uveitis than in reference population. The HLA class II haplotype DQA1*04:01/DQB1:04:02/DRB1*08 was the most common combination in our study population (58.1%). None of the patients had haplotype DQA1*04:01/DQB1*06:02/DRB1*15, which is common in Finland. HLA genotype did not predict the renal outcome. We found a strong association between certain HLA genotypes both in TIN and TINU patients. The TIN/TINU-associated HLA alleles appear to vary depending on study population.

Impact of obesity in children with narcolepsy

AIMS

To evaluate the impact of obesity on clinical and sleep characteristics in a population of narcoleptic children.

METHODS

Data from the children diagnosed with idiopathic narcolepsy in the National Reference Centers for Narcolepsy were collected between 2008 and 2011. Clinical and electrophysiological characteristics were compared between obese (body mass index [BMI] greater than P97) and nonobese children.

RESULTS

The 117 children (65 boys, 59 de novo patients) had a mean age of 11.6 ± 3.1 years on diagnosis. Cataplexy was present in 81%, DQB1*0602 in 91%. Mean BMI was 23.2 ± 5.2 kg/m(2) and BMI z-score was 2.9 ± 2.6. Obesity was found in 60% with a similar prevalence in treated versus de novo patients and in patients with and without cataplexy. Sleepiness and cataplexy started earlier in obese children. Obese narcoleptic children had lower sleep efficiency, higher apnea hypopnea index and respiratory arousals index (RAI) than nonobese children. BMI z-score was positively correlated with RAI. Obese children were more tired and missed more often school than nonobese children.

CONCLUSION

Obesity affects more than 50% of narcoleptic children, mostly younger at disease onset, and has a deleterious impact on sleep quality as well as on school attendance.

ImmunoChip study implicates antigen presentation to T cells in narcolepsy

Recent advances in the identification of susceptibility genes and environmental exposures provide broad support for a post-infectious autoimmune basis for narcolepsy/hypocretin (orexin) deficiency. We genotyped loci associated with other autoimmune and inflammatory diseases in 1,886 individuals with hypocretin-deficient narcolepsy and 10,421 controls, all of European ancestry, using a custom genotyping array (ImmunoChip). Three loci located outside the Human Leukocyte Antigen (HLA) region on chromosome 6 were significantly associated with disease risk. In addition to a strong signal in the T cell receptor alpha (TRA@), variants in two additional narcolepsy loci, Cathepsin H (CTSH) and Tumor necrosis factor (ligand) superfamily member 4 (TNFSF4, also called OX40L), attained genome-wide significance. These findings underline the importance of antigen presentation by HLA Class II to T cells in the pathophysiology of this autoimmune disease.

While there is now broad consensus that narcolepsy-hypocretin deficiency results from a highly specific autoimmune attack on hypocretin cells, little is understood regarding the initiation and progression of the underlying autoimmune process. We have taken advantage of a unique high-density genotyping platform (the ImmunoChip) designed to study variants in genes known to be important to autoimmune and inflammatory diseases. Our study of nearly 2000 narcolepsy cases compared to 10,000 controls underscored important roles for HLA DQB1*06:02 and the T cell receptor alpha genes and implicated two additional genes, Cathepsin H and TNFSF4/OX40L, in disease pathogenesis. These findings are particularly important, as these encoded proteins have key roles in antigen processing, presentation, and T cell response, and they suggest that specific interactions at the immunological synapse constitute the pathway to the disease. Further studies of these genes and encoded proteins may therefore reveal the mechanism leading to this highly selective and unique autoimmune disease.

PATH Influenza Vaccine Project: accelerating the development of new influenza vaccines for low-resource countries

The 2009 influenza A/H1N1 pandemic demonstrated that a pandemic influenza virus has the potential to spread more rapidly in today's highly interconnected world than in the past. While pandemic morbidity and mortality are likely to be greatest in low-resource countries, manufacturing capacity and access to influenza vaccines predominantly exist in countries with greater resources and infrastructure. Even with recently expanded manufacturing capacity, the number of doses available within a 6-month timeframe would be inadequate to fully immunize the global population if the decision to implement a global vaccination program were made today. Improved, affordable vaccines are needed to limit the consequences of a global influenza outbreak and protect low-resource populations. PATH's Influenza Vaccine Project is supporting a range of activities in collaboration with private- and public-sector partners to advance the development of promising influenza vaccines that can be accessible and affordable for people in low-resource countries.

Assessing the safety of influenza vaccination in specific populations: children and the elderly

Comprehensive monitoring of the safety of influenza vaccines remains a public health priority, particularly as immunization coverage increases across different age groups at the global level. In this review, the authors provide state-of-the-art knowledge on the safety of influenza immunization among children and the elderly. The authors review the safety information in each group separately for inactivated and live attenuated influenza vaccines. Adverse events of special concern including febrile seizure, narcolepsy, asthma and Guillain-Barré syndrome are covered under specific considerations. The authors discuss the current status of the field, particularly the use of new technologies for influenza vaccines and their potential safety profile.

National surveillance of influenza-associated encephalopathy in Japan over six years, before and during the 2009-2010 influenza pandemic

Influenza-associated encephalopathy (IAE) is a serious complication of influenza and is reported most frequently in Japan. This paper presents an assessment of the epidemiological characteristics of influenza A (H1N1) 2009-associated encephalopathy in comparison to seasonal IAE, based on Japanese national surveillance data of influenza-like illness (ILI) and IAE during flu seasons from 2004–2005 through 2009–2010. In each season before the pandemic, 34–55 IAE cases (mean 47.8; 95% confidence interval: 36.1–59.4) were reported, and these cases increased drastically to 331 during the 2009 pandemic (6.9-fold the previous seasons). Of the 331 IAE cases, 322 cases were reported as influenza A (H1N1) 2009-associated encephalopathy. The peaks of IAE were consistent with the peaks of the influenza epidemics and pandemics. A total of 570 cases of IAE (seasonal A, 170; seasonal B, 50; influenza A (H1N1) 2009, 322; unknown, 28) were reported over six seasons. The case fatality rate (CFR) ranged from 4.8 to 18.2% before the pandemic seasons and 3.6% in the 2009 pandemic season. The CFR of pandemic-IAE was 3.7%, which is lower than that of influenza A−/B-associated encephalopathy (12.9%, p<0.001; 14.0%, p = 0.002; respectively). The median age of IAE was 7 years during the pandemic, which is higher than that of influenza A−/B-associated encephalopathy (4, p<0.001; 4.5, p = 0.006; respectively). However, the number of pandemic-IAE cases per estimated ILI outpatients peaked in the 0–4-year age group and data both before and during the pandemic season showed a U-shape pattern. This suggests that the high incidence of influenza infection in the 0–4 year age group may lead to a high incidence of IAE in the same age group in a future influenza season. Further studies should include epidemiologic case definitions and clinical details of IAE to gain a more accurate understanding of the epidemiologic status of IAE.

[Concepts, effectiveness, and perspectives of pandemic and seasonal influenza vaccines]

For the first time in history, the conditions to influence the course of an influenza pandemic through vaccination were set during the influenza A H1N1 pandemic in 2009. The specific requirements for pandemic vaccines are to be highly immunogenic in immunologically naive individuals and to be producible quickly in large quantities. In contrast, seasonal influenza vaccines induce a booster response and a broadening of preexisting immunity. In this article the concepts of seasonal and pandemic influenza vaccines and data on their immunogenicity and clinical efficacy are reviewed and discussed. In the upcoming years, seasonal influenza vaccination will continue to be based on inactivated split-virion and subunit vaccines or the live attenuated cold-adapted vaccine. The pandemic vaccines used in 2009 proved to be more immunogenic than expected from prepandemic vaccine trials, while the adverse events observed with AS03-adjuvanted vaccines call their future use into question. However, neither seasonal nor pandemic influenza vaccines can be regarded to be an ideal solution, because they have to be frequently adapted to new virus strains and they lack effectiveness in particular risk groups. They can be regarded as interim approaches to highly immunogenic vaccines that hopefully become available in the future. The underlying principles of future vaccines are also presented in this article.

Aflunov®: a vaccine tailored for pre-pandemic and pandemic approaches against influenza

INTRODUCTION

Aflunov is an egg-derived, subunit vaccine from Novartis Vaccines and Diagnostics containing 7.5 μg of hemagglutinin (HA) from the avian A/H5N1 virus and the oil-in-water adjuvant MF59.

AREAS COVERED

Aflunov behaves as a pre-pandemic vaccine. It has a good safety profile at all ages. At all ages, it induces high and persisting antibody titers and activation of HA-specific Th0/Th1 CD4(+) T cells, the levels of which correlate with the neutralizing antibody titers after a booster dose 6 months later. Aflunov triggers strong immunological memory, which persists for at least 6 - 8 years and can be rapidly boosted with a heterovariant vaccine strain, inducing very high neutralizing antibody titers within one week. These antibodies broadly and strongly cross-react with drifted H5N1 virus strains from various clades. Finally, the MF59 changes the pattern of HA recognition by antibodies that react with the HA1 more than with the HA2 region.

EXPERT OPINION

The available data show that Aflunov is a pre-pandemic vaccine suitable not only for stockpiling in case of a pandemic, but also before a pandemic is declared, with the ultimate objective of preventing the onset of an influenza pandemic.

HLA-DQ association and allele competition in Chinese narcolepsy

In Japanese, Koreans and Caucasians, narcolepsy/hypocretin deficiency is tightly associated with the DRB1*15:01-DQA1*01:02-DQB1*06:02 haplotype. Studies in African-Americans suggest a primary effect of DQB1*06:02, but this observation has been difficult to confirm in other populations because of high linkage disequilibrium between DRB1*15:01/3 and DQB1*06:02 in most populations. In this study, we studied human leucocyte antigen (HLA) class II in 202 Chinese narcolepsy patients (11% from South China) and found all patients to be DQB1*06:02 positive. Comparing cases with 103 unselected controls, and 110 and 79 controls selected for the presence of DQB1*06:02 and DRB1*15:01, we found that the presence of DQB1*06:02 and not DRB1*15:01 was associated with narcolepsy. In particular, Southern Chinese haplotypes such as the DRB1*15:01-DQA1*01:02-DQB1*06:01 and DRB1*15:01-DQA1*01:02-DQB1*05 were not associated with narcolepsy. As reported in Japanese, Koreans, African-Americans and Caucasians, additional protective effects of DQA1*01 (non-DQA1*01:02) and susceptibility effects of DQB1*03:01 were observed. These results illustrate the extraordinary conservation of HLA class II effects in narcolepsy across populations and show that DRB1*15:01 has no effect on narcolepsy susceptibility in the absence of DQB1*06:02. The results are also in line with a previously proposed 'HLA-DQ allelic competition model' that involves competition between non-DQA1*01:02, non-DQB1*06:02 'competent' (able to dimerize together) DQ1 alleles and the major DQα*01:02/ DQβ*06:02 narcolepsy heterodimer to reduce susceptibility.

Cost effectiveness of vaccination against pandemic influenza in European countries: mathematical modelling analysis

OBJECTIVE

To investigate whether a single optimal vaccination strategy exists across countries to deal with a future influenza pandemic by comparing the cost effectiveness of different strategies in various pandemic scenarios for three European countries.

DESIGN

Economic and epidemic modelling study.

SETTINGS

General populations in Germany, the Netherlands, and the United Kingdom.

DATA SOURCES

Country specific patterns of social contact and demographic data.

MODEL

An age structured susceptible-exposed-infected-recovered transmission model that describes how an influenza A virus will spread in the populations of Germany, the Netherlands, and the United Kingdom.

INTERVENTIONS

Comparison of four vaccination strategies: no vaccination, blanket vaccination, vaccination of elderly people (≥ 65 years), and vaccination of high transmitters (5-19 years). The four strategies were evaluated for scenarios in which a vaccine became available early or at the peak of the pandemic, and in which either everyone was initially susceptible or older age groups had pre-existing immunity.

MAIN OUTCOME MEASURE

Cost per quality adjusted life years (QALYs) gained.

RESULTS

All vaccination strategies were cost effective (incremental cost per QALY gained, comparing intervention with non-intervention). In scenarios where the vaccine became available at the peak of the pandemic and there was pre-existing immunity among elderly people the incremental cost effectiveness ratios for vaccinating high transmitters were €7325 (£5815; $10,470) per QALY gained for Germany, €10,216 per QALY gained for the Netherlands, and €7280 per QALY gained for the United Kingdom. The most cost effective strategy not only differed across the pandemic scenarios but also between countries. Specifically, when the vaccine was available early in the pandemic and there was no pre-existing immunity, in Germany it would be most cost effective to vaccinate elderly people ( €940 per QALY gained), whereas it would be most cost effective to vaccinate high transmitters in both the Netherlands (€525 per QALY gained) and the United Kingdom (€163 per QALY gained). This difference in optimal strategies was due to differences in the demographic characteristics of the countries: Germany has a significantly higher proportion of elderly people compared with the Netherlands and the United Kingdom.

CONCLUSIONS

No single vaccination strategy was most cost effective across countries. With aging populations, pre-existing immunity in particular could be of crucial importance for the cost effectiveness of options to mitigate a future influenza pandemic.

Advax™, a polysaccharide adjuvant derived from delta inulin, provides improved influenza vaccine protection through broad-based enhancement of adaptive immune responses

Advax™ adjuvant is derived from inulin, a natural plant-derived polysaccharide that when crystallized in the delta polymorphic form, becomes immunologically active. This study was performed to assess the ability of Advax™ adjuvant to enhance influenza vaccine immunogenicity and protection. Mice were immunized with influenza vaccine alone or combined with Advax™ adjuvant. Immuno-phenotyping of the anti-influenza response was performed including antibody isotypes, B-cell ELISPOT, CD4 and CD8 T-cell proliferation, influenza-stimulated cytokine secretion, DTH skin tests and challenge with live influenza virus. Advax™ adjuvant increased neutralizing antibody and memory B-cell responses to influenza. It similarly enhanced CD4 and CD8 T-cell proliferation and increased influenza-stimulated IL-2, IFN-γ, IL-5, IL-6, and GM-CSF responses. This translated into enhanced protection against mortality and morbidity in mice. Advax™ adjuvant provided significant antigen dose-sparing compared to influenza antigen alone. Protection could be transferred from mice that had received Advax™-adjuvanted vaccine to naïve mice by immune serum. Enhanced humoral and T-cell responses induced by Advax™-formulated vaccine were sustained 12months post-immunization. Advax™ adjuvant had low reactogenicity and no adverse events were identified. This suggests Advax™ adjuvant could be a useful influenza vaccine adjuvant.

AS03 adjuvanted AH1N1 vaccine associated with an abrupt increase in the incidence of childhood narcolepsy in Finland

Background

Narcolepsy is a chronic sleep disorder with strong genetic predisposition causing excessive daytime sleepiness and cataplexy. A sudden increase in childhood narcolepsy was observed in Finland soon after pandemic influenza epidemic and vaccination with ASO3-adjuvanted Pandemrix. No increase was observed in other age groups.

Methods

Retrospective cohort study. From January 1, 2009 to December 31, 2010 we retrospectively followed the cohort of all children living in Finland and born from January 1991 through December 2005. Vaccination data of the whole population was obtained from primary health care databases. All new cases with assigned ICD-10 code of narcolepsy were identified and the medical records reviewed by two experts to classify the diagnosis of narcolepsy according to the Brighton collaboration criteria. Onset of narcolepsy was defined as the first documented contact to health care because of excessive daytime sleepiness. The primary follow-up period was restricted to August 15, 2010, the day before media attention on post-vaccination narcolepsy started.

Findings

Vaccination coverage in the cohort was 75%. Of the 67 confirmed cases of narcolepsy, 46 vaccinated and 7 unvaccinated were included in the primary analysis. The incidence of narcolepsy was 9.0 in the vaccinated as compared to 0.7/100,000 person years in the unvaccinated individuals, the rate ratio being 12.7 (95% confidence interval 6.1–30.8). The vaccine-attributable risk of developing narcolepsy was 1∶16,000 vaccinated 4 to 19-year-olds (95% confidence interval 1∶13,000–1∶21,000).

Conclusions

Pandemrix vaccine contributed to the onset of narcolepsy among those 4 to 19 years old during the pandemic influenza in 2009–2010 in Finland. Further studies are needed to determine whether this observation exists in other populations and to elucidate potential underlying immunological mechanism. The role of the adjuvant in particular warrants further research before drawing conclusions about the use of adjuvanted pandemic vaccines in the future.