Pandemic H1N1 Vaccine Research Articles

Narcolepsy and H1N1 influenza immunology a decade later: What have we learned?

In the wake of the A/California/7/2009 H1N1 influenza pandemic vaccination campaigns in 2009-2010, an increased incidence of the chronic sleep-wake disorder narcolepsy was detected in children and adolescents in several European countries. Over the last decade, in-depth epidemiological and immunological studies have been conducted to investigate this association, which have advanced our understanding of the events underpinning the observed risk. Narcolepsy with cataplexy (defined as type-1 narcolepsy, NT1) is characterized by an irreversible and chronic deficiency of hypocretin peptides in the hypothalamus. The multifactorial etiology is thought to include genetic predisposition, head trauma, environmental triggers, and/or infections (including influenza virus infections), and an increased risk was observed following administration of the A/California/7/2009 H1N1 vaccine Pandemrix (GSK). An autoimmune origin of NT1 is broadly assumed. This is based on its strong association with a predisposing allele (the human leucocyte antigen DQB1*0602) carried by the large majority of NT1 patients, and on links with other immune-related genetic markers affecting the risk of NT1. Presently, hypotheses on the underlying potential immunological mechanisms center on molecular mimicry between hypocretin and peptides within the A/California/7/2009 H1N1 virus antigen. This molecular mimicry may instigate a cross-reactive autoimmune response targeting hypocretin-producing neurons. Local CD4+ T-cell responses recognizing peptides from hypocretin are thought to play a central role in the response. In this model, cross-reactive DQB1*0602-restricted T cells from the periphery would be activated to cross the blood-brain barrier by rare, and possibly pathogen-instigated, inflammatory processes in the brain. Current hypotheses suggest that activation and expansion of cross-reactive T-cells by H1N1/09 influenza infection could have been amplified following the administration of the adjuvanted vaccine, giving rise to a “two-hit” hypothesis. The collective in silico, in vitro, and preclinical in vivo data from recent and ongoing research have progressively refined the hypothetical model of sequential immunological events, and filled multiple knowledge gaps. Though no definitive conclusions can be drawn, the mechanistical model plausibly explains the increased risk of NT1 observed following the 2009-2010 H1N1 pandemic and subsequent vaccination campaign, as outlined in this review.

Fast Tracking-Vaccine Safety, Efficacy, and Lessons Learned: A Narrative Review.

(1) Background: The COVID-19 pandemic has led to the fast-tracked development of vaccines under emergency use authorization. In light of the growing concerns about fast-tracked vaccines, this article reviews the safety, efficacy, and lessons learned of previously fast-tracked vaccines. (2) Methods: An article search regarding the safety and efficacy of fast-tracked vaccines was done in PubMed, Embase, Web of Science, and ScienceDirect. Of the 104 results, 24 articles were included. Five articles about BiovaxID, THERATOPE®, Sipuleucel-T, and AIDSVAX were also reviewed. (3) Results: The overall efficacy was shown to be 77–100%, with seroprotection against the viruses ranging from 87 to 100%. The antibody responses for optimal protection against the viruses fall within 85–97%. Generally, the fast-tracked vaccines were well-tolerated and had few significant adverse events, except for the H1N1 pandemic vaccine and its association with narcolepsy. To have accurate, precise, and timely fast-tracked vaccines, communication, sharing resources/data, and improving the current structures/outbreak operations are crucial. (4) Conclusions: This review found the FDA’s fast-tracking process for vaccines to have rigorous standards similar to the normal process. The previous fast-tracked vaccines were safe and efficacious. The lessons drawn from previous studies highlighted the significance of planning and utilizing global resources during significant outbreaks.

Racial and Ethnic Diversity in SARS-CoV-2 Vaccine Clinical Trials Conducted in the United States.

Evidence shows that White and non-Hispanic individuals are overrepresented in clinical trials. The development of new vaccines and drugs, however, necessitates that clinical research trials include representative participants, particularly in light of evidence showing that underrepresented minorities may have a different response to certain medications and vaccines. Racial and ethnic disparities among clinical trials are multilayered and complex, and this requires action. The results of this study indicate that significant racial and ethnic disparities consistently exist among the most recent early SARS-CoV-2 vaccine clinical trials as compared to the pandemic H1N1 vaccine clinical trials of 2009. New strategies, policies, training programs, and reforms are required to address these disparities among clinical trials.

Seasonal and 2009 Pandemic H1N1 Vaccine Acceptance as a Predictor for COVID-19 Vaccine Acceptance.

The emergence of COVID-19 also began an unprecedented production and distribution of several novel COVID-19 vaccines to combat the pandemic. Unfortunately, with the history of vaccine hesitancy in the United States and abroad, concern remains regarding the ability to vaccinate enough of the population to achieve herd immunity. In this study, 101 adults were surveyed about their vaccine experience in the waiting room of their visit to a Med-Peds clinic in Albany County, NY, to gauge interest in the upcoming rollout of COVID-19 vaccines. Questions included their opinions on seasonal influenza vaccines, the 2009 H1N1 vaccine, and the COVID-19 vaccine. The results of our survey are consistent with previous studies where gaps in acceptance were notable in black populations, lower education, and individuals with public health insurance. Furthermore, 92.9% of respondents who denied getting the 2009 H1N1 pandemic vaccine also did not plan to receive the COVID-19 vaccine (p<0.05), therefore a strong correlation was found between receipt of the previous 2009 H1N1 pandemic vaccine and the COVID-19 vaccine acceptance. The qualitative results of our study revealed that COVID-19 precautions deterred people from receiving the seasonal influenza vaccine, and a lack of information on the COVID-19 vaccine caused hesitancy to receive the vaccine on behalf of patients.

Repeated Influenza Vaccination Boosts and Maintains H1N1pdm09 Neuraminidase Antibody Titers.

Antibodies to influenza surface protein neuraminidase (NA) have been found to reduce disease severity and may be an independent correlate of protection. Despite this, current influenza vaccines have no regulatory requirements for the quality or quantity of the NA antigen and are not optimized for induction of NA-specific antibodies. Here we investigate the induction and durability of NA-specific antibody titers after pandemic AS03-adjuvanted monovalent H1N1 vaccination and subsequent annual vaccination in health care workers in a five-year longitudinal study. NA-specific antibodies were measured by endpoint ELISA and functional antibodies measured by enzyme-linked lectin assay (ELLA) and plaque reduction naturalisation assay. We found robust induction of NA inhibition (NAI) titers with a 53% seroconversion rate (>4-fold) after pandemic vaccination in 2009. Furthermore, the endpoint and NAI geometric mean titers persisted above pre-vaccination levels up to five years after vaccination in HCWs that only received the pandemic vaccine, which demonstrates considerable durability. Vaccination with non-adjuvanted trivalent influenza vaccines (TIV) in subsequent influenza seasons 2010/2011 – 2013/2014 further boosted NA-specific antibody responses. We found that each subsequent vaccination increased durable endpoint titers and contributed to maintaining the durability of functional antibody titers. Although the trivalent influenza vaccines boosted NA-specific antibodies, the magnitude of fold-increase at day 21 declined with repeated vaccination, particularly for functional antibody titers. High levels of pre-existing antibodies were associated with lower fold-induction in repeatedly vaccinated HCWs. In summary, our results show that durable NA-specific antibody responses can be induced by an adjuvanted influenza vaccine, which can be maintained and further boosted by TIVs. Although NA-specific antibody responses are boosted by annual influenza vaccines, high pre-existing titers may negatively affect the magnitude of fold-increase in repeatedly vaccinated individuals. Our results support continued development and standardization of the NA antigen to supplement current influenza vaccines and reduce the burden of morbidity and mortality.

COVID-19 vaccinations among Black Asian and Minority Ethnic (BAME) groups: Learning the lessons from influenza.

BackgroundThe COVID‐19 vaccination roll‐out continues to grow at significant pace around the world. There is, however, growing concern regarding vaccine hesitancy amongst Black, Asian and Minority Ethnic (BAME) populations. Such inequalities have the potential for exposing, an already at‐risk population, further. Whilst the COVID‐19 vaccination programme is in its infancy, influenza programmes have been undertaken for over 50 years, and may provide invaluable insights. In this commentary, we aim to examine the lessons from influenza vaccinations, and how this can help reduce inequalities with COVID‐19 vaccinations.Main TextSeveral factors have been associated with both seasonal and pandemic influenza vaccine hesitancy amongst BAME groups. One of the most prevalent barriers in both types of immunisation programmes is the mistrust of medical organisations. This is often a multi‐faceted issue, with previous negative healthcare discrimination, and historical unethical practices contributing towards this scepticism. This mistrust, however, is predominantly aimed towards healthcare systems, as opposed to individual physicians. In fact, physician endorsement is often a strong driver to vaccination, with Black patients who receive this support 8 times more likely to receive seasonal influenza vaccination. On the other hand, with H1N1 pandemic influenza vaccination, social norms or community influence, was an important determinant. In both seasonal and pandemic immunisation programmes, a significant amount of concern regarding side‐effects, including misinformation, was reported amongst BAME groups.ConclusionsThe use of community‐based approaches, with local advocacy, has the potential to counteract misinformation, and concerns regarding side‐effects. Moreover, using consistent physician endorsement not only in media campaigns but also through messaging would potentially help to address longstanding healthcare mistrust amongst minority ethnic groups. Close attention regarding how the vaccination programme, and the health policies introduced as a consequence, affect BAME communities in order to prevent widening inequalities in the future.

Narcolepsy Presentation in Diverse Populations: an Update.

Purpose of ReviewWe performed a literature search to generate incidence and prevalence rates of narcolepsy in diverse populations based on current available data.Recent FindingsWith an onset in childhood, narcolepsy often has a delayed diagnosis due to symptoms of excessive daytime sleepiness not being recognized or being misdiagnosed. Clinical, electrophysiological, and biological tests are needed in order to diagnose narcolepsy. At the same time, the discovery of the link with the immunoregulatory human leukocyte antigen complex and the adverse events in relation to the H1N1 pandemic vaccines have shuffled the epidemiological numbers.SummaryIn this meta-review, we pooled incidence rates and prevalence rates reported in 30 countries or from 209 sets of data. Findings are reported per age, continent, and proxy race/ethnicity as well as period (i.e., before/after the pandemic). This meta-review showed that narcolepsy occurs in 0.87–1.21 of the world population, with specifically NT1 being investigated. Its pooled incidence rate in vaccinated samples is 1.58. There is furthermore an underreporting of narcolepsy in ethnic/race and gender minorities, of childhood narcolepsy type 2 and potential comorbid conditions masking the clinical complaints and hence timely diagnosis.

Reassessment of the risk of narcolepsy in children in England 8 years after receipt of the AS03-adjuvanted H1N1 pandemic vaccine: A case-coverage study.

BackgroundEarly studies of narcolepsy after AS03-adjuvanted pandemic A/H1N12009 vaccine (Pandemrix) could not define the duration of elevated risk post-vaccination nor the risk in children aged under 5 years who may not present until much older.Methods/FindingsClinical information and sleep test results, extracted from hospital notes at 3 large pediatric sleep centers in England between September 2017 and June 2018 for narcolepsy cases aged 4–19 years with symptom onset since January 2009, were reviewed by an expert panel to confirm the diagnosis. Vaccination histories were independently obtained from general practitioners (GPs). The odds of vaccination in narcolepsy cases compared with the age-matched English population was calculated after adjustment for clinical conditions that were indications for vaccination.GP questionnaires were returned for 242 of the 244 children with confirmed narcolepsy. Of these 5 were under 5 years, 118 were 5–11 years, and 119 were 12–19 years old at diagnosis; 39 were vaccinated with Pandemrix before onset. The odds ratio (OR) for onset at any time after vaccination was 1.94 (95% confidence interval [CI] 1.30–2.89), The elevated risk period was restricted to onsets within 12 months of vaccination (OR 6.65 [3.44–12.85]) and was highest within the first 6 months. After one year, ORs were not significantly different from 1 up to 8 years after vaccination. The ORs were similar in under five-year-olds and older ages. The estimated attributable risk was 1 in 34,500 doses. Our study is limited by including cases from only 3 sleep centers, who may differ from cases diagnosed in nonparticipating centers, and by imprecision in defining the centers’ catchment population. The potential for biased recall of onset shortly after vaccination in cases aware of the association cannot be excluded.ConclusionsIn this study, we found that vaccine-attributable cases have onset of narcolepsy within 12 months of Pandemrix vaccination. The attributable risk is higher than previously estimated in England because of identification of vaccine-attributable cases with late diagnoses. Absence of a compensatory drop in risk 1–8 years after vaccination suggests that Pandemrix does not trigger onsets in those in whom narcolepsy would have occurred later.

E. coli-Produced Monophosphoryl Lipid a Significantly Enhances Protective Immunity of Pandemic H1N1 Vaccine.

Emerging influenza viruses pose an extreme global risk to human health, resulting in an urgent need for effective vaccination against influenza infection. Adjuvants are vital components that can improve vaccine efficacy, yet only a few adjuvants have been licensed in human vaccines. Here, we investigate the adjuvant effects of Escherichia coli-produced monophosphoryl lipid A (MPL), named EcML, in enhancing the immunogenicity and efficacy of an influenza vaccine. Similar to MPL, EcML activated dendritic cells and enhanced the antigen processing of cells in vitro. Using ovalbumin (OVA) as a model antigen, EcML increased OVA-specific antibody production, cytotoxic T lymphocyte activity. The safety of EcML was demonstrated as being similar to that of MPL by showing not significant in vitro cell cytotoxicity but transient systemic inflammatory responses within 24 h in OVA immunized mice. Importantly, mice vaccinated with pandemic H1N1 (pH1N1) vaccine antigen, combined with EcML, were fully protected from pH1N1 virus infection by enhanced influenza-specific antibody titers, hemagglutination inhibition titers, and IFN-γ- secreting cells. Taken together, our results strongly suggest that EcML might be a promising vaccine adjuvant for preventing influenza virus infection.

Influenza Vaccine Efficacy and Effectiveness in Pregnant Women: Systematic Review and Meta-analysis.

Pregnant women have a high risk for complications from influenza infection, but vaccination rates within this group remain low in the US and other countries. The efficacy and effectiveness of the influenza vaccine are a key determinant of vaccine uptake. This review aimed to synthesize the available evidence on the protection of both seasonal and monovalent pandemic H1N1 (pdmH1N1) vaccine against laboratory-confirmed influenza (LCI), influenza-like illness (ILI), and respiratory illness (RI). A search of the literature was undertaken from Pubmed, Embase, ClinicalTrials.gov, and Cochrane Central Register of Controlled Trials up to Aug 1, 2018. Both observational studies and clinical trials were considered. Nineteen studies were identified from 11 countries. Women with pdmH1N1 vaccination had a lower risk of getting LCI (Relative risk [RR] 0.3, 95% confidence interval [CI] 0.26-0.35) and ILI (RR 0.15, 95% CI 0.06-0.36)). The pooled estimate from three randomized clinical trials (RR 0.47, 95% CI 0.31-0.71) and two case control studies (OR 0.37, 95% CI 0.23-0.61) showed that the seasonal vaccine was protective against LCI. The seasonal vaccine was not protective against ILI (RR 0.95, 95% CI 0.88-1.03). This association was similar for the outcome of RI (RR 0.81, 95% CI 0.55-1.20). This analysis bolsters existing evidence that influenza vaccines are effective among pregnant women. Additional public health efforts are needed to promote physician recommendations of influenza vaccination in pregnancy.

Vaccine Efficacy Induced by 2009 Pandemic H1N1 Virus-Like Particles Differs from that Induced by Split Influenza Virus

ABSTRACT Influenza virus-like particles (VLPs) vaccines are highly immunogenic, showing strong protective efficacy against homologous virus infection compared to split vaccine. However, a comparative efficacy study against heterosubtypic virus infection between VLPs and split vaccine has yet to been reported. In this study, we generated VLPs vaccine containing hemagglutinin (HA) and matrix protein (M1) of the 2009 pandemic H1N1, and investigated the protective efficacies induced by VLPs vaccine and commercial monovalent H1N1 pandemic split vaccine from Sanofi-Pasteur. Mice were intramuscularly immunized with either VLPs vaccine or split vaccine and subsequently challenge-infected with homologous virus (A/California/04/2009, H1N1) or heterosubtypic virus (A/Philippines/82, H3N2) after 4.5 months. VLPs vaccination demonstrated a higher level of protective efficacy against homologous viruses compared to split vaccine, as lessened lung viral loads and minuscule levels of proinflammatory lung cytokines IFN-gamma and IL-6 were observed. Protective efficacies were close to non-existent in VLP-immunized mice challenged with heterosubtypic viruses (H3N2). In contrast, split vaccine showed lower vaccine efficacy against homologous virus than VLP vaccine, but conferred better protection against heterosubtypic viruses through lung viral loads reduction and heightened survival rate. These results indicate that influenza VLPs provide better protective efficacy against homologous virus challenge infection, whereas split vaccine shows better protective efficacy against heterosubtypic virus challenge. Findings from the current study contribute to the rational design of vaccines conferring a broad range of protection.

Formulation Design, Optimization and In Vivo Evaluations of an α-Tocopherol-Containing Self-Emulsified Adjuvant System using Inactivated Influenza Vaccine

α-Tocopherol has been used as an immune supplement in humans, as an emulsion adjuvant component in several veterinary vaccines as well as an immunomodulatory component of AS03, an emulsion adjuvant that was used in an H1N1 pandemic vaccine (Pandemrix). AS03 is manufactured using microfluidization and high-pressure homogenization. Such high energy and complex manufacturing processes make it difficult and expensive to produce emulsion adjuvants on a large scale, especially in developing countries. In this study we have explored simpler, comparatively inexpensive methods, to formulate emulsion adjuvants containing α-tocopherol, that have the potential to be made in any well-established scale-up facility. This might facilitate producing and stock-piling adjuvant doses and therefore aide in pandemic preparedness. We used design of experiment as a tool to explore incorporating α-tocopherol into self-emulsified systems containing squalene oil and polysorbate 80. We created novel self-emulsified adjuvant systems (SE-AS) and evaluated their potency in vivo in BALB/c mice with inactivated quadrivalent influenza vaccine (QIV) and tested the cellular and humoral immune responses against the four vaccine strains.

Revisiting the pharmaceuticalisation of pandemic influenza using Lukes' framework of power.

The power of social actors to drive or block pharmaceutical uptake has been a concern in sociological debates on pharmaceuticalisation, including in the case of pandemic vaccination. We build on Steven Lukes' three-dimensional view of power to explore the 2009 H1N1 pandemic vaccination in Sweden and Denmark - two similar countries that arrived at conflicting vaccination strategies. Drawing on interviews with members of each country's pandemic steering group and on document analysis, we explore three consecutive stages of pandemic vaccination response: planning, vaccine procurement and the vaccination campaign. The paper makes two contributions to studies of pharmaceuticalisation and pandemics. Conceptually, we advocate the suitability of Lukes' framework over the 'countervailing powers' framework repeatedly used to model power in the pharmaceutical field. Empirically, our study confirms that government-appointed experts steered pandemic planning in both countries, but we show that the state, industry and the WHO also exerted power by enabling and constraining experts' decision-making, including by keeping some information secret. Furthermore, we argue that mass vaccination in Sweden was a pervasive expression of state power, in Lukes' sense, since it rested on keeping latent the tension between many individuals' health interests and the state's interests in protecting social and economic functioning.

Poly-γ-Glutamic Acid Complexed With Alum Induces Cross-Protective Immunity of Pandemic H1N1 Vaccine.

The use of a good vaccine adjuvant may induce a higher immunogenicity profile of vaccine antigens. Here, we developed a new adjuvant by combining poly-γ-glutamic acid (γ-PGA) with alum (PGA/Alum) and investigated its ability to enhance the immunogenicity and the cross-reactive efficacy of pandemic H1N1 (pH1N1) influenza vaccine antigen. PGA/Alum enhanced antigen delivery to draining lymph nodes and antigen-specific immunogenicity in mice using OVA as a model antigen. It also greatly increased OVA-specific antibody production, cytotoxic T lymphocyte (CTL) activity, and antibody-dependent cellular cytotoxicity (ADCC). These abilities of PGA/Alum improved the protective efficacy of pH1N1 vaccine antigen by increasing hemagglutination-inhibition titers, enhancing ADCC and CTL activity, and speeding viral clearance following homologous viral challenge. Importantly, the cross-protective efficacy of pH1N1 vaccine against heterologous viruses [A/Puerto Rico/8/34 (H1N1) and A/Hong Kong/1/1968 (H3N2)] was significantly enhanced by PGA/Alum, and cross-reactive ADCC and CTL activities were observed. Together, our results strongly suggest that PGA/Alum may be a promising vaccine adjuvant for preventing influenza and other infectious diseases.

The complex of poly-γ-glutamic acid and aluminum salts ameliorates the reduced efficacy of the influenza H1N1 vaccine in aged mice

Abstract Influenza is a highly contagious respiratory disease caused by the influenza A viruses and results in public health threat like seasonal epidemics and sporadic pandemics. Although vaccination is considered to be one of the most effective strategy for preventing the disease, the low efficacy of the influenza vaccine has been reported in the elderly. Here, we examined that the aging-related reduced efficacy of the influenza vaccine can be ameliorated by the complex of poly-γ-glutamic acid (γ-PGA) and alum (PGA/Alum), a novel adjuvant capable of inducing both humoral and cellular immune responses, using an aged mouse model. PGA/Alum induced activation of dendritic cells from aged mice, accompanied with increase of both expression of co-stimulatory molecules and production of pro-inflammatory cytokines. In addition, PGA/Alum enhanced the protective efficacy of pandemic influenza H1N1 (pH1N1) vaccine in aged mice, with earlier virus clearance after A/California/4/2009 (pH1N1) viral challenge, increased hemagglutination-inhibition titers, activity of cytotoxic T lymphocytes, and generation of multifunctional T lymphocytes. Taken together, these results suggest that PGA/Alum is a potent vaccine adjuvant that could improve the reduced vaccine efficacy of aging, thereby leading to prevention of influenza virus infection in the immune compromised populations.

Vitamin A Supplementation during Pregnancy Enhances Pandemic H1N1 Vaccine Response in Mothers, but Enhancement of Transplacental Antibody Transfer May Depend on When Mothers Are Vaccinated during Pregnancy

In the growing embryo, the vitamin A requirement is tightly regulated. Maternal vitamin A deficiency during pregnancy may alter maternal immune function to accommodate the fetus. Our primary objective was to determine the effect of oral vitamin A supplementation (VAS) during pregnancy and until 6 mo postpartum on pandemic H1N1-vaccine responses in mothers and their infants at 6 mo of age. In this randomized controlled clinical trial, pregnant women (n=112) during the second trimester (mean ± SD:14±1wk) were assigned to receive either an oral dose of 10,000 IU vitamin A or placebo weekly until 6 mo postpartum. During the third trimester, mothers received a single dose of inactivated pandemic H1N1-influenza vaccine. Hemagglutination-inhibition (HAI) titer was measured in cord, infant, and maternal blood samples. Multivariate regressions with adjustments were used for data analysis. Seventy-six percent of women had low plasma retinol concentrations (<1.05 μmol/L) in their second trimester. VAS of mothers increased vitamin A concentrations in cord blood by 21.4% and in colostrum by 40.7%. At 6 mo postpartum, women in the vitamin A group had 38.7% higher HAI titers and a higher proportion of HAI titer of ≥1:40 of the cutoff compared with the placebo group. A total of 54.5% of infants had an HAI titer ≥1:40 at 6 mo of age, but there was no difference in HAI titer in infants between groups. Overall, HAI in cord blood did not differ between groups, but in the placebo group, cord blood HAI was negatively associated with maternal "vaccination-to-delivery intervals" (rs=-0.401; P = 0.5), and maternal VAS increased cord blood HAI 6-fold if antenatal immunization was administered ≥10 wk before delivery. In a community with low vitamin A status, weekly maternal VAS during pregnancy and postpartum increases the breast-milk vitamin A concentration and enhances prenatal H1N1-vaccine responses in mothers, but the benefits of maternal VAS in transplacental antibody transfer may depend on the time of gestation when mothers were vaccinated. This trial was registered at clinicaltrials.gov as NCT00817661.

Narcolepsy and 2009 H1N1 pandemic vaccination in Taiwan

BackgroundSeveral European countries have observed an association between narcolepsy and H1N1 vaccines containing AS03® adjuvant in children/adolescents. In Taiwan, a nationwide campaign starting November 2009 administered H1N1 vaccines without adjuvant or with MF59® adjuvant to 67% of children and 12% of adults. MethodsFor those registered in the 2000–2012 National Health Insurance (NHI) databases, we compared age-stratified (0–4, 5–18, 19–59, and ≥60 years) incidence of first referral for a diagnostic MSLT for the pre-pandemic, pandemic/pre-vaccination, and vaccination/post-pandemic period. We also compared the odds of H1N1 vaccination in each chart-ascertained narcolepsy patient, whoever had an onset of excessive daytime sleepiness between April 2009 and December 2012, with 10 population-based controls from the NHI databases on year of birth, sex, and index date, using conditional logistic regressions. ResultsIncidence of MSLT referral for narcolepsy was highest and significantly increased in the pandemic/pre-vaccination period in the age group 5–18 (IRR 3.40, 95% confidence intervals (CI) 2.12–5.45) and 19–59 (IRR 2.90, 95% CI 1.62–5.02) years. Among 137 confirmed narcolepsy cases (86 adults and 51 children), the odds ratios (ORs) were 1.67 (95% CI 0.81–3.45) (adults) and 1.22 (95% CI 0.62–2.39) (children) for H1N1 vaccination without adjuvant, and 1.39 (95% CI 0.17–11.48) (adults) and 3.66 (95% CI 0.37–36.02) (children) with MF59® adjuvant. ConclusionNo substantial association between the use of H1N1 vaccines and narcolepsy was identified in Taiwan. Instead, the H1N1 infection itself could have played a role in triggering narcolepsy in children and young adults.

Incidence rates of narcolepsy diagnoses in Taiwan, Canada, and Europe: The use of statistical simulation to evaluate methods for the rapid assessment of potential safety issues on a population level in the SOMNIA study.

Background & objectivesVaccine safety signals require investigation, which may be done rapidly at the population level using ecological studies, before embarking on hypothesis-testing studies. Incidence rates were used to assess a signal of narcolepsy following AS03-adjuvanted monovalent pandemic H1N1 (pH1N1) influenza vaccination among children and adolescents in Sweden and Finland in 2010. We explored the utility of ecological data to assess incidence of narcolepsy following exposure to pandemic H1N1 virus or vaccination in 10 sites that used different vaccines, adjuvants, and had varying vaccine coverage.MethodsWe calculated incidence rates of diagnosed narcolepsy for periods defined by influenza virus circulation and vaccination campaign dates, and used Poisson regression to estimate incidence rate ratios (IRRs) comparing the periods during which wild-type virus circulated and after the start of vaccination campaigns vs. the period prior to pH1N1 virus circulation. We used electronic health care data from Sweden, Denmark, the United Kingdom, Canada (3 provinces), Taiwan, Netherlands, and Spain (2 regions) from 2003 to 2013. We investigated interactions between age group and adjuvant in European sites and conducted a simulation study to investigate how vaccine coverage, age, and the interval from onset to diagnosis may impact the ability to detect safety signals.ResultsIncidence rates of narcolepsy varied by age, continent, and period. Only in Taiwan and Sweden were significant time-period-by-age-group interactions observed. Associations were found for children in Taiwan (following pH1N1 virus circulation) and Sweden (following vaccination). Simulations showed that the individual-level relative risk of narcolepsy was underestimated using ecological methods comparing post- vs. pre-vaccination periods; this effect was attenuated with higher vaccine coverage and a shorter interval from disease onset to diagnosis.ConclusionsEcological methods can be useful for vaccine safety assessment but the results are influenced by diagnostic delay and vaccine coverage. Because ecological methods assess risk at the population level, these methods should be treated as signal-generating methods and drawing conclusions regarding individual-level risk should be avoided.

Controversy surrounding AEs following pandemic H1N1 vaccines

Controversy surrounding AEs following pandemic H1N1 vaccines

Seasonal Influenza Vaccine Impact on Pandemic H1N1 Vaccine Efficacy

BackgroundIn 2009, a novel influenza A (pH1N1) was identified, resulting in a pandemic with significant morbidity and mortality. A monovalent pH1N1 vaccine was separately produced in addition to the seasonal trivalent influenza vaccine. Formulation of the seasonal influenza vaccine (injectable trivalent inactivated influenza vaccine [TIV] vs. intranasal live, attenuated influenza vaccine [LAIV]) was postulated to have impacted the efficacy of the pH1N1 vaccination.MethodsWe reviewed electronic health and databases, which included vaccination records, and healthcare encounters for influenza-like illness (ILI), influenza, and pneumonia among US military members. We examined rates by vaccination type to identify factors associated with the risk for study outcomes.ResultsCompared with those receiving the seasonal influenza vaccine alone, subjects receiving the pH1N1 vaccine, either alone (RR, 0.49) or in addition to the seasonal vaccine (RR, 0.51), had an approximately 50% reduction in ILI, 88% reduction in influenza (RR, 0.11 and 0.12, respectively), and 63% reduction in pneumonia (RR, 0.37 and 0.35, respectively). There was no clinically significant difference in ILI, influenza, or pneumonia attack rates among those receiving the pH1N1 vaccine with or without presence of the seasonal vaccine. Similarly, there was no clinically relevant difference in pH1N1 effectiveness between seasonal TIV and LAIV recipients.ConclusionsDuring the 2009–2010 pandemic, the pH1N1 vaccination was effective in reducing rates of ILI, influenza, and pneumonia. Administration of the seasonal vaccine should continue without concern of potential interference with a novel pandemic vaccine, though more studies are needed to determine if this is applicable to other influenza seasons.