Evidence update: GlaxoSmithKline's inactivated quadrivalent influenza vaccines

Influenza vaccine: a review on current scenario and future prospects

Vaccination is a crucial tool in preventing influenza, but it requires annual updates in vaccine composition due to the ever-changing nature of the flu virus. While healthcare and economic burdens have reduced, the virus remains a challenge. Research conducted over the past decade has revealed pathways for improvement through both basic and clinical studies. Viral surveillance plays a vital role in the better selection of candidate viruses for vaccines and the early detection of drug-resistant strains.This page offers a description of future vaccine developments and an overview of current vaccine options. In the coming years, we anticipate significant changes in vaccine production, moving away from traditional egg-based methods towards innovative technologies such as DNA and RNA vaccines. These newer approaches offer significant advantages over traditional egg-based and cell culture-based influenza vaccine manufacturing.

Influenza-Associated Excess Mortality by Age, Sex, and Subtype/Lineage: Population-Based Time-Series Study With a Distributed-Lag Nonlinear Model

BACKGROUND

Accurate estimation of the influenza death burden is of great significance for influenza prevention and control. However, few studies have considered the short-term harvesting effects of influenza on mortality when estimating influenza-associated excess deaths by cause of death, age, sex, and subtype/lineage.

OBJECTIVE

This study aimed to estimate the cause-, age-, and sex-specific excess mortality associated with influenza and its subtypes and lineages in Guangzhou from 2015 to 2018.

METHODS

Distributed-lag nonlinear models were fitted to estimate the excess mortality related to influenza subtypes or lineages for different causes of death, age groups, and sex based on daily time-series data for mortality, influenza, and meteorological factors.

RESULTS

A total of 199,777 death certificates were included in the study. The average annual influenza-associated excess mortality rate (EMR) was 25.06 (95% empirical CI [eCI] 19.85-30.16) per 100,000 persons; 7142 of 8791 (81.2%) deaths were due to respiratory or cardiovascular mortality (EMR 20.36, 95% eCI 16.75-23.74). Excess respiratory and cardiovascular deaths in people aged 60 to 79 years and those aged ≥80 years accounted for 32.9% (2346/7142) and 63.7% (4549/7142) of deaths, respectively. The male to female ratio (MFR) of excess death from respiratory diseases was 1.34 (95% CI 1.17-1.54), while the MFR for excess death from cardiovascular disease was 0.72 (95% CI 0.63-0.82). The average annual excess respiratory and cardiovascular mortality rates attributed to influenza A (H3N2), B/Yamagata, B/Victoria, and A (H1N1) were 8.47 (95% eCI 6.60-10.30), 5.81 (95% eCI 3.35-8.25), 3.68 (95% eCI 0.81-6.49), and 2.83 (95% eCI -1.26 to 6.71), respectively. Among these influenza subtypes/lineages, A (H3N2) had the highest excess respiratory and cardiovascular mortality rates for people aged 60 to 79 years (20.22, 95% eCI 14.56-25.63) and ≥80 years (180.15, 95% eCI 130.75-227.38), while younger people were more affected by A (H1N1), with an EMR of 1.29 (95% eCI 0.07-2.32). The mortality displacement of influenza A (H1N1), A (H3N2), and B/Yamagata was 2 to 5 days, but 5 to 13 days for B/Victoria.

CONCLUSIONS

Influenza was associated with substantial mortality in Guangzhou, occurring predominantly in the elderly, even after considering mortality displacement. The mortality burden of influenza B, particularly B/Yamagata, cannot be ignored. Contrasting sex differences were found in influenza-associated excess mortality from respiratory diseases and from cardiovascular diseases; the underlying mechanisms need to be investigated in future studies. Our findings can help us better understand the magnitude and time-course of the effect of influenza on mortality and inform targeted interventions for mitigating the influenza mortality burden, such as immunizations with quadrivalent vaccines (especially for older people), behavioral campaigns, and treatment strategies.

An Overview of Influenza Viruses and Vaccines

Influenza remains one of the major public health concerns because it causes annual epidemics and can potentially instigate a global pandemic. Numerous countermeasures, including vaccines and antiviral treatments, are in use against seasonal influenza infection; however, their effectiveness has always been discussed due to the ongoing resistance to antivirals and relatively low and unpredictable efficiency of influenza vaccines compared to other vaccines. The growing interest in vaccines as a promising approach to prevent and control influenza may provide alternative vaccine development options with potentially increased efficiency. In addition to currently available inactivated, live-attenuated, and recombinant influenza vaccines on the market, novel platforms such as virus-like particles (VLPs) and nanoparticles, and new vaccine formulations are presently being explored. These platforms provide the opportunity to design influenza vaccines with improved properties to maximize quality, efficacy, and safety. The influenza vaccine manufacturing process is also moving forward with advancements relating to egg- and cell-based production, purification processes, and studies into the physicochemical attributes and vaccine degradation pathways. These will contribute to the design of more stable, optimized vaccine formulations guided by contemporary analytical testing methods and via the implementation of the latest advances in the field.

Advances in Development and Application of Influenza Vaccines

Influenza A virus is one of the most important zoonotic pathogens that can cause severe symptoms and has the potential to cause high number of deaths and great economic loss. Vaccination is still the best option to prevent influenza virus infection. Different types of influenza vaccines, including live attenuated virus vaccines, inactivated whole virus vaccines, virosome vaccines, split-virion vaccines and subunit vaccines have been developed. However, they have several limitations, such as the relatively high manufacturing cost and long production time, moderate efficacy of some of the vaccines in certain populations, and lack of cross-reactivity. These are some of the problems that need to be solved. Here, we summarized recent advances in the development and application of different types of influenza vaccines, including the recent development of viral vectored influenza vaccines. We also described the construction of other vaccines that are based on recombinant influenza viruses as viral vectors. Information provided in this review article might lead to the development of safe and highly effective novel influenza vaccines.

Smoking Cessation/Vaccinations

More than one-third of patients with chronic obstructive pulmonary disease (COPD) continue to smoke cigarettes despite knowing they have the disease. This behavior has a negative impact on prognosis and progression, as repeated injury enhances the pathobiological mechanisms responsible for the disease. A combination of counseling plus pharmacotherapy is the most effective cessation treatment of smokers with COPD, and varenicline seems to be the most effective pharmacologic intervention. Preventing exacerbations in patients with COPD is a major goal of treatment, and vaccination against influenza and pneumococcus is an effective preventive strategy to achieve this goal.

Chimeric Hemagglutinin-Based Influenza Virus Vaccines Induce Protective Stalk-Specific Humoral Immunity and Cellular Responses in Mice

The high variation of the influenza virus hemagglutinin (HA), particularly of its immunodominant head epitopes, makes it necessary to reformulate seasonal influenza virus vaccines every year. Novel influenza virus vaccines that redirect the immune response toward conserved epitopes of the HA stalk domain should afford broad and durable protection. Sequential immunization with chimeric HAs (cHAs) that express the same conserved HA stalk and distinct exotic HA heads has been shown to elicit high levels of broadly cross-reactive Abs. In the current mouse immunization studies, we tested this strategy using inactivated split virion cHA influenza virus vaccines (IIV) without adjuvant or adjuvanted with AS01 or AS03 to measure the impact of adjuvant on the Ab response. The vaccines elicited high levels of cross-reactive Abs that showed activity in an Ab-dependent, cell-mediated cytotoxicity reporter assay and were protective in a mouse viral challenge model after serum transfer. In addition, T cell responses to adjuvanted IIV were compared with responses to a cHA-expressing live attenuated influenza virus vaccine (LAIV). A strong but transient induction of Ag-specific T cells was observed in the spleens of mice vaccinated with LAIV. Interestingly, IIV also induced T cells, which were successfully recalled upon viral challenge. Groups that received AS01-adjuvanted IIV or LAIV 4 wk before the challenge showed the lowest level of viral replication (i.e., the highest level of protection). These studies provide evidence that broadly cross-reactive Abs elicited by cHA vaccination demonstrate Fc-mediated activity. In addition, cHA vaccination induced Ag-specific cellular responses that can contribute to protection upon infection.

[Seasonal flu vaccination for older people: Evaluation of the quadrivalent vaccine. Positioning report]

Influenza is a significant health problem, particularly in those persons susceptible to having associated complications, older people, children less than 2 years, patients with chronic diseases, immunocompromised patients, and pregnant women. But influenza also has a large impact on the health system, with an increase in the healthcare demand and a spectacular increase in outpatient visits, overloading the emergency and hospital services. During epidemic outbreaks, the hospital admission rates of people over 65 years are at a maximum, and the mortality notified for the 2017/2018 influenza season was 960 deaths. The seasonal anti-influenza vaccine is the method with a better cost-effective ratio of primary prevention of influenza, reducing associated respiratory diseases, the number of hospital admissions, and deaths in high risk individuals, as well as work absenteeism in adults. In the last few years, influenza B has received little attention in the scientific literature, although in the periods between epidemics influenza B can be one of the main causes of seasonal epidemics, causing considerable morbidity and mortality and an increase in costs. The quadrivalent vaccine has a second-line immunological protection against influenza B, and according to a critical review of the scientific literature, it provides wider protection without affecting immunogenicity of the other three vaccine strains common to the trivalent and tetravalent vaccine. The quadrivalent vaccine is cost-effective in reducing the number of influenza cases, and is always a worthwhile intervention, with a significant cost saving for the health system and for society, by reducing the hospital admission rates and mortality associated with the complications of influenza. Supplement information: This article is part of a supplement entitled 'Seasonal flu vaccination for older people: Evaluation of the quadrivalent vaccine' which is sponsored by Sanofi-Aventis, S.A.

Significant circulation of influenza B viruses mismatching the recommended vaccine-lineage in South Korea, 2007-2014

We aimed to characterize the lineages of influenza B viruses obtained from clinical specimens during the 2007-2014 seasons in South Korea. RT-PCR for the partial hemagglutinin gene of influenza B virus was performed on laboratory-confirmed influenza B samples from the 2007-2008 season to 2013-2014 season. A phylogenetic tree was generated, and current influenza vaccine strains for the Northern Hemisphere were used as representative strains of Victoria and Yamagata lineages. A total of 571 influenza B virus sequences were analyzed. During the 2009-2010 season, most of the circulating influenza B viruses matched the vaccine strain; 91.0% (91/100) of viruses belonged to the Victoria lineage. In the 2007-2008, 2011-2012, and 2013-2014 seasons, co-circulation of each influenza B lineage was found with a match ratio to the vaccine strain of 53.2% (42/79), 40.9% (63/154), and 58.3% (134/230), respectively. Overall, 41.7% (238/571) of the circulating influenza B viruses belonged to the lineage mismatching the vaccine strain. During the seven influenza seasons, influenza B epidemics were substantial in four seasons in South Korea. Significant mismatches of the vaccine and lineage of the circulating influenza B viruses were found. The current trivalent influenza vaccine may not be fully suitable for effective protection against influenza B.

Influenza surveillance in Western Turkey in the era of quadrivalent vaccines: A 2003-2016 retrospective analysis

Human influenza is predominantly caused by influenza A virus (IAV) - A/H1N1 and/or A/H3N2 - and influenza B virus (IBV) - B/Victoria and/or B/Yamagata, which co-circulate each season. Influenza surveillance provides important information on seasonal disease burden and circulation, and vaccine content for the following season. To study the circulating influenza subtypes/lineages in western Turkey. Community-based sentinel surveillance results during 2003-2016 (weeks 40-20 each season; but week 21, 2009 through week 20, 2010 during the pandemic) were analyzed. Nasal/nasopharyngeal swabs from patients with influenza-like illness were tested for influenza virus and characterized as A/H1N1, A/H3N2, or IBV. A subset of IBV samples was further characterized as B/Victoria or B/Yamagata. Among 14,429 specimens (9,766 collected during interpandemic influenza seasons; 4,663 during the 2009-2010 pandemic), 3,927 (27.2%) were positive. Excluding the pandemic year (2009-2010), 645 (27.4%) samples were characterized as A/H1N1 or A/H1N1/pdm09, 958 (40.7%) as A/H3N2, and 752 (31.9%) as IBV, but the dominant subtype/lineage varied widely each season. During the pandemic year (2009-2010), 98.3% of cases were A/H1N1/pdm09. IBV accounted for 0-60.2% of positive samples each season. The IBV lineages in circulation matched the vaccine IBV lineage >50% in six seasons and <50% in four seasons; with an overall mismatch of 49.7%. IBV cases tended to peak later than IAV cases within seasons. These results have important implications for vaccine composition and optimal vaccination timing. Quadrivalent vaccines containing both IBV lineages can reduce B-lineage mismatch, thus reducing the burden of IBV disease.

Influenza Vaccination in Patients with Common Variable Immunodeficiency (CVID)

PURPOSE OF REVIEW

Vaccination against influenza in patients with primary antibody deficiency is recommended. Common variable immunodeficiency (CVID) is the most frequent and clinically relevant antibody deficiency disease and is by definition characterized by an impaired vaccination response. The purpose of this review is to present the current knowledge of humoral and cellular vaccine response to influenza in CVID patients.

RECENT FINDINGS

Studies conducted in CVID patients demonstrated an impaired humoral response upon influenza vaccination. Data on cellular immune response are in part conflicting, with two out of three studies showing responses similar to healthy controls. Available data suggest a benefit from influenza vaccination in CVID patients. Therefore, annual influenza vaccination in patients and their close household contacts is recommended.

Cost-effectiveness analysis of quadrivalent seasonal influenza vaccines in England

BACKGROUND

As part of the national seasonal influenza vaccination programme in England and Wales, children receive a quadrivalent vaccine offering protection against two influenza A strains and two influenza B strains. Healthy children receive a quadrivalent live attenuated influenza vaccine (QLAIV), whilst children with contraindications receive the quadrivalent inactivated influenza vaccine (QIIV). Individuals aged younger than 65 years in the clinical risk populations and elderly individuals aged 65+ years receive either a trivalent inactivated influenza vaccine (TIIV) offering protection from two A strains and one B strain or the QIIV at the choice of their general practitioner. The cost-effectiveness of quadrivalent vaccine programmes is an open question. The original analysis that supported the paediatric programme only considered a trivalent live attenuated vaccine (LAIV). The cost-effectiveness of the QIIV to other patients has not been established. We sought to estimate the cost-effectiveness of these programmes, establishing a maximum incremental total cost per dose of quadrivalent vaccines over trivalent vaccines.

METHODS

We used the same mathematical model as the analysis that recommended the introduction of the paediatric influenza vaccination programme. The incremental cost of the quadrivalent vaccine is the additional cost over that of the existing trivalent vaccine currently in use.

RESULTS

Introducing quadrivalent vaccines can be cost-effective for all targeted groups. However, the cost-effectiveness of the programme is dependent on the choice of target cohort and the cost of the vaccines: the paediatric programme is cost-effective with an increased cost of £6.36 per dose, though an extension to clinical risk individuals younger than 65 years old and further to all elderly individuals means the maximum incremental cost is £1.84 and £0.20 per dose respectively.

CONCLUSIONS

Quadrivalent influenza vaccines will bring substantial health benefits, as they are cost-effective in particular target groups.

A review of the value of quadrivalent influenza vaccines and their potential contribution to influenza control

The contribution of influenza B to the seasonal influenza burden varies from year-to-year. Although 2 antigenically distinct influenza B virus lineages have co-circulated since 2001, trivalent influenza vaccines (TIVs) contain antigens from only one influenza B virus. B-mismatch or co-circulation of both B lineages results in increased morbidity and mortality attributable to the B lineage absent from the vaccine. Quadrivalent vaccines (QIVs) contain both influenza B lineages. We reviewed currently licensed QIVs and their value by focusing on the preventable disease burden. Modeling studies support that QIVs are expected to prevent more influenza cases, hospitalisations and deaths than TIVs, although estimates of the case numbers prevented vary according to local specificities. The value of QIVs is demonstrated by their capacity to broaden the immune response and reduce the likelihood of a B-mismatched season. Some health authorities have preferentially recommended QIVs over TIVs in their influenza prevention programmes.

Seasonal influenza vaccination in patients with COPD: a systematic literature review

BACKGROUND

Influenza is a frequent cause of exacerbations of chronic obstructive pulmonary disease (COPD). Exacerbations are associated with worsening of the airflow obstruction, hospitalisation, reduced quality of life, disease progression, death, and ultimately, substantial healthcare-related costs. Despite longstanding recommendations to vaccinate vulnerable high-risk groups against seasonal influenza, including patients with COPD, vaccination rates remain sub-optimal in this population.

METHODS

We conducted a systematic review to summarise current evidence from randomised controlled trials (RCTs) and observational studies on the immunogenicity, safety, efficacy, and effectiveness of seasonal influenza vaccination in patients with COPD. The selection of relevant articles was based on a three-step selection procedure according to predefined inclusion and exclusion criteria. The search yielded 650 unique hits of which 48 eligible articles were screened in full-text.

RESULTS

Seventeen articles describing 13 different studies were found to be pertinent to this review. Results of four RCTs and one observational study demonstrate that seasonal influenza vaccination is immunogenic in patients with COPD. Two studies assessed the occurrence of COPD exacerbations 14 days after influenza vaccination and found no evidence of an increased risk of exacerbation. Three RCTs showed no significant difference in the occurrence of systemic effects between groups receiving influenza vaccine or placebo. Six out of seven studies on vaccine efficacy or effectiveness indicated long-term benefits of seasonal influenza vaccination, such as reduced number of exacerbations, reduced hospitalisations and outpatient visits, and decreased all-cause and respiratory mortality.

CONCLUSIONS

Additional large and well-designed observational studies would contribute to understanding the impact of disease severity and patient characteristics on the response to influenza vaccination. Overall, the evidence supports a positive benefit-risk ratio for seasonal influenza vaccination in patients with COPD, and supports current vaccination recommendations in this population.

Cost-Utility of Quadrivalent Versus Trivalent Influenza Vaccine in Germany, Using an Individual-Based Dynamic Transmission Model

BACKGROUND

Seasonal influenza infection is primarily caused by circulation of two influenza A strain subtypes and strains from two B lineages that vary each year. Trivalent influenza vaccine (TIV) contains only one of the two B-lineage strains, resulting in mismatches between vaccine strains and the predominant circulating B lineage. Quadrivalent influenza vaccine (QIV) includes both B-lineage strains. The objective was to estimate the cost-utility of introducing QIV to replace TIV in Germany.

METHODS

An individual-based dynamic transmission model (4Flu) using German data was used to provide realistic estimates of the impact of TIV and QIV on age-specific influenza infections. Cases were linked to health and economic outcomes to calculate the cost-utility of QIV versus TIV, from both a societal and payer perspective. Costs and effects were discounted at 3.0 and 1.5 % respectively, with 2014 as the base year. Univariate and probabilistic sensitivity analyses were conducted.

RESULTS

Using QIV instead of TIV resulted in additional quality-adjusted life-years (QALYs) and cost savings from the societal perspective (i.e. it represents the dominant strategy) and an incremental cost-utility ratio (ICUR) of €14,461 per QALY from a healthcare payer perspective. In all univariate analyses, QIV remained cost-effective (ICUR <€50,000). In probabilistic sensitivity analyses, QIV was cost-effective in >98 and >99 % of the simulations from the societal and payer perspective, respectively.

CONCLUSION

This analysis suggests that QIV in Germany would provide additional health gains while being cost-saving to society or costing €14,461 per QALY gained from the healthcare payer perspective, compared with TIV.