Quadrivalent inactivated influenza vaccine (VaxigripTetra™)

The Screening and Mechanism of Influenza-Virus Sensitive MDCK Cell Lines for Influenza Vaccine Production

Influenza is a potentially fatal acute respiratory viral disease caused by the influenza virus. Influenza viruses vary in antigenicity and spread rapidly, resulting in seasonal epidemics. Vaccination is the most effective strategy for lowering the incidence and fatality rates of influenza-related disorders, and it is also an important method for reducing seasonal influenza infections. Mammalian Madin-Darby canine kidney (MDCK) cell lines are recommended for influenza virus growth, and such cell lines have been utilized in several commercial influenza vaccine productions. The limit dilution approach was used to screen ATCC-MDCK cell line subcellular strains that are especially sensitive to H1N1, H3N2, BV, and BY influenza viruses to increase virus production, and research on influenza virus culture media was performed to support influenza virus vaccine development. We also used RNA sequencing to identify differentially expressed genes and a GSEA analysis to determine the biological mechanisms underlying the various levels of susceptibility of cells to influenza viruses. MDCK cell subline 2B6 can be cultured to increase titer and the production of the H1N1, H3N2, BV, and BY influenza viruses. MDCK-2B6 has a significantly enriched and activated in ECM receptor interaction, JAK-STAT signaling, and cytokine receptor interaction signaling pathways, which may result in increased cellular susceptibility and cell proliferation activity to influenza viruses, promote viral adsorption and replication, and elevate viral production, ultimately. The study revealed that MDCK-2B6 can increase the influenza virus titer and yield in vaccine production by increasing cell sensitivity and enhancing proliferative activity.

Humoral immune response following the inactivated quadrivalent influenza vaccination among HIV-infected and HIV-uninfected adults

BACKGROUND

A limited amount of information is available about the immunogenicity of the quadrivalent inactivated influenza vaccine among human immunodeficiency virus (HIV)-infected individuals, especially in low and middle-income countries (LMICs).

METHODS

HIV-infected adults and HIV-uninfected adults received a dose of quadrivalent inactivated influenza vaccine including strains of H1N1, H3N2, BV and BY. Enzyme-linked immunosorbent assay (ELISA) and hemagglutination-inhibition assay (HAI) were used to determine IgA, IgG antibody concentration and geometric mean titers (GMT) at day 0 and day 28, respectively. Associated factors contributing to seroconversion or GMT changes were analyzed using simple logistic regression model.

RESULTS

A total of 131 HIV-infected and 55 HIV-uninfected subjects were included in the study. In both HIV-infected and uninfected arms, IgG and IgA against influenza A and B all increased significantly at day 28 after receiving QIV (P < 0.001). GMTs of post-vaccination at day 28 showed that HIV-infected persons with CD4 + T cell counts ≤ 350 cells/mm3 were statistically less immunogenic to all strains of QIV than HIV-uninfected ones (P < 0.05). HIV-infected participants with CD4 + T cell counts ≤ 350 cells/mm3 were less likely to achieve seroconversion to QIV (H1N1, BY and BV) than HIV-uninfected individuals at day 28 after vaccination (P < 0.05). Compared with HIV-infected patients with baseline CD4 + T cell counts ≤ 350 cells/mm3, individuals with baseline CD4 + T cell counts > 350 cell/mm3 seemed more likely to generate antibody responses to H1N1 (OR:2.65, 95 %CI: 1.07-6.56) and BY (OR: 3.43, 95 %CI: 1.37-8.63), and showed a higher probability of seroconversion to BY (OR: 3.59, 95 %CI: 1.03-12.48). Compared with nadir CD4 + T cell count ≤ 350 cell/mm3, individuals with nadir CD4 + T cell count > 350 cell/mm3 showed a higher probability of seroconversion to H1N1(OR: 3.15, 95 %CI: 1.14-8.73).

CONCLUSION

Influenza vaccination of HIV-infected adults might be effective despite variable antibody responses. HIV-positive populations with CD4 + T cell counts ≤ 350 are less likely to achieve seroconversion. Further vaccination strategies could be developed for those with low CD4 T cell counts.

Post-Marketing Safety Surveillance of Quadrivalent Influenza Vaccine (VaxigripTetra) in Children Aged 6 to 35 Months in South Korea

INTRODUCTION

The quadrivalent inactivated split-virion influenza vaccine (QIV; VaxigripTetra^®) was initially licensed in South Korea in 2017 for immunization against seasonal influenza in those aged ≥ 3 years, with the indicated age subsequently lowered to include those aged ≥ 6 months in 2018. Here, to comply with South Korean licensure requirements, we undertook a post-marketing surveillance study to assess the safety of QIV in children aged 6-35 months (i.e., extension of the previous age indication to include these young children) in routine clinical practice.

METHODS

A multicenter, observational, active safety surveillance of children aged 6-35 months who received a single dose of QIV during a routine healthcare visit was undertaken in South Korea from 15 June 2018 to 14 June 2022. Solicited adverse events (AEs) and unsolicited non-serious AEs were recorded in diary cards, with serious adverse events (SAEs) notified to study investigators.

RESULTS

This safety analysis included 676 participants. No AEs led to study termination, and no SAEs were reported. The most frequent solicited injection site reaction was pain in both the ≤ 23-month (12.2% [55/450]) and ≥ 24-month (15.5% [35/226]) age groups. The most frequent solicited systemic reactions were pyrexia and somnolence in the ≤ 23-month age group (6.0% [27/450] each), and malaise (10.6% [24/226]) in the ≥ 24-month age group. Overall, 208 (30.8%) participants experienced 339 unsolicited non-serious AEs, with nasopharyngitis the most common (14.1% [95/676]), and nearly all events (98.8% [335/339]) were considered unrelated to QIV. Grade 3 solicited reactions and unsolicited non-serious AEs were reported in five (0.7%) and three (0.4%) participants, respectively, all of whom recovered by day 7 after vaccination.

CONCLUSION

This active safety surveillance study confirms that QIV is well tolerated in children aged 6-35 months in routine clinical practice in South Korea. There were no safety concerns observed in these young children.

Peptide ILE-GLU-TRP (Stemokin) Potential Adjuvant Stimulating a Balanced Immune Response

Vaccines are widely used worldwide to prevent and protect from various infections. A variety of modern approaches to developing prophylactic and therapeutic vaccines is growing. In almost all cases, adjuvants are necessary to obtain an effective immune response.This work investigated the possibility of using the pharmaceutical peptide drug Stemokin as an adjuvant stimulating a balanced Th1/Th2 response.A study was conducted to compare the activity of Stemokin versus the approved adjuvant Alhydrogel in a murine vaccination model with the approved VAXIGRIP® vaccine.The first proof-of-concept experimental study shows that the peptide Ile-Glu-Trp has the adjuvant vaccine properties and anti-HA IgG2a enhancing response, revealing a Th1- favoring balanced Th1/Th2 immunomodulation.

Post-marketing Surveillance of a Quadrivalent Influenza Vaccine (Vaxigrip Tetra) in South Korea

Introduction

In 2017, a quadrivalent inactivated split-virion influenza vaccine (QIV; Vaxigrip Tetra^®, Sanofi) was licensed in South Korea for active immunization against influenza A and influenza B viruses in individuals aged 3 years or older, which was subsequently extended to individuals aged 6 months or older in 2018. Post-marketing surveillance trials are mandatory in South Korea to retain drug licensure. Here, we assessed the safety of QIV in routine clinical practice in South Korea.

Methods

This was an open, multicenter, observational, active safety surveillance study conducted between 20 June 2017 and 19 June 2021 at 10 study sites in South Korea in individuals aged 3 years or older who received a single dose of QIV during a routine healthcare visit. The participants or their legally acceptable representatives were instructed to record any adverse reactions (solicited events) and unsolicited non-serious adverse events (AE) in diary cards, and notify study investigators in case of serious adverse events (SAE).

Results

Overall, 663 participants were included in this study. There were no AEs leading to study termination, and no SAEs reported. Injection site pain (278 [41.9%]) was the most frequent solicited injection site reaction, with myalgia (250 [37.7%]) and malaise (236 [35.6%]) the most frequent solicited systemic reactions. Grade 3 solicited injection site and systemic reactions were reported by 8 (1.2%) and 13 (2.0%) participants, respectively; most participants with solicited reactions recovered without the need for further action. Overall, 39 (5.9%) participants experienced 49 unsolicited non-serious AEs with the most frequently reported being nasopharyngitis (19 [2.9%]). Grade 3 unsolicited non-serious adverse events were reported in 1 (0.2%) participant. None of the unsolicited non-serious AEs were considered to be related to QIV.

Conclusion

This post-marketing surveillance study confirms that QIV is well tolerated and has an acceptable safety profile in routine practice in South Korea. No unexpected safety concerns were identified.

Trial Registration

ClinicalTrials.gov identifier NCT05406180.

Enhanced passive safety surveillance of a quadrivalent inactivated split virion influenza vaccine in Finland during the influenza season 2020/21

BACKGROUND

The European Medicines Agency (EMA) requires enhanced safety surveillance to be conducted for annual seasonal influenza vaccines with the aim of rapidly detecting any potential new safety concerns before the peak immunisation period of the vaccine in any given year. The aim of this study was to detect any clinically significant change in the frequency or severity of expected reactogenicity of the quadrivalent inactivated split-virion influenza vaccine (IIV4) during routine immunisation in Finland for the 2020/21 season. The primary objective was to investigate the frequency of suspected adverse drug reactions (ADRs) occurring within 7 days following vaccination.

METHODS

Enhanced passive safety surveillance of individuals vaccinated with IIV4 was conducted from October 9, 2020 to November 30, 2020 across seven sites in Finland. The vaccinee reporting rate and ADR reporting rate were calculated and compared with known or expected safety data in order to identify any clinically significant changes.

RESULTS

Data were collected from 1008 individuals with 29 vaccinees reporting 82 suspected ADRs. Of these, 28 people reported 79 suspected ADRs within 7 days following vaccination, corresponding to a vaccinee reporting rate of 2.78% (95% CI: 1.85, 3.99) (ADR reporting rate, 7.84% [95% CI: 6.25, 9.67%]). The most frequently reported ADRs were injection site reactions (vaccination site pain, vaccination site erythema and vaccination site swelling) (n = 46, 2.28%), myalgia (n = 9, 0.89%) and headache (n = 8, 0.79%). No serious suspected adverse events were reported at any point post-vaccination and ADR reporting rates were in general lower compared to those reported for IIV4 in the 2019/20 surveillance study.

CONCLUSION

No clinically significant changes in what is known or expected for IIV4 were reported for the 2020/21 season which supports the safety profile of this vaccine and will help maintain public confidence in influenza vaccination.

Recent Progress in the Discovery and Development of Monoclonal Antibodies against Viral Infections

Monoclonal antibodies (mAbs), the new revolutionary class of medications, are fast becoming tools against various diseases thanks to a unique structure and function that allow them to bind highly specific targets or receptors. These specialized proteins can be produced in large quantities via the hybridoma technique introduced in 1975 or by means of modern technologies. Additional methods have been developed to generate mAbs with new biological properties such as humanized, chimeric, or murine. The inclusion of mAbs in therapeutic regimens is a major medical advance and will hopefully lead to significant improvements in infectious disease management. Since the first therapeutic mAb, muromonab-CD3, was approved by the U.S. Food and Drug Administration (FDA) in 1986, the list of approved mAbs and their clinical indications and applications have been proliferating. New technologies have been developed to modify the structure of mAbs, thereby increasing efficacy and improving delivery routes. Gene delivery technologies, such as non-viral synthetic plasmid DNA and messenger RNA vectors (DMabs or mRNA-encoded mAbs), built to express tailored mAb genes, might help overcome some of the challenges of mAb therapy, including production restrictions, cold-chain storage, transportation requirements, and expensive manufacturing and distribution processes. This paper reviews some of the recent developments in mAb discovery against viral infections and illustrates how mAbs can help to combat viral diseases and outbreaks.

Immunogenicity and safety levels of inactivated quadrivalent influenza vaccine in healthy adults via meta-analysis

Objective: The aim of the current study was to evaluate immunogenicity and safety levels of human inactivated quadrivalent influenza vaccine (QIV) which includes two A strains (A/H1N1, A/H3N2) and two B lineages (B/Victoria, B/Yamagata) in healthy adults via meta-analysis. Methods: Searches were conducted in PubMed, Cochrane Library, ClinicalTrials.gov, and EMBASE databases published in 2011-2020 according to inclusion and exclusion criteria. The purpose was to collect and perform meta-analysis of related randomized clinical trial (RCT) data concerning safety and immunogenicity levels of human QIV compared with inactivated trivalent influenza vaccine (TIV). Results: A total of 9 literatures were included. There was no significant difference in the seroconversion(SCR) and seroprotection(SPR) between QIV and TIV for influenza A strains (A/H1N1, A/H3N2) and the B lineage included in the TIV. QIV showed superior efficacy for the B lineage not included in the TIV: SCR RR of 2.20 (95%CI: 1.44-3.37, p = .0003) and SPR RR of 1.34 (95%CI: 1.10-1.63, p = .004) for B/Victoria, and SCR RR of 1.88 (95%CI: 1.53-2.31, p < .00001) and SPR RR of 1.11 (95%CI: 1.03-1.19, p = .006) for B/Yamagata, respectively. There were no significant differences between QIV and TIV for local and systemic adverse events(AE) post-vaccination. Conclusion: In adults 18-64 years old, QIV not only produced similar immunogenicity and safety levels to TIV, but also had better immunogenicity against influenza B vaccine strains not included in TIV.

Postmarketing Safety Monitoring After Influenza Vaccination Using a Mobile Health App: Prospective Longitudinal Feasibility Study

Background

For the safety monitoring of vaccinations postlicensure, reports of adverse events after immunization (AEFIs) are crucial. New technologies such as digital mobile apps can be used as an active approach to capture these events. We therefore conducted a feasibility study among recipients of the influenza vaccination using an app for assessment of the reporting of AEFIs.

Objective

The goal of the research was to determine factors influencing adherence to and correct use of a newly developed app for individuals to report AEFI for 3 months using regular reminder functions, to identify determinants of AEFI occurrence and define reported AEFI types.

Methods

We developed the app (SafeVac) and offered it to recipients of the influenza vaccination in 3 occupational settings in fall 2018. In this prospective longitudinal feasibility study, data on AEFIs were generated through SafeVac for 3 months. Using logistic and Cox regression, we assessed associations between app adherence, correct app entry, AEFIs, and sociodemographic parameters.

Results

Of the individuals who logged into SafeVac, 61.4% (207/337) used the app throughout a 3-month period. App use adherence was negatively associated with female sex (odds ratio [OR] 0.47; CI 0.25-0.91) and correct app entry was negatively associated with older age (OR 0.96; CI 0.93-0.99) and lower education (OR 0.31; CI 0.13-0.76). AEFI occurrence was associated with female sex (hazard ratio 1.41; CI 1.01-1.96) and negatively with older age (hazard ratio 0.98; CI 0.97-0.99). The most common AEFIs reported were injection site pain (106/337), pain in extremity (103/337), and fatigue/asthenia (73/337).

Conclusions

Digital AEFI reporting was feasible with SafeVac and generated plausible results for this observation period and setting. Studies directly comparing SafeVac with conventional passive reporting schemes could determine whether such digital approaches improve completeness, timeliness, and sensitivity of vaccine vigilance. Further studies should evaluate if these results are transferable to other vaccinations and populations and if introduction of such a tool has an influence on vaccination readiness and therefore vaccine safety.

Enhanced passive safety surveillance of a trivalent and a quadrivalent influenza vaccine in Denmark and Finland during the 2018/2019 season

The European Medicines Agency requires Enhanced Passive Safety Surveillance (EPSS) for all seasonal influenza vaccines. Here, we report the EPSS results for the trivalent inactivated influenza vaccine (IIV3; Vaxigrip®) and the quadrivalent inactivated influenza vaccine (IIV4; VaxigripTetra^TM) during the 2018/19 influenza season in Denmark and Finland. The primary objective was to estimate the rates of suspected adverse reactions (ARs) occurring within 7 days following routine vaccination. Between October and November 2018, 1000 safety report cards (SRCs) for IIV3 were distributed in Denmark, and 996 SRCs for IIV4 were distributed in Finland. Participants were instructed to report any ARs by telephone or e-mail using the information provided on the SRC. All participants vaccinated with IIV3 were aged ≥18 years. Most participants vaccinated with IIV4 (95.5%) were aged 18 − 65 years, 2.2% were aged 6 months to 17 years, and 2.3% were aged >65 years. Fifty-five ARs were reported by 12 participants (1.2%) vaccinated with IIV3 and 162 ARs were reported by 53 participants (5.3%) vaccinated with IIV4. The most frequent ARs were vaccination site pain and fever for IIV3, and vaccination site pain, vaccination site inflammation, myalgia, and headache for IIV4. The 2018/19 AR rates for IIV3 were comparable to 2017/18 rates. The 2018/19 AR rates for IIV4 were higher than those in 2017/18 but were still lower than the expected AR rates listed in the IIV4 Summary of Product Characteristics. In conclusion, the 2018/19 EPSS showed no clinically significant change from the expected safety profiles of IIV3 and IIV4 vaccines.

Active-controlled phase III study of an egg-cultivated quadrivalent inactivated split-virion influenza vaccine (GC3110A) in healthy Korean children aged 6-35 months

The inactivated trivalent influenza vaccine (TIV) offers limited protection when two influenza B lineages co-circulate or when there is a vaccine mismatch (i.e., discordance in the predominant circulating B strain and WHO-recommended B strain). Inactivated quadrivalent influenza vaccine (QIV) may reduce the burden of influenza. Here, we report the results of a phase 3 clinical trial that evaluated the immunogenicity and safety of a novel QIV, GC3110A, in Korean children aged 6-35 months, which has been approved and is currently in use in Korea. The study involved two parts. In Part 1, the safety of GC3110A was evaluated in 10 subjects. After none of the subjects reported grade 3 adverse events (AEs), we proceeded to Part 2. Part 2 was a randomized, double-blind, multicenter phase 3 trial wherein we compared the immunogenicity and safety of GC3110A with those of a licensed control TIV. Immunogenicity was evaluated by measuring hemagglutination inhibition titers. The 200 participants enrolled in Part 2 were randomized in a 4:1 ratio to receive GC3110A or control TIV. The study vaccine group met both primary (i.e., the lower limit of 95% confidence interval [CI] of the seroconversion rate exceeds 40% for four strains) and secondary (i.e., the lower limit of 95% CI of the seroprotection rate exceeds 70% for four strains) immunogenicity endpoints. There was no significant between-group difference in the seroconversion rate, seroprotection rate, and geometric mean titer for the shared strains. However, the study vaccine group demonstrated significantly higher immunity for the additional strain B/Yamagata. In the safety analysis, there was no significant between-group difference in the proportion of participants with solicited local AEs, solicited systemic AEs, and unsolicited AEs. In conclusion, the results indicate that GC3110A has comparable immunogenicity and safety to those of TIV. Clinical Trial Registry Number: NCT03285997.

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.

Adenovirus delivery of encoded monoclonal antibody protects against different types of influenza virus infection

Due to the high mutation and recombination rates of the influenza virus, current clinically licensed influenza vaccines and anti-influenza drugs provide limited protection against the emerging influenza virus epidemic. Therefore, universal influenza vaccines with high efficacy are urgently needed to ensure human safety and health. Passive immunization of influenza broadly neutralizing antibodies may become an ideal option for controlling influenza infection. CR9114 isolated from the peripheral blood mononuclear cells of healthy donors is a broadly neutralizing monoclonal antibody that targets different types of influenza viruses. As the adenovirus vector is one of the most promising delivery vehicles, we employed the chimpanzee adenoviral vector, AdC68, to express CR9114 as a universal anti-influenza vaccine, termed AdC68-CR9114, and evaluated its antibody expression and its broad spectrum of prophylactic and therapeutic effects in animal models. Based on our findings, AdC68-CR9114-infected cell expressed the broadly neutralizing antibody at a high level in vitro and in vivo, exhibited biological functions, and protected mice from different types of influenza virus infection at different time points. The findings from this study shed light on a new strategy for controlling and preventing influenza infection.

Immunogenicity and safety of a multi-dose quadrivalent inactivated influenza vaccine in individuals aged 6 months to 17 years: a randomized phase III trial

Annual vaccination is the most effective way to prevent seasonal influenza. Influenza vaccines in multi-dose vial (MDV) formats can facilitate timely vaccination of large populations by reducing per-dose costs and cold storage requirements compared to single-dose pre-filled syringe (PFS) formats. MDV vaccines require thiomersal or another preservative to prevent microbial contamination. We conducted a randomized, open-label trial in 302 healthy subjects aged 6 months to 17 years to evaluate the immunogenicity and safety of a quadrivalent influenza vaccine (QIV) in a thiomersal-containing MDV format compared to the licensed thiomersal-free PFS format. Subjects were randomly assigned in a 1:1 ratio to receive the MDV (n = 153) or PFS (n = 149) format. Post-vaccination hemagglutination inhibition titers for all four vaccine strains were ≥4.9-fold higher than baseline titers with no difference in magnitude between the MDV and PFS groups. Seroconversion rates per strain were also comparable between the two groups. There were no differences in reactogenicity or safety between the two vaccine formats. These results showed that the MDV format of QIV was as safe and immunogenic as the PFS format in infants, children, and adolescents. These findings support the use of MDV QIV as a resource-saving alternative for seasonal influenza vaccination.

Enhanced passive safety surveillance of three marketed influenza vaccines in the UK and the Republic of Ireland during the 2017/18 season

Safety surveillance is required for each season’s influenza vaccines to rapidly detect and evaluate potential new safety concerns before the peak period of immunization. Here we report the results of an enhanced passive safety surveillance for a trivalent split-virion inactivated influenza vaccine (IIV3; Vaxigrip®), an intradermal version of this vaccine (IIV3-ID; Intanza® 15 µg), and a recently licensed quadrivalent version (IIV4; VaxigripTetra^TM) during the 2017/18 influenza season in the UK and Republic of Ireland. The primary objective was to determine the rates of adverse reactions (ARs) occurring within 7 days following routine vaccination. Between September and November 2017, 979 safety report cards were distributed to vaccinees receiving IIV3-ID, 1005 to those receiving IIV3, and 957 to those receiving IIV4. At least one AR was reported by 28 participants (2.9%) vaccinated with IIV3-ID, 14 participants (1.4%) vaccinated with IIV3, and 20 participants (2.1%) vaccinated with IIV4. The most frequent ARs were injection-site reactions and headache. One participant vaccinated with IIV3-ID reported two suspected serious ARs (dyskinesia and a shock symptom), although these could not be confirmed as vaccine-related. Rates of ARs for IIV3 and IIV3-ID for 2017/18 did not differ from the 2016/17 rates. For IIV4, in its first season since licensure, AR frequencies were similar to those in the Summary of Product Characteristics. In conclusion, no change was found compared to the known or expected AR rates for IIV3, IIV3-ID, or IIV4 during the 2017/18 season.

[Quadrivalent influenza vaccine: What is changed and what are the benefits?]

Currently, circulating viruses responsible for annual seasonal influenza epidemics belong to two influenza A subtypes, A(H1N1) and A(H3N2), and to two antigenically distinct type B lineages, B/Yamagata and B/Victoria lineages. Like diseases due to influenza A virus, influenza B virus diseases may have severe consequences and should be prevented. Until now, in France, the vaccines used to prevent seasonal influenza were trivalent, systematically targeting viruses belonging to both A subtypes and to one or other of the B lineages. The protective efficacy of trivalent vaccines is diminished during the seasons when viruses belonging to both B lineages cocirculated or when the circulating dominant type B virus belonged to a lineage different from that targeted by the vaccine strain. By targeting viruses belonging to both B lineages, quadrivalent vaccines improve the antigenic concordance between circulating and vaccine type B strains. Three inactivated quadrivalent vaccines are authorized for marketing in France and should be available for the 2018-2019 season. It is expected that, by providing enlarged protection, these quadrivalent influenza vaccines will improve vaccine efficacy, the confidence in immunization of the public, the satisfaction of health professionals, and ultimately will help to complete immunization coverage.

[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.

Immunogenicity and Safety of the New Inactivated Quadrivalent Influenza Vaccine Vaxigrip Tetra: Preliminary Results in Children ≥6 Months and Older Adults

Since the mid-1980s, two lineages of influenza B viruses have been distinguished. These can co-circulate, limiting the protection provided by inactivated trivalent influenza vaccines (TIVs). This has prompted efforts to formulate quadrivalent influenza vaccines (QIVs), to enhance protection against circulating influenza B viruses. This review describes the results obtained from seven phase III clinical trials evaluating the immunogenicity, safety, and lot-to-lot consistency of a new quadrivalent split-virion influenza vaccine (Vaxigrip Tetra®) formulated by adding a second B strain to the already licensed TIV. Since Vaxigrip Tetra was developed by means of a manufacturing process strictly related to that used for TIV, the data on the safety profile of TIV are considered supportive of that of Vaxigrip Tetra. The safety and immunogenicity of Vaxigrip Tetra were similar to those of the corresponding licensed TIV. Moreover, the new vaccine elicits a superior immune response towards the additional strain, without affecting immunogenicity towards the other three strains. Vaxigrip Tetra is well tolerated, has aroused no safety concerns, and is recommended for the active immunization of individuals aged ≥6 months. In addition, preliminary data confirm its immunogenicity and safety even in children aged 6-35 months and its immunogenicity in older subjects (aged 66-80 years).