Comparison of the immunogenicity and safety of quadrivalent and tetravalent influenza vaccines in children and adolescents

Safety and immunogenicity of full-dose quadrivalent influenza vaccine in children 6-35 months of age in China: A randomized, double-blind, clinical trial

A half-dose influenza vaccine (7.5 μg hemagglutinin per strain) has been used for children under 3 years of age for a long time. However, several studies indicate that a full-dose influenza vaccine (15 μg hemagglutinin per strain) may bring more benefit to this population without increasing the risk of adverse reactions. We conducted a clinical study in children aged 6-35 months in China. Participants were randomized to receive two doses of full-dose quadrivalent influenza vaccine (F-QIV), half-dose quadrivalent vaccine (H-QIV), and two half-dose trivalent vaccines (H-TIV) in a 2:2:1:1 ratio. The safety and tolerability profile of the vaccine was evaluated for 6 months postvaccination. Hemagglutination inhibition (HI) antibody titers were measured for immunogenicity assessment. The primary objective was to assess whether the results of all vaccines met the criteria. A total of 1,980 participants were enrolled in the study. Both H-QIV and F-QIV were well tolerated after vaccination. Although the geometric mean increase (GMI), seroconversion rate (SCR), and seroprotection rate (SPR) for both H-QIV and F-QIV were achieved by the criteria, superior immunogenicity in terms of geometric mean titer (GMT) ratio was observed in F-QIV to H-QIV for A/H3N2 (GMT ratio (95% CI) of 1.37 (1.11 ~ 1.68)) and B/Yamagata (1.21 (1.05 ~ 1.39)). Antibody responses to the QIV were non-inferior to the response to the TIV for the matched strains. In conclusion, F-QIV and H-QIV were both safe and immunogenic for children. F-QIV induced a stronger immune response to influenza viruses and may provide more protection and benefit by promoting the use of F-QIV in children aged 6-35 months.

Synthesis and anti-influenza virus activity of substituted dibenzoxepine-based baloxavir derivatives

Seasonal influenza poses a significant threat to global public health, driving the need for effective anti-influenza agents. The PA protein, which captures the pre-mRNA cap structure, is crucial for the replication of the influenza virus and serves as an important target for developing such agents. Baloxavir, a PA inhibitor, has shown excellent activity against influenza A and B viruses. In this study, its structure was optimized using bioisosteric replacement to develop novel dibenzoxepine-based derivatives for combating influenza. As the lead compounds, ATV03 (EC50 = 0.78 ± 0.10 nM, SI > 64103) and ATV07 (EC50 = 0.78 ± 0.01 nM, SI = 31603) demonstrated excellent anti-influenza A (H3N2) activity and SI, and possessed favorable anti-influenza B activity, with 2.02 ± 0.40 nM and 2.32 ± 0.29 nM of EC50 respectively. They showed improved bioavailability and metabolic stability. Mechanism studies revealed that ATV03 and ATV07 both possessed significant activity in inhibiting PA and RdRp as well as disturbing NP. Consequently, ATV03 was selected for further investigation in the fight against seasonal and pandemic influenza due to its superior bioavailability, metabolic stability, and efficacy against multiple influenza A viruses.

Head-to-head comparison of influenza vaccines in children: a systematic review and meta-analysis

Although vaccination is considered the most effective weapon against influenza, coverage rates, national vaccination policies, and funding vary largely around the globe. Despite their huge potential for achieving herd immunity, child-focused national vaccination strategies that favor pain-free nasal vaccines are uncommon. CENTRAL, Embase, and MEDLINE were last searched on November 13, 2023. Active-controlled randomized controlled trials comparing the live-attenuated intranasal vaccine with the inactivated intramuscular influenza vaccine in children were included. Event rates of laboratory-confirmed influenza virus infection, all-cause mortality, hospitalization, serious adverse events, adverse events, and financial outcomes were extracted based on the PRISMA 2020 Guideline. PROSPERO: CRD42021285412. Pooled odds ratios (ORs) with 95% confidence intervals (CI) were calculated using the random-effects model when at least three comparable outcomes were available. We found no significant difference between quadrivalent live-attenuated intranasal and trivalent inactivated intramuscular (OR = 1.48; 95% CI 0.49-4.45) or between trivalent live-attenuated intranasal and inactivated intramuscular vaccines (OR = 0.77, CI = 0.44-1.34) regarding their efficacy. However, the subgroup analysis of large, multi-center trials indicated that the trivalent live attenuated intranasal influenza vaccine was superior to the trivalent inactivated intramuscular influenza vaccine (12,154 people, OR = 0.50, CI = 0.28-0.88). Only 23 "vaccine-related serious adverse events" were recorded among 17 833 individuals, with no significant difference between methods. The widespread initiation of pediatric national flu vaccination programs prioritizing the live-attenuated intranasal influenza vaccine would be beneficial. Multi-continent, high-quality studies that include children younger than two years old and those living in subtropical and tropical regions are needed to further enhance our understanding.

Immunogenicity and safety of inactivated quadrivalent influenza vaccine compared with the trivalent vaccine for influenza infection: an overview of systematic reviews

BACKGROUND

Influenza infection is a highly preventable transmissible viral disease associated with mild upper respiratory symptoms and more severe conditions such as lethal pneumonia. Studies have shown that a broader spectrum influenza vaccine could reduce influenza's burden of disease in low- and middle-income countries. A considerable number of systematic reviews reported that quadrivalent influenza vaccines are considered more effective compared to trivalent vaccines, hence, there is a need for an overview in order to synthesize the current evidence pertaining to the comparison between quadrivalent and trivalent inactivated influenza vaccines.

OBJECTIVE

The aim was to summarize the evidence from systematic reviews that investigated the immunogenicity and safety of the Influenza's inactivated quadrivalent vaccine (QIV) compared to the trivalent vaccine (TIV), in the general population.

METHODS

We searched articles up to December 2022 at: Web of Science, EMBASE, MEDLINE, Cochrane Library, and SCOPUS. The search strategy was conducted following the PICO model. We included systematic reviews comparing the primary outcomes of immunogenicity (seroprotection rate and seroconversion rate) and adverse events using risk ratios. The AMSTAR 2 and ROBIS were used for quality assessments, and GRADE was used for evidence certainty assessments.

FINDINGS

We included five systematic reviews, totalling 47,740 participants. The Quadrivalent Inactivated Influenza Vaccine (QIV) exhibited enhanced immunogenicity in the context of B-lineage mismatch when compared to the Trivalent Inactivated Influenza Vaccine (TIV). While the safety profile of QIV was found to be comparable to that of TIV, the QIV showed a higher incidence of solicited local pain among children and adolescents, as well as an increased frequency of local adverse events within the adult population.

CONCLUSION

Our findings suggest that the QIV provides a superior immunogenicity response compared to the TIV in all age groups evaluated, especially when a lineage mismatch occurred. The safety of QIV was considered similar to the TIV, with no serious or systemic solicited or unsolicited adverse events; tough pain at the injection site was greater for QIV. We recommend caution owing to the high risk of bias in the selection process and no protocol registration.

Immunogenicity and safety of quadrivalent inactivated influenza vaccine in children aged 6 to 35 months: A systematic review and meta-analysis

Evidence of the immunogenicity and safety of quadrivalent inactivated influenza vaccine in children aged 6 to 35 months has been emerging. To evaluate the immunogenicity and safety of quadrivalent inactivated influenza vaccine in children aged 6 to 35 months in a systematic review and meta-analysis. This meta-analysis included 12 studies with 6722 participants receiving QIV, 3575 participants receiving TIV, 4249 participants receiving full-dose QIV (F-QIV), and 3722 participants receiving half-dose QIV (H-QIV). Among children aged 6 to 35 months, QIV produces a better Immunogenicity against influenza B vaccine strains not contained in TIV. However, injection site reaction was more common for QIV, F-QIV showed superior efficacy for the B lineage, but fever and injection site pain was more frequently reported for F-QIV than H-QIV. These data support the immunogenicity and safety of quadrivalent inactivated influenza vaccine among children aged 6 to 35 months.

High prevalence of IgE sensitization to inactivated influenza vaccines, yet robust IgG4 responses, in a healthy pediatric population

BACKGROUND

Anaphylaxis following influenza vaccination is a rare but serious problem. The underlying immune responses are not well understood. This study elucidated the IgE and IgG antibody responses in healthy children and adolescents following inactivated influenza vaccines (IIVs).

METHODS

The efficacy and safety of quadrivalent IIV (QIV) and trivalent IIV (TIV) were compared in healthy subjects aged 0-18 years. Serum IIV-specific IgE, IgG, and IgG4 levels (sIgE, sIgG, and sIgG4) were measured with ImmunoCAP. Hemagglutination inhibition (HI) assay was performed for each influenza virus subtype. Sera from earlier patients who developed anaphylaxis to different IIVs were similarly tested.

RESULTS

A total of 393 subjects were enrolled: 96 were 6 months-2 years old, 100 were 3-5 years old, 100 were 6-12 years old, and 97 were 13-18 years old. No anaphylaxis was observed. Generally, QIV and TIV induced similar antibody responses. IIV-sIgE levels rose significantly after vaccination in the 6 months-2 years old and 3-5 years old groups, did not change in the 6-12 years old group, and decreased in the 13-18 years old group. In contrast, the IIV-sIgG4/sIgE ratio increased significantly after vaccination in all age groups. Sensitized subjects had significantly higher HI titers and IIV-sIgG levels in the youngest age group and higher IIV-sIgG4 levels in all age groups compared with the non-sensitized. The IIV-sIgG4/sIgE ratio in five patients with anaphylaxis was significantly lower than in age-matched healthy subjects.

CONCLUSION

IIVs induce IgE sensitization in healthy children but also robust IgG4 responses that may protect them from anaphylaxis.

Immunogenicity and safety of an egg culture-based quadrivalent inactivated non-adjuvanted subunit influenza vaccine in subjects ≥3 years: A randomized, multicenter, double-blind, active-controlled phase III, non-inferiority trial

Subunit influenza vaccine only formulated with surface antigen proteins has better safety profiles relative to split-virion influenza vaccine. Compared to the traditional quadrivalent split-virion influenza vaccine, a novel quadrivalent subunit influenza vaccine is urgently needed in China. We completed a phase 3, randomized, double-blind, active-controlled, non-inferiority clinical study at two sites in Henan Province, China. Eligible volunteers were split into four age cohorts (3-8 years, 9-17 years, 18-64 years, and ≥ 65 years, based on their dates of birth) and randomly assigned (1:1) to the subunit and the split-virion ecNAIIV4 groups. All volunteers were intramuscularly administered a single vaccine dose at baseline, and children aged 3-8 years received a boosting dose at day 28. And the immune response was evaluated by measuring hemagglutinin-inhibition antibody titers against the four vaccine strains in blood samples. Safety profiles had nonsignificant differences between the study groups in ≥ 3 years cohort. Most adverse reactions post-vaccination, both local and systemic, were mild to moderate and resolved within 3 days. And no serious adverse events occurred. The immunogenicity of the trial vaccine was non-inferior to the comparator. Further, a two-dose vaccine series can provide better seroprotection than that of a one-dose series in children aged 3-8 years, with clinically acceptable safety profiles. Clinical Trials Registration. ChiCTR2100049934.

Safety and immunogenicity of a quadrivalent inactivated subunit non-adjuvanted influenza vaccine: A randomized, double-blind, active-controlled phase 1 clinical trial

Quadrivalent influenza inactivated vaccine (IIV4) is more likely to provide wider protection against yearly circulating influenza viruses than trivalent inactivated influenza vaccine (IIV3). In this study, a total of 320 participants were allocated to four age cohorts (6-35 months, 3-8 years, 9-17 years, and ≥ 18 years; 80 participants/cohort) according to their actual date of birth. Participants in each cohort were randomly assigned to two groups to receive intramuscular injection of the trial vaccine or the comparative vaccine in a one-dose (3-8 years, 9-17 years,and ≥ 18 years) schedule on day 0 or two-dose (6-35 months cohort) schedule on day 0 and 28. The first objective is to evaluate the safety and immunogenicity of the full-dose subunit non-adjuvanted IIV4 (FD-subunit NAIIV4) we developed versus an active-control, China-licensed split-virion NAIIV4, in people ≥ 3 years. The second objective is to evaluate the safety and immunogenicity of FD-subunit NAIIV4 versus the half-dose (HD-subunit NAIIV4) in toddlers aged 6-35 months. Results showed that all adverse reactions noted were rare, mild, and self-limited. In ≥ 3 years cohorts, systemic adverse reactions in FD-subunit NAIIV4 groups were less than the active control split-virion NAIIV4 groups ([Systemic adverse reaction rates (95%CI)], 15.0 (8.6-21.4) versus 19.2(12.1-26.2), p = 0.391). The overall seroprotection efficacy after vaccination were comparable between FD-subunit NAIIV4 and the active control split-virion NAIIV4([Seroprotection rates (95%CI)], H1N1, 99.2(81.3-100.0) versus 94.9(90.9-98.9), p = 0.117; H3N2, 81.7(74.7-88.6) versus 82.1(75.1-89.0), p = 0.939; BV, 75.8(68.2-83.5) versus 74.4(66.4-82.3), p = 0.793; BY, 94.2(90.0-98.4) versus 92.3(87.5-97.1), p = 0.568). Additionally, FD-subunit NAIIV4 has comparable safety and better seroprotection versus that of the half-dose in 6-35 months toddlers groups ([Total adverse reaction rates (95%CI)], 37.5(18.5-56.5) versus 47.5(26.1-68.9), p = 0.366) ([Seroprotection rates (95%CI)], H1N1, 85(56.4-100.0) versus 75.7(47.6-100.0), p = 0.117; H3N2, 50(28.1-71.9) versus 29.7(12.2-47.3), p = 0.070; BV, 75(48.2-100.0) versus 29.7(12.2-47.3), p < 0.001; BY, 75(48.2-100.0) versus 56.8(32.5-81.0), p = 0.091). As a result, the FD-subunit NAIIV4 we developed is safe and effective to provide broader and adequate protection against the circulating influenza viruses during 2018-2019, which could be an essential component of the global preventive strategy for influenza pandemic.

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.