Modification of the vaccine manufacturing process improves the pyrogenicity profile of inactivated influenza vaccines in young children.

BACKGROUND: There were increased reports of fevers and febrile reactions in young children (particularly children aged <5 years) receiving the Seqirus/CSL Southern Hemisphere 2010 trivalent inactivated influenza vaccine (IIV3). Modifying the vaccine manufacturing process by increasing the minimum concentration of splitting agent (sodium taurodeoxycholate [TDOC]) from 0.5% w/v to 1.5% w/v for all strains resolved this issue. The current analysis compared fever rates in three pediatric studies of Seqirus IIV3 (S-IIV3) or quadrivalent inactivated influenza vaccine (S-IIV4), prepared using the modified manufacturing process, with fever rates in three pediatric studies of historical (pre-2010) IIV3 formulations. The historical IIV3 formulations, S-IIV3, and S-IIV4 had 0/3, 2/3, and 4/4 vaccine strains split at 1.5% TDOC, respectively. METHODS: For each study, fever rates (any grade and severe) were determined for the following age subgroups (as applicable), using the fever intensity grading system used in the S-IIV3/S-IIV4 studies: 6 months to <3 years; 3 to <5 years; 5 to <9 years; and 9 to <18 years. RESULTS: For each age subgroup, the any grade and severe fever rates were lower in the S-IIV3/S-IIV4 studies than in the historical IIV3 formulation studies, with the greatest differences in fever rates observed in the youngest age groups. In the 6 months to <3 years group, the any grade fever rate was 7.0% (severe fever: 2.5%) in one S-IIV4 study compared with 38.7% to 40.0% (severe fever: 9.6% to 17.8%) in the historical IIV3 formulation studies. In the 3 to <5 years subgroup, the any grade fever rate was 4.9% (severe fever: 1.2%) in one S-IIV4 study compared with 34.1% to 36.0% (severe fever: 6.3% to 16.5%) in the historical IIV3 formulation studies. CONCLUSION: This analysis provides clinical evidence that the modified manufacturing process improved the fever profile across all pediatric age groups, in particular, in children aged <5 years.

Immunogenicity and safety of a quadrivalent inactivated influenza vaccine in children 6-59 months of age: A phase 3, randomized, noninferiority study.

BACKGROUND: In the Southern Hemisphere 2010 influenza season, Seqirus' split-virion, trivalent inactivated influenza vaccine was associated with increased reports of fevers and febrile reactions in young children. A staged clinical development program of a quadrivalent vaccine (Seqirus IIV4 [S-IIV4]; Afluria® Quadrivalent/Afluria Quad™/Afluria Tetra™), wherein each vaccine strain is split using a higher detergent concentration to reduce lipid content (considered the cause of the increased fevers and febrile reactions), is now complete. METHODS: Children aged 6-59 months were randomized 3:1 and stratified by age (6-35 months/36-59 months) to receive S-IIV4 (n = 1684) or a United States (US)-licensed comparator IIV4 (C-IIV4; Fluzone® Quadrivalent; n = 563) during the Northern Hemisphere 2016-2017 influenza season. The primary objective was to demonstrate noninferior immunogenicity of S-IIV4 versus C-IIV4. Immunogenicity was assessed by hemagglutination inhibition (baseline, 28 days postvaccination). Solicited, unsolicited, and serious adverse events were assessed for 7, 28, and 180 days postvaccination, respectively. RESULTS: S-IIV4 met the immunogenicity criteria for noninferiority. Adjusted geometric mean titer ratios (C-IIV4/S-IIV4) for the A/H1N1, A/H3N2, B/Yamagata, and B/Victoria strains were 0.79 (95% CI: 0.72, 0.88), 1.27 (1.15, 1.42), 1.12 (1.01, 1.24), and 0.97 (0.86, 1.09), respectively. Corresponding values for differences in seroconversion rates (C-IIV4 minus S-IIV4) were -10.3 (-15.4, -5.1), 2.6 (-2.5, 7.8), 3.1 (-2.1, 8.2), and 0.9 (-4.2, 6.1). Solicited, unsolicited, and serious adverse events were similar between vaccines in both age cohorts, apart from fever. Fever rates were lower with S-IIV4 (5.8%) than C-IIV4 (8.4%), with no febrile convulsions reported with either vaccine during the 7 days postvaccination. CONCLUSION: S-IIV4, manufactured with a higher detergent concentration, demonstrated noninferior immunogenicity to the US-licensed C-IIV4, with similar postvaccination safety and tolerability, in children aged 6-59 months. This completes the program demonstrating the immunogenicity and safety of S-IIV4 in participants aged 6 months and older. FUNDING: Seqirus Pty Ltd; ClinicalTrials.gov identifier:NCT02914275.

Immunogenicity and safety of a quadrivalent inactivated influenza virus vaccine compared with a comparator quadrivalent inactivated influenza vaccine in a pediatric population: A phase 3, randomized noninferiority study.

BACKGROUND: Seqirus 2010 Southern Hemisphere split-virion trivalent inactivated influenza vaccine (IIV3) was associated with increased febrile reactions in children. Studies in vitro concluded that increasing concentrations of splitting agent decreased residual lipids and attenuated proinflammatory cytokine signals associated with fever. We assessed immunogenicity and safety of a quadrivalent inactivated influenza vaccine (IIV4; produced using higher concentration of splitting agent) versus a United States-licensed comparator IIV4 in healthy children aged 5-17years. METHODS: Participants (N=2278) were randomized 3:1 and stratified by age (5-8years; 9-17years) to receive IIV4 (n=1709) or comparator IIV4 (n=569). Primary objective was to demonstrate noninferiority of IIV4 versus comparator IIV4 as assessed by hemagglutination inhibition (HI) geometric mean titer (GMT) ratio (upper bound of two-sided 95% confidence interval [CI]≤1.5) and difference in seroconversion rate (upper bound of two-sided 95% CI≤10%) for all four vaccine strains. HI antibody titers were assessed at baseline and 28days postvaccination. Solicited and unsolicited adverse events were assessed during each 7- and 28-day postvaccination period, respectively. RESULTS: IIV4 met immunogenicity criteria for noninferiority. Adjusted GMT ratios (comparator IIV4/IIV4) for A/H1N1, A/H3N2, B/Yamagata, and B/Victoria strains were 1.01 (95% CI; 0.93, 1.09), 1.05 (0.96, 1.15), 0.89 (0.81, 0.98), and 0.92 (0.83, 1.02), respectively. Corresponding values for differences (95% CI) in seroconversion rates (comparator IIV4 minus IIV4) were -3.1 (-8.0, 1.8), 0.4 (-4.5, 5.3), -3.4 (-8.3, 1.5), and -2.0 (-6.9, 2.9). Fever rates were numerically higher, but not statistically different, with IIV4 versus comparator IIV4. No new safety signals were reported. CONCLUSION: IIV4 demonstrated immunological noninferiority to the comparator IIV4 with a clinically acceptable safety profile in children aged 5-17years. Increased levels of virus splitting agent seem to have reduced fever rates observed in children with Seqirus IIV3, particularly those aged 5-8years. FUNDING: Seqirus Pty Ltd; Clinicaltrials.gov identifier: NCT02545543.

Immunogenicity and safety of a quadrivalent inactivated influenza vaccine compared with two trivalent inactivated influenza vaccines containing alternate B strains in adults: A phase 3, randomized noninferiority study.

BACKGROUND: Vaccination is the most effective means of influenza prevention. Efficacy of trivalent vaccines may be enhanced by including both B strain lineages. This phase 3, double-blind study assessed the immunogenicity and safety/tolerability of a quadrivalent inactivated influenza vaccine (IIV4) versus the United States (US)-licensed 2014-2015 trivalent inactivated influenza vaccine (IIV3-Yamagata [IIV3-YAM]; Afluria) and IIV3 containing the alternate Victoria B strain (IIV3-VIC) in adults ≥18years. METHODS: Participants (n=3484) were randomized 2:1:1 and stratified by age to receive IIV4 (n=1741), IIV3-YAM (n=871), or IIV3-VIC (n=872). The primary objective was to demonstrate noninferiority of the immunological response to IIV4 versus IIV3-YAM and IIV3-VIC. Noninferiority was assessed by hemagglutination inhibition geometric mean titer (GMT) ratio (IIV3/IIV4; upper bound of two-sided 95% confidence interval [CI]≤1.5) and seroconversion rate (SCR) difference (IIV3 - IIV4; upper bound of two-sided 95% CI≤10%) for vaccine strains. Solicited local and systemic adverse events (AEs) were assessed for 7days postvaccination, AEs recorded for 28days postvaccination, and serious AEs for 6months postvaccination. RESULTS: IIV4 elicited a noninferior immune response for matched strains, and superior response for unmatched B strains not contained in IIV3 comparators. Adjusted GMT ratios (95% CI) for A/H1N1, A/H3N2, B/YAM, and B/VIC strains were 0.93 (0.88, 0.99), 0.93 (0.88, 0.98), 0.87 (IIV3-YAM; 0.82, 0.93), and 0.95 (IIV3-VIC; 0.88, 1.03), respectively. Corresponding values for SCR differences (95% CI) were -1.1 (-4.5, 2.3), -1.7 (-5.0, 1.7), -3.2 (IIV3-YAM; -7.4, 0.9), and -1.6 (IIV3-VIC; -5.8, 2.5). AEs were generally mild and experienced by 52.9% of participants. Serious AEs were reported with a slightly higher frequency with IIV4 (2.3%) versus IIV3-YAM (1.6%) and IIV3-VIC (1.5%). CONCLUSIONS: IIV4 demonstrated immunological noninferiority to the US-licensed IIV3, and superiority for unmatched B strains not contained in IIV3 comparators. Safety/tolerability profiles were similar across vaccine groups. FUNDING: Seqirus; Clinicaltrials.gov: NCT02214225.

Randomized trial to compare the safety and immunogenicity of CSL Limited's 2009 trivalent inactivated influenza vaccine to an established vaccine in United States children.

A trivalent inactivated influenza vaccine (CSL's TIV, CSL Limited) was licensed under USA accelerated approval regulations for use in persons≥18 years. We performed a randomized, observer-blind study to assess the safety and immunogenicity of CSL's TIV versus an established US-licensed vaccine in a population≥6 months to <18 years of age. Subjects were stratified as follows: Cohort A (≥6 months to <3 years); Cohort B (≥3 years to <9 years); and Cohort C (≥9 years to <18 years). The subject's age and influenza vaccination history determined the dosing regimen (one or two vaccinations). Subjects received CSL's TIV (n=739) or the established vaccine (n=735) in the autumn of 2009. Serum hemagglutination-inhibition titers were determined pre-vaccination and 30 days after the last vaccination. No febrile seizures or other vaccine-related SAEs were reported. After the first vaccination for Cohorts A and B, respectively, the relative risks of fever were 2.73 and 2.32 times higher for CSL's TIV compared to the established vaccine. Irritability and loss of appetite (for Cohort A) and malaise (for Cohort B) were also significantly higher for CSL's TIV compared to the established vaccine. Post-vaccination geometric mean titers (GMTs) for CSL's TIV versus the established vaccine were 385.49 vs. 382.45 for H1N1; 669.13 vs. 705.61 for H3N2; and 100.65 vs. 93.72 for B. CSL's TIV demonstrated immunological non-inferiority to the established vaccine in all cohorts.

Malaria-specific transgenic CD4(+) T cells protect immunodeficient mice from lethal infection and demonstrate requirement for a protective threshold of antibody production for parasite clearance.

T cells are important in the immune response to malaria, both for their cytokines and their help for antibody production. To look at the relative importance of these roles, a T-cell receptor (TCR) transgenic mouse has been generated carrying a TCR specific for an epitope of the merozoite surface protein 1 (MSP-1) of the malaria parasite, Plasmodium chabaudi. In adoptive transfer experiments, malaria-specific CD4(+) T cells expand and produce interferon gamma (IFN-gamma) early in infection, but the population contracts quickly despite prolonged persistence of the parasite. MSP-1-specific CD4(+) cells can protect immunodeficient mice from lethal infection; however, the parasite is only completely cleared in the presence of B cells showing that T helper cells are critical. Levels of malaria-specific antibody and the speed of their production clearly correlate with the time of resolution of infection, indicating that a critical threshold of antibody production is required for parasite clearance. Furthermore, T cells specific for a shed portion of MSP-1 are able to provide help for antibody to the protective region, which remains bound to the infected erythrocyte, suggesting that MSP-1 has all of the components necessary for a good vaccine.

Dendritic cells, pro-inflammatory responses, and antigen presentation in a rodent malaria infection.

An infection of mice with Plasmodium chabaudi is characterized by a rapid and marked inflammatory response with a rapid but regulated production of interleukin-12 (IL-12), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma). Recent studies have shown that dendritic cells (DCs) are activated in vivo in the spleen, are able to process and present malaria antigens during infection, and may provide a source of cytokines that contribute to polarization of the CD4 T-cell response. P. chabaudi-infected erythrocytes are phagocytosed by DCs, and peptides of malaria proteins are presented on major histocompatibility complex (MHC) class II. The complex disulfide-bonded structure of some malaria proteins can impede their processing in DCs, which may affect the magnitude of the CD4 T-cell response and influence T-helper 1 (Th1) or Th2 polarization. DCs exhibit a wide range of responses to parasite-infected erythrocytes depending on their source, their maturational state, and the Plasmodium species or strain. P. chabaudi-infected erythrocytes stimulate an increase in the expression of costimulatory molecules and MHC class II on mouse bone marrow-derived DCs, and they are able to induce the production of pro-inflammatory cytokines such as IL-12, TNF-alpha, and IL-6, thus enhancing the Th1 response of naïve T cells. IFN-gamma and TNF-alpha play a role in both protective immunity and the pathology of the infection, and the inflammatory disease may be regulated by IL-10 and transforming growth factor-beta. It will therefore be important to elucidate the host and parasite molecules that are involved in activation or suppression of the DCs and to understand the interplay between these opposing forces on the host response in vivo during a malaria infection.