Pharmacotherapeutic group: Influenza vaccine, ATC code: J07BB02
Mechanism of action
Cell-based Trivalent Influenza Vaccine Seqirus provides active immunisation against the influenza virus strains contained in the vaccine. It induces humoral antibodies against the haemagglutinins. These antibodies neutralise influenza viruses.
Specific levels of haemagglutination inhibition (HI) antibody titres post-vaccination with inactivated influenza vaccine have not been correlated with protection from influenza virus. In some human studies, antibody titres of 1:40 or greater have been associated with protection from influenza illness in up to 50% of subjects.
Antibody against one influenza virus type or subtype confers limited or no protection against another. Furthermore, antibody to one antigenic variant of influenza virus might not protect against a new antigenic variant of the same type or subtype.
Annual revaccination with current influenza vaccines is recommended because immunity declines during the year after vaccination and circulating strains of influenza virus may change from year to year.
Pharmacodynamic effects
Data for Cell-based Quadrivalent Influenza Vaccine Seqirus are relevant to Cell-based Trivalent Influenza Vaccine Seqirus because both vaccines are manufactured using the same process and have overlapping compositions.
Adult population
Clinical efficacy of cell-based trivalent influenza vaccine (TIVc) against culture-confirmed influenza in adults
A multinational, randomised, observer-blinded, placebo-controlled trial (V58P13) was performed to assess clinical efficacy and safety of TIVc during the 2007-2008 influenza season in adults aged 18 to less than 50 years. A total of 11,404 subjects were enrolled to receive TIVc (N = 3 828), an egg-based comparator vaccine (N = 3 676) or placebo (N = 3 900) in a 1:1:1 ratio.
TIVc efficacy was defined as the prevention of culture-confirmed symptomatic influenza illness caused by viruses antigenically matched to those in the vaccine compared to placebo. Influenza cases were identified by active and passive surveillance of influenza-like illness (ILI). ILI was defined according to Centers for Disease Control and Prevention (CDC) case definition, i.e., a fever (oral temperature ≥100.0°F / 38°C) and cough or sore throat. After an episode of ILI, nose and throat swab samples were collected for analysis. Vaccine efficacies against vaccine-matched influenza viral strains, against all influenza viral strains, and against individual influenza viral subtypes were calculated (Table 3).
Table 3: Comparative efficacy of TIVc versus placebo against culture-confirmed influenza by influenza viral subtype (V58P13)
| | TIVc (N = 3776) | Placebo (N = 3843) | Vaccine Efficacy* |
| | Attack Rate (%) | Number of Subjects with Influenza | Attack Rate (%) | Number of Subjects with Influenza | % | Lower Limit of One-Sided 97.5% CI |
| Antigenically Matched Strains |
| Overall | 0.19 | 7 | 1.14 | 44 | 83.8 | 61.0 |
| Individual strains | A/H3N2** | 0.05 | 2 | 0 | 0 | -- | -- |
| A/H1N1 | 0.13 | 5 | 1.12 | 43 | 88.2 | 67.4 |
| B** | 0 | 0 | 0.03 | 1 | -- | -- |
| All Culture-Confirmed Influenza |
| Overall | 1.11 | 42 | 3.64 | 140 | 69.5 | 55.0 |
| Individual strains | A/H3N2 | 0.16 | 6 | 0.65 | 25 | 75.6 | 35.1 |
| A/H1N1 | 0.16 | 6 | 1.48 | 57 | 89.3 | 73.0 |
| B | 0.79 | 30 | 1.59 | 61 | 49.9 | 18.2 |
* Simultaneous one-sided 97.5% confidence intervals for the vaccine efficacy of each influenza vaccine relative to placebo based on the Sidak-corrected score confidence intervals for the two relative risks.
Vaccine Efficacy = (1 - Relative Risk) x 100%;
** There were too few cases of influenza due to vaccine-matched influenza A/H3N2 or B to adequately assess vaccine efficacy.
Immunogenicity of Cell-based Quadrivalent and Trivalent Influenza Vaccines Seqirus in adults
In a randomised, double‑blind, controlled study (V130_01), adult subjects received Cell-based Quadrivalent Influenza Vaccine Seqirus (N = 1 334) or one of two trivalent formulations (TIVc) [TIV1c (N = 677) or TIV2c (N = 669)]. The immune response to each of the vaccine antigens was assessed, 21 days after vaccination. The immunogenicity endpoints were geometric mean antibody titres (GMTs) of haemagglutination inhibition (HI) antibodies response and percentage of subjects who achieved seroconversions, defined as a pre-vaccination HI titre of <1:10 with a post vaccination titre ≥1:40 or with a pre-vaccination HI titre of ≥10 and a minimum 4-fold increase in serum HI antibody titre.
Cell-based Quadrivalent Influenza Vaccine Seqirus was shown to be non-inferior to TIVc, including in age subgroup analyses (subjects 18 to less than 65 years of age and 65 years of age and above) (see Table 4).
Table 4: Immunogenicity of Cell-based Quadrivalent and Trivalent Influenza Vaccines Seqirus in adults 18 years of age and above – Per protocol analysis set (V130_01)
| | | Cell-based Quadrivalent Influenza Vaccine Seqirus suspension N = 1250 | TIV1c/TIV2ca N = 635/N = 639 | Vaccine Group Ratio (95% CI) | Vaccine Group Difference (95% CI) |
| A/H1N1 | GMT (95% CI) | 302.8 (281.8-325.5) | 298.9 (270.3-330.5) | 1.0 (0.9-1.1) | - |
| Seroconversion Rateb (95% CI) | 49.2% (46.4-52.0) | 48.7% (44.7-52.6) | - | -0.5% (-5.3-4.2) |
| A/H3N2 | GMT (95% CI) | 372.3 (349.2-396.9) | 378.4 (345.1-414.8) | 1.0 (0.9-1.1) | - |
| Seroconversion Rateb (95% CI) | 38.3% (35.6-41.1) | 35.6% (31.9-39.5) | - | -2.7% (-7.2-1.9) |
| B1 | GMT (95% CI) | 133.2 (125.3-141.7) | 115.6 (106.4-125.6) | 0.9 (0.8-1.0) | - |
| Seroconversion Rateb (95% CI) | 36.6% (33.9-39.3) | 34.8% (31.1-38.7) | - | -1.8% (-6.2-2.8) |
| B2 | GMT (95% CI) | 177.2 (167.6-187.5) | 164.0 (151.4-177.7) | 0.9 (0.9-1.0) | - |
| Seroconversion Rateb (95% CI) | 39.8% (37.0-42.5) | 35.4% (31.7-39.2) | - | -4.4% (-8.9-0.2) |
Abbreviations: GMT = geometric mean titre; CI = confidence interval.
a The comparator vaccine for noninferiority comparisons for A/H1N1, A/H3N2 and B1 is TIV1c, for B2 it is TIV2c.
b Seroconversion rate = percentage of subjects with either a pre-vaccination HI titre <1:10 and post-vaccination HI titre ≥1:40 or with a pre-vaccination HI titre ≥1:10 and a minimum 4-fold increase in post-vaccination HI antibody titre.
Bold = Non-inferiority criterion met.
Paediatric population
Clinical efficacy of Cell-based Quadrivalent Influenza Vaccine Seqirus in the paediatric population 6 months to less than 18 years of age
Absolute efficacy of Cell-based Quadrivalent Influenza Vaccine Seqirus was evaluated in children 2 years to less than 18 years of age in Study V130_12 and in children 6 months to less than 48 months, in Study V130_14.
Study V130_12 was a multinational, randomised, non-influenza vaccine comparator-controlled efficacy study conducted in 8 countries over 3 influenza seasons, in which 4 514 subjects were enrolled to received 0.5 ml of Cell-based Quadrivalent Influenza Vaccine Seqirus or a non-influenza comparator in a 1:1 ratio. Based on influenza vaccination history, participants received one or two doses (28 days apart) of the study vaccine.
Vaccine efficacy was assessed by the prevention of confirmed influenza illness caused by any influenza Type A or B strain. Influenza cases were identified by active surveillance of influenza-like illness (ILI) and confirmed by viral culture and/or real-time polymerase chain reaction (RT-PCR). An ILI episode was defined as a fever body temperature ≥ 37.8°C) along with at least one of the following: cough, sore throat, nasal congestion, or rhinorrhoea. Vaccine efficacy against laboratory confirmed influenza was calculated (Table 5).
Table 5: Absolute vaccine efficacy (95% CI) in subjects 2 years to less than 18 years of age – FAS Efficacy1 (Study V130_12)
| | Number of subjects per protocol1 | Number of cases of influenza | Attack Rate (%) | Vaccine Efficacy (VE) |
| % | 95% CI of VE |
| RT-PCR or Culture Confirmed Influenza |
| Cell-based Quadrivalent Influenza Vaccine Seqirus | 2257 | 175 | 7.8 | 54.63 | 45.67, 62.12 |
| Non-Influenza Comparator | 2252 | 364 | 16.2 | - | - |
| Culture Confirmed Influenza |
| Cell-based Quadrivalent Influenza Vaccine Seqirus | 2257 | 115 | 5.1 | 60.81 | 51.30, 68.46 |
| Non-Influenza Comparator | 2252 | 279 | 12.4 | - | - |
| Antigenically Matched Culture-Confirmed Influenza |
| Cell-based Quadrivalent Influenza Vaccine Seqirus | 2257 | 90 | 4.0 | 63.64 | 53.64, 71.48 |
| Non-Influenza Comparator | 2252 | 236 | 10.5 | - | - |
| 1Number of subjects in the Full-Analysis Set (FAS)– Efficacy, which included all subjects randomised, received a study vaccination and provided efficacy data. |
In Study V130_14, absolute efficacy of Cell-based Quadrivalent Influenza Vaccine Seqirus was evaluated in children 6 months to less than 48 months of age. This was a multicentre, randomised, observer-blind, non-influenza vaccine comparator-controlled efficacy study conducted in 15 countries over 5 influenza seasons. In the study, 5 697 subjects received either Cell-based Quadrivalent Influenza Vaccine Seqirus (N=2 857) or a non-influenza vaccine comparator (N=2 840) in a 1:1 ratio. The full analysis set (FAS) for efficacy consisted of 5691 subjects. Based on influenza vaccination history, participants received one or two doses (28 days apart) of the study vaccine.
Vaccine efficacy was assessed by the prevention of confirmed influenza illness caused by any influenza Type A or B strain. Influenza cases were identified by active surveillance of influenza-like illness (ILI) and confirmed by real-time polymerase chain reaction (RT‑PCR) and viral culture. An ILI episode was defined as a fever body temperature ≥ 37.8°C with at least one of the following on the same day: cough, sore throat, nasal congestion, rhinorrhoea, earache or ear discharge. Vaccine efficacy against laboratory confirmed influenza was calculated (Table 6).
Table 6: Absolute vaccine efficacy (95% CI) in subjects 6 months to less than 4 years of age – FAS Efficacy1 (Study V130_14)
| | Number of subjects per protocol | Number of cases of influenza | Attack rate (%) | Vaccine efficacy (VE) |
| % | Lower Limit of Two Sided CI of VE |
| RT-PCR confirmed influenza2, 3 |
| Cell-based quadrivalent influenza vaccine Seqirus | 2856 | 104 | 3.64 | 41.26 | 21.554 |
| Non-Influenza comparator | 2835 | 173 | 6.10 | - | - |
| Culture-confirmed influenza5 |
| Cell-based quadrivalent influenza vaccine Seqirus | 2856 | 61 | 2.14 | 50.67 | 32.83 |
| Non-Influenza comparator | 2835 | 121 | 4.27 | - | - |
| Antigenically matched culture-confirmed influenza2 |
| Cell-based quadrivalent influenza vaccine Seqirus | 2856 | 44 | 1.54 | 46.90 | 19.196 |
| Non-Influenza Comparator | 2835 | 82 | 2.89 | - | - |
| 1 Number of subjects in the Full-Analysis Set (FAS) – Efficacy, which included all subjects randomised, received a study vaccination and provided efficacy data 2 Primary endpoint of study 3 The number of subjects with first occurrence of moderate-to-severe RT-PCR confirmed influenza was 9 in the comparator group and 0 in the cell-based quadrivalent influenza vaccine group. 4 The pre-defined success criterion was defined as the lower limit of the two-sided 97.98% CI of absolute vaccine efficacy was above 0% 5 Culture confirmed influenza due to any influenza Type A and/or Type B virus regardless of antigenic match to the influenza strains in the vaccine (two-sided 95% CI) 6 The pre-defined success criterion was defined as the lower limit of the two-sided 97.5% CI of absolute vaccine efficacy was above 0% |
Immunogenicity of Cell-based Quadrivalent Influenza Vaccine Seqirus in children 6 months to less than 4 years of age
In a randomised, observer-blind, multicentre study (Study V130_10), 1597 subjects received Cell-based Quadrivalent Influenza Vaccine Seqirus and 805 subjects received a comparator quadrivalent influenza vaccine. The immune response to each of the vaccine antigens was assessed, 28 days after last vaccination. The immunogenicity endpoints were geometric mean antibody titres (GMTs) and percentage of subjects who achieved seroconversion, defined as a pre-vaccination HI or MN titre of <1:10 with a post-vaccination titre ≥1:40 or with a pre-vaccination HI or MN titre ≥ 1:10 and a minimum 4‑fold increase in serum antibody titre. GMTs and seroconversion rates were measured by haemagglutination inhibition (HI) assay for A/H1N1, B/Yamagata and B/Victoria strains and by microneutralization (MN) assay for the A/H3N2 strain.
Cell-based Quadrivalent Influenza Vaccine Seqirus was noninferior to the comparator QIV for all 4 influenza strains (see Table 7).
Table 7: Noninferiority of Cell-based Quadrivalent Influenza Vaccine Seqirus relative to comparator QIV in children 6 months to less than 4 years of age – Per-Protocol Analysis Set (V130_10)
| | | Cell-based Quadrivalent Influenza Vaccine Seqirus | Comparator QIV | Vaccine Group Ratio | Vaccine Group Difference |
| A/H1N1 | | N = 1092 | N =575 | | |
| GMT (95% CI) | 78.0 (70.8, 86.0) | 57.3 (50.8, 64.6) | 0.73 (0.65, 0.84) | - |
| Seroconversion Rate a (95% CI) | 58.2% (55.3, 61.2) | 46.8% (42.6, 51.0) | - | -11.5 (-16.5, -6.4) |
| A/H3N2 | | N = 1078 | N = 572 | | |
| GMT (95% CI) | 23.1 (21.2, 25.1) | 23.9 (21.6, 26.6) | 1.04 (0.93, 1.16) | - |
| Seroconversion Rate a (95% CI) | 27.6% (25.0, 30.4) | 30.8% (27.0, 34.7) | - | 3.1 (-1.4, 7.8) |
| B/Yamagata | | N = 1092 | N = 575 | | |
| GMT (95% CI) | 35.6 (32.9, 38.6) | 26.0 (23.5, 28.6) | 0.73 (0.66, 0.81) | - |
| Seroconversion Rate a (95% CI) | 46.5% (43.5, 49.5) | 31.7% (27.9, 35.6) | - | -14.9 (-19.6, -10.0) |
| B/Victoria | | N = 1092 | N = 575 | | |
| GMT (95% CI) | 22.4 (20.7, 24.2) | 19.6 (17.8, 21.6) | 0.88 (0.79, 0.97) | - |
| Seroconversion Rate a (95% CI) | 30.3% (27.6, 33.1) | 24.4% (20.9, 28.1) | - | -6.0 (-10.3, -1.4) |
Abbreviations: GMT = Geometric Mean Titre. CI = Confidence Interval.
a Seroconversion rate = percentage of subjects with either a pre-vaccination titre < 1:10 and post-vaccination titre ≥ 1:40 or with a pre-vaccination titre ≥ 1:10 and a minimum 4-fold increase in post-vaccination antibody titre
Bold = Non-inferiority criterion met