Safety of AS03-adjuvanted influenza vaccines: A review of the evidence.

Clinical and post-licensure data have demonstrated that AS03-adjuvanted inactivated split virion vaccines, many with reduced antigen content, are effective against influenza infection. The objective of this review is to provide a comprehensive assessment of the safety of trivalent seasonal, monovalent pre-pandemic and pandemic AS03-adjuvanted influenza vaccines, based on non-clinical, clinical and post-licensure data in various populations. Non-clinical studies on local tolerance, toxicology and safety pharmacology did not raise any safety concerns with AS03 administered alone or combined with various influenza antigens. Data from clinical trials with over 55,000 vaccinated subjects showed that AS03-adjuvanted influenza vaccines were generally well tolerated and displayed an acceptable safety profile, although the power to detect rare events was limited. Approximately 90 million doses of A/H1N1pdm09 pandemic influenza vaccines (Pandemrix and Arepanrix H1N1) were administered worldwide, which contributed post-licensure data to the collective safety data for AS03-adjuvanted influenza vaccines. An association between Pandemrix and narcolepsy was observed during the A/H1N1pdm09 pandemic, for which a role of a CD4 T cell mimicry sequence in the haemagglutinin protein of A/H1N1pdm09 cannot be excluded. Provided that future AS03-adjuvanted influenza vaccines do not contain this putative mimicry sequence, this extensive safety experience supports the further development and use of AS03-adjuvanted inactivated split virion candidate vaccines against seasonal and pandemic influenza infections.

Vaccine safety evaluation: Practical aspects in assessing benefits and risks.

Vaccines are different from most medicines in that they are administered to large and mostly healthy populations including infants and children, so there is a low tolerance for potential risks or side-effects. In addition, the long-term benefits of immunisation in reducing or eliminating infectious diseases may induce complacency due to the absence of cases. However, as demonstrated in recent measles outbreaks in Europe and United States, reappearance of the disease occurs as soon as vaccine coverage falls. Unfounded vaccine scares such as those associating the combined measles-mumps-rubella vaccine with autism, and whole-cell pertussis vaccines with encephalopathy, can also have massive impacts, resulting in reduced vaccine uptake and disease resurgence. The safety assessment of vaccines is exhaustive and continuous; beginning with non-clinical evaluation of their individual components in terms of purity, stability and sterility, continuing throughout the clinical development phase and entire duration of use of the vaccine; including post-approval. The breadth and depth of safety assessments conducted at multiple levels by a range of independent organizations increases confidence in the rigour with which any potential risks or side-effects are investigated and managed. Industry, regulatory agencies, academia, the medical community and the general public all play a role in monitoring vaccine safety. Within these stakeholder groups, the healthcare professional and vaccine provider have key roles in the prevention, identification, investigation and management of adverse events following immunisation (AEFI). Guidelines and algorithms aid in determining whether AEFI may have been caused by the vaccine, or whether it is coincidental to it. Healthcare providers are encouraged to rigorously investigate AEFIs and to report them via local reporting processes. The ultimate objective for all parties is to ensure vaccines have a favourable benefit-risk profile.

Safety, immunogenicity, and antibody persistence following an investigational Streptococcus pneumoniae and Haemophilus influenzae triple-protein vaccine in a phase 1 randomized controlled study in healthy adults.

We investigated a protein-based nontypeable Haemophilus influenzae (NTHi) and pneumococcal (HiP) vaccine containing pneumococcal histidine triad D (PhtD), detoxified pneumolysin (dPly), and NTHi protein D (PD) in adults. In a phase I study, 40 healthy 18- to 40-year-old subjects were randomized (2:2:1) to receive two HiP doses administered 60 days apart, with or without AS03 adjuvant (HiP-AS and HiP groups, respectively), or Engerix B (GlaxoSmithKline, Belgium) as a control. Safety, antibodies, and antigen-specific CD4(+) T-cell immune responses were assessed before and until 480 days after vaccination. No serious adverse events were reported, and no subject withdrew due to an adverse event. Local and systemic symptoms were reported more frequently in the HiP-AS group than in the other two groups. The frequency and intensity of local and systemic symptoms appeared to increase after the second dose of HiP-AS or HiP but not Engerix B. Antibody geometric mean concentrations (GMCs) for PhtD, dPly, and PD increased after each dose of HiP-AS or HiP, with higher GMCs being observed in the HiP-AS group (statistically significant for anti-PD after dose 1 and anti-Ply after dose 2). GMCs remained higher at day 420 than prior to vaccination in both the HiP-AS and HiP groups. Antigen-specific CD4(+) T cells increased after each dose but were unmeasurable by day 480. Two doses of an investigational PhtD-dPly-PD protein vaccine induced humoral immunity and antigen-specific CD4(+) T-cell responses after each dose, with generally higher responses when the vaccine was administered with AS03. HiP combined with AS03 appeared to be more reactogenic than the antigens alone. (This study has been registered at ClinicalTrials.gov under registration no. NCT00814489.).