Indication
Prevention of severe influenza illness. Policy-makers from LMICs are expected to place higher value on vaccines indicated for prevention of severe illness than prevention of ambulatory illness.
Intended use
By 2022, greater protection against vaccine-matched or drifted influenza strains than provided by currently prequalified non-adjuvanted nonreplicating influenza vaccines, and protection against severe influenza for at least one year, will have been demonstrated for seasonal influenza vaccines that are suitable for high-risk groups in low and middle income countries.
Target population
Children aged 6 weeks through 59 months. Children were prioritized given their high influenza illness burden and existing immunization services in LMICs. The lower end of the age range was chosen to coincide with the first contact within routine childhood immunization schedules and is consistent with the duration of protection demonstrated from
maternal influenza vaccination clinical trials. The upper end of the age range can feasibly be served within existing paediatric immunization services.
Use setting
Dosage, regimen, and cost of goods should be compatible with affordable supply. The vaccine should be cost-effective and price should not be a barrier to access, including in LMICs.
Performance
Correlates of protection of influenza vaccines against severe influenza illness are needed to minimize costs of trials and to promote innovation. The product should be prequalified according to standard procedures for assessing the acceptability of vaccines for purchase by United Nations agencies.20 The WHO defined criteria for programmatic suitability of vaccines should be met.20 Dosage, regimen, and cost of goods should be compatible with affordable supply. The vaccine should be cost-effective and price should not be a barrier to access, including in LMICs. There is a relative correlate of protection for HA-based vaccines against laboratory-confirmed influenza illness, but no established correlate of protection for severe influenza outcomes. There is no correlate of protection against severe laboratory-confirmed influenza illness for either HA or non-HA based influenza vaccines. There is no correlate of protection for non-HA based influenza vaccines or live attenuated influenza vaccines against laboratory-confirmed influenza illness of any type.
Efficacy
Severe laboratory-confirmed influenza illness is the preferred outcome measure for efficacy studies. One or both of the following advancements in influenza vaccine performance are preferred for demonstration of vaccine efficacy:
1) The vaccine efficacy should be better than that of currently prequalified non-replicating non-adjuvanted seasonal influenza vaccines for the specific age group for vaccine-matched strains against the recommended outcome measure.
OR
2) The vaccine efficacy should be better than that of currently prequalified non-replicating non-adjuvanted seasonal influenza vaccines for the specific age group for circulating antigenically drifted strains against the recommended outcome measure.
Safety
Vaccine risk-benefit assessment should favour vaccine use to prevent severe influenza illness. An increase in mild reactogenicity may be acceptable if the vaccine prevents severe disease. Severe reactogenicity should occur at a rate similar to or less than that associated with currently prequalified non-replicating, nonadjuvanted seasonal influenza vaccines. The preferred vaccine safety profile depends on the burden and severity of the disease being prevented.
