Table 2.

2016 updated viability factors from Milstien et al. [1]. Changes in bold denote added factor or sub-element.

Viability factor	2016
Economies of scale and volume; product portfolio	•Number of vaccines manufactured >2 •Depending on the technology – production volumes on par with global average
cGMP and consistency of production	•Percentage of lots failed <5% •Consistent number of lots per year •Consistent number of doses per lot •Maintenance program and budget •Planned, significant capital expenditure per year •Quality assurance budget and program •WHO-prequalified product(s) or plan to reach prequalificationb
Functioning NRA—assurance of quality	•Customer has choice • NRA with six functionsa: 1. Published set of requirements for licensing 2. Surveillance of vaccine field performance 3. System of lot release 4. Use of laboratory when needed 5. Regular inspections for cGMP 6. Evaluation of clinical performance •NRA is an independent authority
Systems to access new technologies and support research and development	•Process development budget and program •Research budget and program •Realistic plan to meet defined market needs (national, international, or combination) •Added new technology in last five years or joint ventures, collaborations, or other technology transfers in last five years •Able to access and license intellectual property
Historical performance	•Supply sufficient to meet target market demand •Proven scale-up in last five years
Government policies and enabling environment for investment and regulation	•Government supporting WHO recognition of NRA •Government incentives for production of vaccines •Government supports partnerships with international research organizations and manufacturers
Management structure	•Detailed three-year strategic plan •Human resources training plan (critical for cGMP and prequalification) •Appropriate ratio of skilled/unskilled staff •Ability to access capital sources
Legal status/autonomy	•Control to set salaries •Control to hire and fire as necessary •Control over revenues, budgets •Price covers full cost per dose •Political stability

cGMP: current Good Manufacturing Practice; NRA: national regulatory authority (formerly national control authority); WHO: World Health Organization.

^aSee the WHO immunization standards website for more detail: http://www.who.int/immunization_standards/national_regulatory_authorities/role/en/.

^bWHO prequalification will be necessary for manufacturers requiring access to international markets to achieve economies of scale; however, some manufacturers, operating in very large markets, with protections against competition, may be able to reach scale in which WHO prequalification is not necessary.