The development of new TB vaccines is a priority for WHO as it is an important unmet medical need. To support this effort, WHO’s Product Development for Vaccines Advisory Committee (PDVAC) called for the development of a WHO preferred Product Characteristics (PPC) for new TB vaccines. PPCs describe WHO preferences for parameters of vaccines, in particular their indications, target groups, possible immunization strategies, and features of desired clinical data related to safety and efficacy, supportive of policy decision making. The primary target audience for the PPC is any entity intending to eventually seek WHO policy recommendations and prequalification for their products, which is required for procurement by UN agencies. Vaccine PPCs are built through a wide consensus building process and result from interactions with a variety of stakeholders.

More on WHO Preferred Product Characteristics (PPCs)

The TB vaccine candidate pipeline includes various vaccine platforms including whole cell vaccines, adjuvanted proteins, and recombinant subunit vector vaccines. Candidate vaccines are being developed for prevention of TB disease in adolescents and adults, for early life immunization as BCG replacement, as BCG boosters, for vaccination of TB patients after treatment to prevent disease recurrence, or as immunotherapeutic adjuncts to drug therapy intended to reduce treatment duration. Up to recently, there was no coherently communicated consensus as to the preferred product characteristics (PPC) that would adequately support favorable policy recommendations for implementation where needed.

A WHO PPC document for new tuberculosis vaccines was first develop to cover the priority need for vaccines that protect against pulmonary TB in adults, and new TB vaccines with better safety and efficacy characteristic than BCG to administer to neonates and infants.

WHO PPCs for new tuberculosis vaccines

A WHO PPC document for tuberculosis vaccines for improvement of treatment outcome was also developed, more recently. Treating TB requires a multidrug course of treatment lasting 6 months, or longer for drug-resistant TB. Treatment failure and recurrence after end-of-treatment can have devastating consequences, and may be associated with the development of drug-resistant TB. Vaccines have the potential to serve as immunotherapeutic adjuncts to antibiotic treatment regimens for TB. A therapeutic vaccine for TB patients, administered towards completion of a prescribed course of drug therapy or at certain time(s) during treatment, could improve outcomes through immune-mediated control and clearance of bacteria and prevention of re-infection, and provide on the long-term options to simplify and shorten drug treatment regimen.

WHO Preferred Product Characteristics for Therapeutic Vaccines to Improve Tuberculosis Treatment Outcomes