Vaccines for emerging pathogens: prospects for licensure

Abstract

Summary Globally, there are a number of emerging pathogens. For most, there are no licensed vaccines available for human use, although there is ongoing research and development. However, given the extensive and increasing list of emerging pathogens and the investment required to bring vaccines into clinical use, the task is huge. Overlaid on this task is the risk of anti‐microbial resistance (AMR) acquisition by micro‐organisms which can endow a relatively harmless organism with pathogenic potential. Furthermore, climate change also introduces a challenge by causing some of the insect vectors and environmental conditions prevalent in tropical regions to begin to spread out from these traditional areas, thus increasing the risk of migration of zoonotic disease. Vaccination provides a defence against these emerging pathogens. However, vaccines for pathogens which cause severe, but occasional, disease outbreaks in endemic pockets have suffered from a lack of commercial incentive for development to a clinical standard, encompassing Phase III clinical trials for efficacy. An alternative is to develop such vaccines to request US Emergency Use Authorization (EUA), or equivalent status in the United States, Canada and the European Union, making use of a considerable number of regulatory mechanisms that are available prior to licensing. This review covers the status of vaccine development for some of the emerging pathogens, the hurdles that need to be overcome to achieve EUA or an equivalent regional or national status and how these considerations may impact vaccine development for the future, such that a more comprehensive stockpile of promising vaccines can be achieved.

Anti‐tick and pathogen transmission blocking vaccines

“…In addition, depending on the formulations, conversations with the EPA (Environmental Protection Agency) are advised to ensure the correct regulatory channels are followed. 123,124 In order to obtain licensure, substantial data on efficacy shown using challenge models where vaccine efficacy is equated to relative reduction in risk of death/ infection are required. Group numbers will need to be sufficient to calculate the prevented fraction, or vaccine efficacy, showing there is a significant reduction of infection/ death in the target animal upon vaccination.…”

“…[125][126][127] In addition, field trials demonstrating safety in at least one suitable animal model need to be performed. 123 To ensure successful licensing and marketing of a wildlife vaccine, clear demonstration of not only efficacy and safety, but also purity and batch consistency is required. 124,128…”

“…In the US, a wildlife vaccine is likely to be regulated by the USDA‐CVB (Center for Veterinary Biologics), whereas vaccines targeted towards livestock could be regulated either by the USDA‐CVB or the FDA. In addition, depending on the formulations, conversations with the EPA (Environmental Protection Agency) are advised to ensure the correct regulatory channels are followed 123,124 . In order to obtain licensure, substantial data on efficacy shown using challenge models where vaccine efficacy is equated to relative reduction in risk of death/ infection are required.…”

Editorial: Molecular Vaccines Against Pathogens in the Post-genomic Era

“…The development and implementation of vaccines are one of the greatest Public Health achievements in human history (Centers-for- Disease-Control-and-Prevention, 2011a,b). In the first decade of the twenty-first century, the Expanded Program on Immunizations averts more than 2.5 million deaths every year (WHO, 2009). Vaccines not only prevent deaths, disease, and disability but also provide community protection by reducing the spread of the disease within a population (Orenstein and Ahmed, 2017).…”

Vaccines for emerging pathogens: from research to the clinic. Part two

“…Worldwide, attention is now turning to the task of vaccines for these emerging and re‐emerging pathogens, with renewed interest and support from international governments, the WHO and organisations such as the Coalition for Epidemic Preparedness Innovations (CEPI), the Global Alliance for Vaccines and Immunisation (GAVI) and philanthropic organisations such as the Gates Foundation. The final review in this series, by Williamson and Westlake , considers the prospects for actually bringing some of the candidate vaccines being developed for the emerging pathogens to licensure. Illustrated with examples of candidate vaccines, it weighs up the likelihood of achieving regulatory approval for some of these candidates.…”