Clinical Development Strategies and Considerations for Zika Vaccine Licensure.

The Zika outbreak that began in 2015 has spread from Brazil to countries across the Western Hemisphere including the United States, presenting global public health challenges that call for the expedited development and availability of preventive vaccines to protect against Zika virus disease. While the general principles guiding the nonclinical and clinical development for Zika vaccines are the same as those of other preventive vaccines, unique considerations apply, in particular if development occurs during a public health emergency. Furthermore, incomplete information about the pathogenesis of Zika virus disease and the mechanism by which candidate preventive vaccines potentially may confer protection presents additional challenges to their clinical development. Nevertheless, definition of clinical development strategies to enable sound regulatory assessment, with a goal toward licensure is critical for these products. This article will provide an overview of the regulatory considerations for the clinical development and licensure of Zika vaccine candidates including a discussion of clinical study designs, approaches to demonstrate vaccine effectiveness, and regulatory pathways to licensure.

Clinical evaluation of pertussis vaccines: US Food and Drug Administration regulatory considerations.

The resurgence of pertussis in the United States has stimulated considerable public health interest in developing new vaccination strategies to improve control of pertussis. The purpose of this article is to review the US Food and Drug Administration's regulatory framework for the prelicensure clinical evaluation of preventive vaccines and the clinical approaches that have been used to demonstrate effectiveness of US-licensed vaccines containing an acellular pertussis component.

Non-animal replacement methods for human vaccine potency testing: state of the science and future directions.

NICEATM and ICCVAM convened an international workshop to review the state of the science of human and veterinary vaccine potency and safety testing methods, and to identify opportunities to advance new and improved methods that can further reduce, refine, and replace animal use. This report addresses methods and strategies identified by workshop participants for replacement of animals used for potency testing of human vaccines. Vaccines considered to have the highest priority for future efforts were (1) vaccines for which antigen quantification methods are already developed but not validated, (2) vaccines/components that require the largest number of animals, (3) vaccines that require an in vivo challenge test, and (4) vaccines with in vivo tests that are highly variable and cause a significant number of invalid tests. Vaccine potency tests identified as the highest priorities for replacement were those for diphtheria and tetanus, pertussis (whole cell and acellular), rabies, anthrax, polio vaccine (inactivated) and complex combination vaccines based on DT or DTwP/aP. Research into understanding the precise mechanism of protection afforded by vaccines and the identification of clinically relevant immunological markers are needed to facilitate the successful implementation of in vitro testing alternatives. This report also identifies several priority human vaccines and associated research objectives that are necessary to successfully implement in vitro vaccine potency testing alternatives.