Dear Colleagues,

Zika virus was identified in the late 1940s and was a sporadic and infrequent cause of human disease until 2007 when a large clinical outbreak occurred on Yap Island. A similar event with a significant clinical attack rate occurred shortly thereafter in French Polynesia (2013). It was not until the Zika virus reached the Americas in ~2014/15 where its potential for devastating adverse neurologic and congenital outcomes was realized. The cluster of Zika virus infections in pregnant women in Brazil and adverse fetal outcomes ranging from intra-uterine death to developmental delays called the world to action to investigate the outbreak, expand our understanding of the virus, and to race to develop medical countermeasures in the form of drugs and vaccines.

The race for a Zika vaccine incorporated numerous entities to include biotech, big pharma, government, the military, non-governmental organizations, and academia. Great strides were made very quickly in the development of animal models of infection and disease, animal models of maternal-fetal infection and outcome, explorations of immunoprotective and immunopathogenic profiles, development of analytic assays, and construction of vaccine prototypes. Regulators worked closely with vaccine developers and the bioethics community to ensure volunteer vaccine recipient safety while not delaying development of vaccine candidate which may have potential for clinical benefit. Numerous phase I human studies of multiple different Zika vaccine prototypes were initiated and two candidates advanced to small scale phase II studies. It is appropriate at this time to take an inventory of progress in the development of a Zika vaccine and the questions and tasks which remain to make wide spread availability of a safe and effective product a reality.

In this Special Issue we will provide a state-of-the-art review of the Zika vaccine development field from a number of different perspectives to include; (1) epidemiology and pathophysiology of disease (Has the target population for a vaccine changed?); (2) pre-clinical development (What animal models have emerged as the most informative to support vaccine development and why and what is a brief summary of the most promising vaccine constructs in pre-clinical development?); (3) biomanufacturing (Are there unique challenges to producing Zika vaccines based on the constructs currently being tested in clinical trials); (4) clinical development (What are the unique aspects of a Zika vaccine clinical development plan in the context of the projected Target Product Profile and what is a brief summary of the constructs in clinical development?); (5) regulatory strategy (What are the most likely pathways to licensure based on the current understanding of Zika epidemiology and the possibility a traditional clinical endpoint study may not be possible?); and (6) implementation (What are the unique challenges anticipated with implementing immunization against Zika once a vaccine is available?). We request you provide your experience and expertise to the development of this Special Issue and valuable addition to the medical literature. A number of individual topic reviews have been previously published but I believe this issue will be unique because of its breath, exploration not only what we know but what we do not know, and because of your collective expertise.

Prof. Stephen J Thomas
Guest Editor

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• Zika
• virus
• vaccine
• congenital
• Guillain-Barre
• pre-clinical
• clinical