Dear Colleagues,

Vaccines are one of the most powerful and effective healthcare advances ever developed. Nevertheless, the most effective vaccine candidate for an economical price is still lacking for developing-world populations. Several factors limit complete global immunization and among these is the cost of procuring and distributing vaccines in lower-income countries. In this view, the topic focuses on the development of an economical vaccine candidate against infectious diseases for humans and animals for the global public good. Therefore, a new strategy is required to induce a broad range of protective immunity against bacterial, fungal, or viral pathogens. In particular, we need to develop a vaccine technology platform, targeting quality, efficacy, safety, simplicity, cost-effectiveness, and affordability. Possible vaccine candidates include live attenuated vaccines, inactivated vaccines, subunit vaccines, toxoid vaccines, conjugate vaccines, DNA vaccines and recombinant vector vaccines. Recently, researchers worldwide have developed new vaccines against SARS-CoV-2, the virus causing the COVID-19 pandemic. There are two main approaches to designing a vaccine. A vaccine produced by Pfizer or Moderna is made using mRNA, a technology that delivers mRNA instructions for cells to build the surface protein (spike) of SARS-CoV-2. Another vaccine produced by J&J or AstraZenaca is a viral vectored vaccine to instruct human cells to make the SARS-2 spike protein, which then triggers an immune response. A harmless adenovirus has been engineered to carry the genetic code for the SARS-2 spike protein. Once the adenovirus enters cells, they use that code to make spike proteins.

In this Special Issue, possible approaches cover the fundamental discovery of vaccine candidates and their delivery systems through to their preclinical/clinical trials. In addition, the topic includes normal immunologic responses to vaccination, patterns of abnormal responses, and methods for assessing these responses. The immune response should include a general evaluation of the immune system, including measurements of antibody levels and functional assessments of different immune cells, as well as cytokines. I wish to thank all authors for their contributions to this Special Issue.

Prof. Dr. Chang Won Choi
Guest Editor

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• Vaccine candidates
• Broad range of protective immunity
• Vaccine technology platform
• Immune responses
• Delivery system
• Discovery, preclinical and clinical trials