Abstract

Vaccines proved to have great impact in public health as they exert primary prevention level
in preventive medicine. Their implementation resulted in the eradication of smallpox, near
eradication of polio, control of several infectious diseases as well as prevention of millions of
deaths each year. They are one of the most effective public health measures available in
case of infectious disease. Vaccines development started as early as the end of the
18thcenturyby Edward Jenner who used cowpox-infected materials to immunize against
smallpox and introduced the term “vaccine”. Louis Pasteur refined Jenner’s work and
introduced the basic principles of vaccination represented by pathogen isolation,
inactivation/attenuation and injection. The introduction of cell culture for virus propagation
enabled the development of methods for attenuating viral vaccines resulting in a golden age
of first vaccines development that occurred in the second half of the 20thcentury and
licensure of vaccines against polio, measles, mumps, rubella and varicella. Vaccines
developed by inactivation/attenuation of infectious agents are termed
conventional/traditional vaccines. The second renaissance of vaccine development was
introduced by the development of subunit vaccines for which only parts (protein/peptide,
carbohydrate antigens) of target pathogens are used to induce appropriate immune
responses. The targeted subunit has to be abundant and conserved in the pathogen,
recognized by the immune system and able to elicit a protective immune response. The
antigenic part of a subunit vaccine can be prepared by either isolating a specific component
from the pathogen or synthesis of specific protein by molecular genetic techniques. This
allowed the development and licensure of vaccines against Haemophilus influenza type B;Meningococcus A, C, W, and Y; Pneumococcus; as well as the introduction of acellular
pertussis vaccine, hepatitis B surface antigen (HBsAg) and bivalent or quadrivalent human
papilloma virus (HPV)vaccine. The latest renaissance in vaccine development was started to
develop vaccines that induce protective immunity beyond the mechanisms evolved by
nature against pathogens exhibiting hyper variability (influenza, dengue, HIV-1, HCV), their
conventional vaccines exacerbate disease (RSV, dengue) or those leading to
persistent/latent infection or have an intracellular phase such as (HIV-1, hepatitis C virus
(HCV), cytomegalovirus (CMV), herpes simplex and Mycobacterium tuberculosis and
malaria as well as emerging pathogens. New technologies have to be developed for next
generation vaccines development against pathogens that fail to induce sterilizing immunity
as well as currently emerging ones. These technologies can be divided into three major
categories related to antigen discovery, adjuvants and vaccine delivery, and deciphering
human immune responses. Reverse vaccinology, genomic-based antigen discovery
(antigenome analysis), structural vaccinology/reverse engineering of vaccines and synthetic
biology support antigen discovery while viral vector-based vaccine, nucleic acids vaccines
and liposomes can encompass vaccine delivery technologies. Platform technologies have to
implemented to act as modular vaccine platforms that accelerate safe vaccine
manufacturing at low cost to be used in potential pandemic settings.