FIGURE 1.

Evolution of vaccine development processes: Vaccine development was pioneered by Edward Jenner. He discovered a working vaccine against small pox in 1796 derived by variolation and further work was continued by Louis Pasteur. He has discovered a live attenuated vaccine against Rabies virus in 1885 considered to be one of the 1st generation vaccines. It was followed by a genomic revolution and in the post-genomic era, mankind witnessed the modern sequencing techniques. In early 21st century, Rappuoli introduced Reverse Vaccinology (RV) approach which provided a foundation to the development of 2nd generation vaccines (Rappuoli et al., 2016). Since then, advances in various ‘omics-based’ approaches together with RV led to the development of a much more advanced 3rd generation of vaccines in the present times. Different vaccines derived from variolation, live attenuated, inactivated, toxoid, DNA recombinant have been shown in the timeline.