The traditional types of vaccines are tried and tested, have been around for a long time, are safe and work very well, so some question the need for these next-generation vaccines. The answer is that the more traditional vaccines have limitations in terms of how quickly they can be developed, how flexible they are at being adapted to new viral variants, and the cost and speed at which they can be manufactured. 

We had been battling infectious and harmful viruses long before SARS-Cov-2, the virus causing COVID-19, came along –examples include Ebola, influenza, zika, rabies, MERS, SARS-CoV and HIV. Indeed, the emergence and rapid spread of other coronaviruses, such as MERS and SARS-CoV had demonstrated to scientists that we needed a new way of designing vaccines if we wanted to react quickly to the emergence of any new viruses in future. DNA and mRNA-based vaccines helped address the shortcomings of more traditional vaccines in this regard, and so by the time COVID-19 emerged, scientists had already been building the foundations for these types of vaccines for decades. 

When SARS-CoV-2 emerged in December 2019, all the viral vaccine research around the world shifted focus to a single virus and using the knowledge accumulated over several decades, together with unprecedented funding and collaboration, we were able to produce very effective and safe next-generation vaccines against SARS-CoV-2.