For many years, humanity's approach to combatting infectious disease was similar to that of building a wall made with blocks of inactivated pathogens. These were the key materials of early vaccines, which worked by providing a weakened version of the pathogens, safely allowing the body to arm itself for when it encountered the actual disease. However, this slowly-built wall was often penetrated by newly evolving pathogens and failed to provide foolproof protection. Here, modern vaccine engineering emerged, providing a strengthened guard protecting the body. Vaccine engineering has yielded an improved way to arm the body, not by providing a weakened version of the disease, but by providing a simple instruction manual for combat.
Now, vaccines save 5 million lives every year; this number is only expected to grow in the future with further development [1]. From the initial variolation concept in Asia to Edward Jenner’s first small-pox vaccine, then to Pasteur’s lab methods, vaccination has now reached a new peak in development: vaccine engineering. With the emergence of genetic engineering in the 20th century, vaccine development has been revolutionized, creating new approaches to synthesize antigens (such as in the hepatitis B vaccine) and to create safer live bacterial vaccines by removing particular dangerous genes. This revolution has led to contemporary vaccine engineering, where innovations such as mRNA technology and virus-like particles are the solid way to disease prevention, also allowing for the efficient accelerated manufacturing of vaccines [2].
As part of the new approach to vaccine development, the content inside vaccines has changed significantly. As mentioned above, vaccines used to work by exposing the human body to weakened or killed versions of a pathogen, so that the immune system could learn to recognize and fight it. Although this method was effective against diseases like polio, measles, and smallpox, it was a time-consuming process of growing and then inactivating a virus, in turn posing a greater risk for people with a weak immune system. Nowadays, many vaccines no longer rely on pathogens. Many modern vaccines utilize mRNA technology. Messenger ribonucleic acid, or mRNA, is a molecule in cells that copies instructions from DNA to the ribosomes to be made into proteins [3]. Vaccines with mRNA carry the instructions for creating specific parts of the pathogen, allowing the body to create a recognizable part of the pathogen and identify it as an invader. The body can then produce antibodies to fight off the infection more efficiently the next time it detects that same protein.
An equally important transformation has been large‑scale production of vaccines. This increase in production can be attributed to new technology, such as computer modeling tools and synthetic DNA creation. Computer models are used by scientists to predict which parts of a pathogen may be recognized by the immune system and its complex line of defense; they help scientists choose which parts of a pathogen to include in vaccines that will spark the body’s immune response [4]. To continue, synthetic DNA creation for vaccines allows for rapid, cell free production with no need for live pathogens. These developments allow factories to manufacture larger numbers of vaccine dosages in shorter amounts of time. During the COVID‑19 pandemic, production of vaccines skyrocketed from 0 to 11.2 billion doses in just one year, allowing countries to launch the vaccines earlier than expected and protecting people across the world from the spread of the disease [5].
New developments for engineered vaccines offer more effective and efficient solutions to the previous methods. Paired with advancements in manufacturing and production, vaccines now have a much greater impact on global human health, exemplified through the role of vaccines in combating and overcoming the recent COVID-19 pandemic. With a current shift into AI-driven formula optimization and antigen identification, scientists are taking great steps to ensure a future of improved public health and safety.