As a COVID-19 vaccine is being rolled out, we should all have a greater appreciation of immunological memory, the primary rationale for the development of vaccines against infectious microbes. The basis for immunological memory can be traced back to the ancient Greeks and the plague of that time, when survivors of the infection did not experience the disease again and were often called upon to nurse the afflicted individuals.
This early observation led to the concept of inoculation or variolation, which became a common practice in certain parts of the world and was introduced to Europe around the 18th century through the Royal Society. Lady Mary Wortley Montague was responsible for leading variolation in England where in 1722 the daughters of the Prince of Wales were inoculated.
Just a year prior, in 1721, the practice of variolation had reached the colonies when inoculation against smallpox was championed by the Rev. Cotton Mather and Dr. Zabdiel Boylston, a great uncle of President John Adams.
In 1796 country doctor Edward Jenner made a seminal observation that dairymaids who were exposed to cowpox never came down with smallpox. This observation led to the concept of vaccination, and these findings were published in 1798.
In 1840 vaccination replaced the practice of variolation, and in 1977 the World Health Organization led a global effort to successfully eradicate smallpox. A similar worldwide immunization effort with two different vaccine platforms (akin to the different COVID vaccines) led to the suppression of polio in the 1960s. Similar successes around the world are evident by several efforts, including Gavi, the Vaccine Alliance, which provides critical childhood vaccines in the world’s poorest countries and prevents millions of deaths.
Immunologic memory and specificity are important characteristics of learned or adaptive immunity, where the immune system remembers antigens from past exposure and launches a robust immune response when the same antigen is seen again. These features of the immune system are intrinsic in humans and form the basis for the development of vaccines against microbes that have historically caused epidemics and transformed society.
The pressing need for further investments in infectious disease research is evident by the ease of global travel, the rise of world population, human behavior, and changes to climatic patterns with spread of insect vectors that have impacted microbial ecology and transmission patterns of infectious microorganisms.
The current pandemic has amplified the power of international coordination and cooperation. The genetic sequence of SARS-CoV-2, the coronavirus that causes COVID-19, was published in early January 2020. This catalyzed research and development into the generation of promising vaccines for mass production in under a year.
Such innovation will further spur opportunities in the design of next-generation vaccine platforms for evolving future major public health concerns that will be at the forefront of public attention and collaborative private-government action.
