It was a warm day in May 1796 when the English physician Edward Jenner (1749-1823) vaccinated an 8-year-old English child named James Philip. Infectious material from a young woman suffering from cowpox was inoculated into James’ body by Mr Edward. Months later, Dr Jenner inoculated the human Smallpox virus into James’s body. The child did not get infected, and both Edward and James witnessed one of the most remarkable innovations in vaccination.
How do vaccines work?
Even though Edward Jenner was unaware of the biological mechanisms behind immune biology, modern immunology teaches us that vaccines rely on a principle called immunological memory. We memorise the faces and habits of people we have met and act with them based on our precedent experiences. Similarly, vaccines mimic the first interaction with a pathogen (the organism responsible for the disease), thus stimulating a quick and fast immune response in case of future exposure. With this biological process fixed in their mind, scientists have been introducing numerous innovations in vaccination for 200 years and more.
Past and current innovations in vaccination: different types of vaccines
Vaccines are usually classified according to their components.
- Attenuated vaccines (i.e. Sabin‘s polio vaccine, 1954) contain viable viruses with reduced virulence
- Inactivated vaccines (i.e. Salk‘s polio vaccine, 1952) are composed of viral particles from cultured viruses previously killed to attenuate their pathogenicity
- Subunit vaccines (i.e. vaccines against diphtheria and tetanus) inoculate into the human body structural elements of pathogens recognised by the immune system
- DNA or mRNA vaccines (i.e. vaccines against SARS-CoV-2 developed in 2020) contain fragments of viral DNA or mRNA, depending on the nature of the virus or the vaccine
Future innovations in vaccination: mRNA vaccines
RNA-based vaccines have gained importance during the SARS-CoV-2 pandemic. While “canonical” vaccines contain pathogens or proteins, mRNA vaccines use messenger RNA (mRNA) to activate the immune response. mRNA is a biological molecule known to carry instructions to make proteins. Once a person gets immunized, mRNA gets translated, triggering a series of biological processes leading to immune response and immunological memory. mRNA vaccines are safe and reliable, have low production costs, and rapid development. Finally, mRNA vaccines have proven to be effective against several types of cancer.
Many years have gone by now since Edward Jenner vaccinated James Philip, giving a start to a long history of innovations in vaccination. Thanks to this remarkable event in human history, we can develop safe and reliable vaccines in a heartbeat. On top of that, several laboratory and clinical studies are reporting that vaccines may be the key to treating different types of cancer.
- Pardi, N., Hogan, M., Porter, F. et al. mRNA vaccines — a new era in vaccinology. Nat Rev
Drug Discov 17, 261–279 (2018)