What are vaccines?
Vaccines are medications that are designed to stimulate the body's immune system to generate a response that will protect the individual from disease caused by the pathogen in question.
The first vaccination
The first vaccination was performed by Edward Jenner who had noticed that dairy maids who had had cowpox infection (Vacca = cow in Latin) did not succumb to the deadly smallpox infection that was claiming many lives at the time.
To test his theory, Jenner infected his gardener's son, James Phipps, with cowpox and then weeks later attempted to infect him with the deadly smallpox. Happily, James survived the experience and was protected from infection and thus the practice of vaccination was born.
Vaccines and the immune system
The body's immune system is comprised of two arms - antibody-mediated immunity and cell-mediated immunity. All vaccines developed in the last 50 years probably protect by stimulating a potent antibody response. However, for pathogens that live within cells of the body, where antibodies can't reach, it is likely that cell-mediated immunity is required for protection. Examples of such pathogens include malaria, TB and HIV. Each of these is a huge global health problem claiming millions of lives each year for which there is no effective vaccine.
The ideal vaccine
The ideal vaccine would be:
1. Safe with no or few side-effects
2. Easy and cheap to manufacture
3. Stable for storage/transport
4. Easy to administer
5. Could be given to infants (ideally alongside other childhood vaccinations)
6. Would stimulate life-long protection against all forms of the disease