“Prevention is better than cure”, the sole concept of vaccination is based on this idea. Many deadly diseases like Small pox, Polio have already been eradicated by administering these wonder products. The first vaccine against small pox came into existence long back in 1796 when Edward Jenner followed up his observations that milkmaids who had previously caught cowpox (caused by a virus similar to smallpox) were never affected by smallpox. Thus, the smallpox vaccine was a live vaccine made from Vaccinia virus and was administered in lyophilized form using a bifurcated needle.
How often do we see bifurcated needles these days? Majority of the vaccines are administered using injections and some orally (e.g. Polio). They are either killed or attenuated to prevent any severe immunological reactions. Apart from these, we also have subunit vaccines which contains only the antigenic protein responsible for causing the infection. Owing to the advancements in the chimeric DNA technology, DNA and RNA vaccines have been developed in which the infectious gene containing plasmids are given as vaccines.
So yes, definitely vaccines have come a long way from the time they first came into being. But there's more to come. Scientists are carrying out research to develop Edible vaccines, the procedure being similar to that of producing transgenic plants using Agrobacterium tumefaciens. Well, maybe the day is not far when eating your favorite vegetable would immunize you against a dreadful disease!
T. Y. B. Pharm