∞ generated and posted on 2016.01.01 ∞

Prophylactic application of an immunologically active but otherwise somewhat harmless material for the sake of either priming or boosting an immune response.

Vaccination is the exposure of a body to a pathogen or part of a pathogen (or parasite) that has been otherwise rendered harmless but which still can elicit an active immune response, one which ideally is protective given subsequent exposure to the same pathogen (or parasite).

This immune system priming can be against a pathogen, bacterial toxin, or other potential harmful biological entity. See equivalently immunization.

Vaccines can be differentiated into those that are alive (i.e., live-attenuated vaccine, a.k.a., attenuated whole-agent vaccine) versus those that are whole but dead (whole killed vaccine, a.k.a., inactivated whole agent vaccine) versus those that are both dead and variously dismembered (acellular vaccine, subunit vaccine, and/or recombinant vaccine; see also DNA vaccine and toxoid).

Live attenuated vaccines in effect have in a sense been partially genetically inactivated. Whole killed vaccines as well as toxoids have been destroyed in terms of their anti-body properties, typically using the aldehyde, formalin. Recombinant vaccines have been modified using genetic engineering, etc.

With DNA vaccines, DNA that encodes proteins which otherwise are associated with pathogens are inserted into body cells such that these protein-encoding enes are then expressed. This can elicit a strong immune response, particularly one consisting of what is known as cellular immunity as otherwise usually seen particularly with live-attenuated vaccines. Elicited as well is humoral immunity, as seen with other vaccine types.

The resulting priming of cellular immunity is particularly impressive since it can be achieved, with DNA vaccines, without exposing the individual to living and thereby potentially dangerous pathogen.

The following video cleverly makes the case for childhood vaccination, in a song: