Lessons > Vaccination > For Your Consideration
Vaccinating a population has a similar effect to changing the population density. An immune person is no longer a vehicle for transmitting the disease, thus lowering the effective density of the population. Since we can't control population density in most cases, vaccination is one of the best means to prevent the spread of disease, not just to the vaccinated individuals, but to the population as a whole. Stopping or slowing the mixing of people, via quarantine, or closing businesses and schools, is also an option, with similar net effect. Although the common cold doesn't have a vaccine available, you may choose to return to the simulator and experiment with the possibilities of immunizing a percentage of your population to Kold.
There are four main types of vaccine: those containing a killed pathogen, those containing live strains of a pathogen, those containing toxoids (the compounds produced by a pathogen that cause a human reaction, as opposed to injecting with the microorganism), and those containing subunits of the pathogen (such as antigens or other proteins that create part of the physical makeup of the microorganism). Newer genetically targeted vaccines are being developed, but although preliminary tests look very positive, the constantly mutating genetic makeup of the more dangerous diseases prevents us from distributing a vaccine without caution.