Bid rent theory in the central business district (CBD) [edit]. Land users, whether they be retail, office, or residential, all compete for the most accessible land within the CBD. The amount they are willing to pay is called bid rent.
Recombinant or purified protein vaccines consist of protein antigens that have either been produced in a heterologous expression system (e.g., bacteria or yeast) or purified from large amounts of the pathogenic organism.
MMR is a live attenuated vaccine. This means that it contains the living viruses, which have been altered in such a way as to prevent the vaccine from actually causing the diseases. However, the body's immune system still responds to it, providing future protection against infection.