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.
Flu vaccine is an inactivated vaccine, meaning that it contains killed influenza virus. The killed influenza virus is injected into muscles or skin and stimulates the immune system to produce an immune response (antibodies) to the influenza virus.