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.
The MMR vaccine is an immunization vaccine against measles, mumps, and rubella (German measles) . It is a mixture of live attenuated viruses of the three diseases, administered via injection. licensed vaccine to prevent measles first became available in 1963, an improved measles vaccine in 1968. Vaccines for the mumps and rubella became available in 1967 and 1969, respectively.