two or more vaccines administered in a single dose (MMR and DTP vaccines, for example).
A single preparation in which more than one vaccine is present, e.g. MMR (measles, mumps and rubella) and DTP-HIB (Diptheria, tetanus, pertussis, and HIB).
Two or more vaccines administered at once in order to reduce the number of shots given. For example, the MMR (measles, mumps, rubella) vaccine.