Mixed vaccine refers to a combination of different vaccines that are used to protect against different diseases. Some synonyms for mixed vaccine include combination vaccine, multi-valent vaccine, and polyvalent vaccine. Combination vaccine is a term used to describe a vaccine that contains multiple antigens and is administered to protect against several diseases at once. Multi-valent vaccine is a more technical term that refers to a vaccine that contains multiple strains of the same pathogen. Polyvalent vaccine is a term used to describe a vaccine that targets multiple strains or types of pathogens. Regardless of the word used, mixed vaccines have proven to be an effective way to protect against a range of diseases.