What do the couplets of pet vaccines mean?

The combination of pet vaccines refers to the ability to prevent several diseases. For example, a single vaccine can prevent one disease, and if two single vaccines are injected together, the vaccine can prevent two diseases. This is called a two-part vaccine. The two-part vaccine protects against canine distemper and canine parvovirus. The quadruple vaccine can prevent canine distemper, canine parvovirus, canine parainfluenza, and canine adenovirus.

A vaccine is actually a weakened, less active or inactivated version of the virus. After being injected into dogs, the weakened and inactivated virus cannot affect healthy dogs due to their resistance, but it can stimulate the production of antibodies against the virus in dogs, making them more vulnerable to stronger viruses in the future. The increased antibodies are enough to cope.