Final answer:
The first live vaccine for kids is the polio vaccine, which led the way for other childhood vaccines against diseases like measles, mumps, and rubella, keeping these once-common diseases rare today.
Step-by-step explanation:
The first live vaccine that was routinely given to children was the polio vaccine. Mass immunization campaigns utilizing the polio vaccine began in the 1950s with a killed vaccine and continued in the 1960s with a live vaccine. This significantly reduced the incidence of polio, which was previously a disease that caused considerable fear due to its ability to cause muscle paralysis in children during regional epidemics. The creation and success of the live polio vaccine created a pathway for the development and routine administration of other childhood vaccines for diseases such as measles, mumps, and rubella. It's important to mention that although the live polio vaccine was a major milestone, children in many places now first receive a vaccination at birth against Hepatitis B, which is not a live vaccine but a recombinant one. Additionally, the impact of vaccination programs has made once-common diseases like measles, mumps, and polio rare today, which is why immunization campaigns are still essential to maintain the health of the population.