Final answer:
The first live vaccine given to children was the polio vaccine in the 1960s, which helped significantly reduce the incidence of polio. It marked a turning point in child immunization and led to the widespread use of vaccines against many other diseases like measles, mumps, rubella, and chickenpox.
Step-by-step explanation:
First Live Vaccine for Children
The first live vaccine for children that represents a significant milestone in vaccine development is the polio vaccine. The mass immunization campaigns of the 1950s initially used a killed vaccine, but it was the introduction of the live vaccine in the 1960s that notably reduced the prevalence of polio. Polio is a disease that can cause muscle paralysis in children and was much feared during regional epidemics. The use of the live vaccine led to the success of the polio vaccination effort, which has paved the way for the routine administration of other live viral vaccines against diseases such as measles, mumps, rubella, and chickenpox.
In many countries, the first vaccine a child receives is the Hepatitis B vaccine at birth, providing protection against Hepatitis B, a serious liver disease. Subsequent vaccines continue to protect children from fatal infections that have now become rare due to the wide coverage of vaccination programs.