Final answer:
The significant decline in rates of measles, rubella, and tetanus is attributed to vaccinations, which have been vital in controlling infectious diseases through immunization.
Step-by-step explanation:
The public health initiative that resulted in the drop in rates of measles, rubella, and tetanus is attributed to vaccinations. By utilizing the adaptive immune system, immunization has been the most effective method in preventing these infectious diseases. This initiative has led to the near eradication of diseases like polio and measles in many parts of the world. The introduction of artificial immunization programs and vaccination campaigns has significantly reduced the incidence and mortality rate of infectious diseases by assisting the body in developing immunity against them.