This is exactly why meme culture is driving us off a cliff. Whoever made this meme is either being intentionally deceptive, or they don't know what they are talking about. The highest causes of childhood death in the 1900s were pneumonia, influenza, tuberculosis, and diarrhea{Starvation is not listed, but I bet it was a major contributor for many, especially before 1900}
The credit for less children dying belongs with better health care, better health care facilities, and more knowledge all around. And a better food system. Not vaccinations. Many conditions are very treatable that were an absolute death sentence in the past.