Herd immunity is not junk science or a false theory. Herd immunity is real, it works, and explains how people in a community are protected from a disease when vaccination rates are above a certain threshold.
One hundred years ago, misinformed and irresponsible parents were deceived by false propaganda and deliberate misinformation, leading to outbreaks of smallpox.
There is no question that there is great value in getting fully vaccinated on time and that getting immunized is a very cost effective way to keep kids healthy.
Yellow fever is still a risk in area of Africa and South America, so be sure to find a yellow fever vaccine, even might be hard with the current shortages, if you are traveling to a high risk area.