Why are we able to completely eradicate some viruses through vaccines but not others?

Question

Smallpox for example and Polio (almost)

In: 2

Answer 1

Both of these efforts you have mentioned took billions of dollars and decades of hard work. It is not just about the money but also the political capital needed to prioritize vaccinations all over the world. If just a single region is not vaccinated enough the virus will not be eradicated. Some of the efforts involved in these vaccination programs have involved negotiating ceasefires in civil wars and open up closed areas to health workers. It have been an enormous effort to complete just one of these programs. So we are prioritizing each virus one by one in order to focus all our efforts on a single program instead of spreading out our efforts making half attempts at each and failing.