Exactly how is a population increase going to help these people?
I think it's an error to think that vaccination will lead to a population increase over the medium term. In developed nations, family sizes dropped sharply as childhood survival rates increased, in nations where you can reasonably expect a child to survive to adulthood people tend to feel less need to have large families, and instead invest more heavily in a smaller number of children.
In poor countries where famine is an issue, for example, it means that the population will increase to an even more unsustainable level, compounding the problem and requiring more food aid.
That's my objective view on it, even though it's good to help others if we can afford it.
Don't forget that your historically (and current) high standard of living comes from exploiting the resources/labour markets of the poor countries of the world.
This is a drop in the ocean back from what we have exploited to fund our way of life.
The point is what we class as "struggling" and what the poor countries class as "struggling" are not even on the same planet.
We are on the whole warm, fed, have electricity & running water....when we don't have those things as standard we can class ourselves as struggling.