Thanks! As I pointed out in another comment here, as far as I am aware, the main comment that people point to from Gates regarding 'lowering the population' in relation to vaccines was most likely a reference to the fact that people in poorer areas often have large families to attempt to counteract the high mortality rate due to childhood diseases. He is claiming, as far as I am aware, that vaccinations therefore are a good thing because they protect children and so therefore less children will be born as a result.
All that said, his father was head of 'planned parenthood' which has been identified in quite a reliable way to have been formed by eugenicists, rather than by 'concerned pillars of society' - so I remain totally open as to exactly what his real agenda is!