Why there has been a decrease in the number of deaths among children in recent decades.?

Answerunderstanding what advocacy means and looks like in action;

True, this is when someone has mood swings

Immunization is the introduction of a foreign substance to provoke  the immune response system.  immunizations are the same as vaccinations. it introduces foreign (but dead/ weakened) illnesses to train the body to fight against them. specific viruses and bacteria have specific antigens, antigens act sort of like name tags. these name tags the immune system recognize what's dangerous to the body and what's safe.