I'd like to hear from antivaxxers their positioning on the eradication of smallpox through a 28-years-long worldwide campaign.

Smallpox is a disease that affected 15 million people per year in the 60s and killed around 2 million of those. Therefore, had that proportion maintained, smallpox would have killed as many as 80 million people nowadays.

Worth mentioning is that since Ancient China inoculation has been a treatment/preventive measure used against smallpox, decreasing mortality by around 40 times.

Source.