Similar events took place in Oceania and Madagascar. Smallpox was externally brought to Australia. The first recorded outbreak, in 1789, devastated the Aboriginal population; while the extent of this outbreak is disputed, some sources claim that it killed about 50% of coastal Aboriginal populations on the east coast. There is an ongoing historical debate concerning two rival and irreconcilable theories about how the disease first entered the continent - see History of smallpox. Smallpox continued to be a deadly disease, killing an estimated 300 million people in the twentieth century alone, though a vaccine—the first of any kind—had been available since 1796.