Iceland experienced one of its deadliest outbreaks of smallpox beginning in 1707. The epidemic ultimately killed around 12,000 Icelanders, close to one-quarter of the island's population at the time.

Iceland in 1707 was a territory of the Kingdom of Denmark with 53,681 people according to one tally of the 1703 census.^[2] Epidemic diseases like smallpox did not naturally sustain themselves on the island due to the relatively sparse population, but frequent trade and travel with Denmark presented a vulnerability to cross-Atlantic spread of contagious diseases. Smallpox had crossed the ocean before in 1670, causing a two-year epidemic, and since then a new generation of people had developed with no immunity to the disease.^[3]

In 1707, smallpox arrived in Iceland aboard a ship from Denmark when a passenger fell sick and died with the disease. Despite being buried at sea, the index case's contaminated clothing remained and infected at least one other person on board.^[1] The next year it had spread to almost every town across Iceland. The last reported cases were in the spring of 1709. Ultimately, the outbreak may have killed a quarter of the population of Iceland at the time.^[1]