The Central and Southern Coast Salish of the Georgia Strait and Puget Sound Area suffered a 42 percent population decline during the century following the the first outbreak of Smallpox in 1775.

Estimates of the pre-epidemic population of the Songhees and Saanich people is 1,050; post epidemic population is estimated at 486.

Smallpox epidemics occurred in 1775 (as recorded by explorers Vancouver and Puget); in 1801; 1824; 1853 and 1862-63. The introduction and use of smallpox vaccine - particularily around the missions, Hudson's Bay forts and other populated areas helped control the effect and spread of the disease by 1853.

"Total precontact population for the Georgia-Puget Epidemic Area is estimated at 29,599."

By 1820 this precontact estimate had been halved, and after a century it had decreased by over two-thirds.... It should benoted that population decline here is the smallest estimated for any epidemic area on the Northwest Coast.... When vaccination and effective health care systems were introduced in the mid-nineteenth century the natural tendency to increase seems to have reassurted itself."

(p. 145/146 Boyd, Robert T.; "Demographic History, 1884-1874" from Suttles, Wayne ed.: The Handbook of North American Indians, Volume 7; Northwest Coast; Smithsonian Institution, Washington, 1990)