SALT LAKE CITY — Utah is the worst state in the country for measles cases per capita, and the numbers behind that distinction reveal how dramatically the state's vaccination landscape has shifted over the past 15 years.
Nationally, there have been 2,465 measles cases so far this year. Utah and South Carolina together account for 48% of those cases. On a per-capita basis, Utah is the nation's hottest hot spot for measles outbreaks.
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The state's vaccination rate tells a significant part of the story. In 2009 and 2010, Utah had the seventh-highest kindergarten vaccination rate in the nation at 97.7%. Last year, that rate had fallen to 88.6%, ranking Utah 43rd in the country — the third-biggest decline in vaccination rates of any state over that period.
That matters because measles requires 95% vaccination coverage to achieve herd immunity. Utah is now well below that threshold.
The outbreak is concentrated in three health districts: the Tri County District of eastern Utah, the Central Utah Health District, and the Southwest District. Those districts represent 12% of Utah's population but account for 64% of the state's measles cases. In those rural outbreak districts, one in every 1,000 people has already caught measles during this outbreak. On the Wasatch Front, that figure is one in 13,000.
Measles by the numbers in Utah:
Vaccination status is a defining factor in individual risk. Of unvaccinated Utahns, about one in every 440 has caught measles. For vaccinated Utahns, that figure drops to approximately one in every 47,000.
In total, 617 unvaccinated Utahns have gotten measles in the last two years while 68 vaccinated Utahns have been confirmed with the disease. In 30 cases, vaccination status is unknown. The state counts someone as vaccinated if they've gotten one or more shots, though guidelines recommend getting two.
