The number of measles cases in Montana has grown to 17.
Gallatin County public health officials last week announced that a fully vaccinated person contracted measles from an unknown source.
Public health experts say while that can happen, it’s rare. The measles vaccine is considered 97% effective. That means three out of every 100 vaccinated people will contract the virus.
Some people don’t fully respond to the vaccine, or have compromised immune systems.
"It’s for that reason that we want to make sure that we maintain high vaccination rates in communities, because there are certain groups that we want to protect,” says Sophia Newcomer, professor of epidemiology at the University of Montana.
Newcomer says Montana’s measles vaccination rate is estimated to be about 90%. That’s shy of the 95% mark, which is considered herd immunity. While that gap might seem small, she says it’s quite large for measles, which is the most infectious disease we know of.
Newcomer says if you’re unsure about whether you’re vaccinated, talk to your provider about getting the shot.