Transcript for What parents should know about measles outbreak as kids head back to school
We have a "Gma" health alert on the worst measles outbreak in 25 years with children heading back to school. New numbers from the CDC show more than 1200 cases across 30 want too bring in our expert Dr. Jen Ashton coming to us from Vancouver. Thanks for joining us again. So we're heading back into the school year right now. Let's break it down by age group. What should parents of preschoolers know? So, George, when you talk about that age group let's remember what the vaccination schedule normally is. First dose of the measles vaccine normally given between the ages of 12 and 15 months. That gives 93% protection. The second dose normally given between 4 and 6 years of age, that brings the efficacy up to 97% in on outbreak situation according to the CDC. One dose is enough to stop the outbreak, so, again, it's a reminder how important, how effective and how safe vaccination is. What about little babies? Is there any protection for them? So different recommendations when you talk about infant, George. This is a very vulnerable group because normally the first dose is not given before 12 to 15 months. The CDC responded to this outbreak, put forth kind of emergency recommendations for infants at high risk so those would be babies traveling internationally where there are massive measles outbreaks going on and infants who may be in an outbreak area geographically, they can get an early dose at 6 months of age all the way up until they turn 1. They will still need two doses then later on but this is, again, speaks to the fact of how seriously the CDC is taking this outbreak. Yeah, we're all learning how, again, how contagious measles can be so what if you haven't been vaccinated, you find out someone in your kid's school or community has contracted measles. Well, first of all, recommendations are not to go to the emergency room because this is such an infectious virus that you don't want to expose other people who may be very, very vulnerable to measles. So call your health care provider but there's something called post-exposure prophylaxis where if you have been exposed you can get a dose within 72 hours. There is some data that suggests it may reduce your chances of getting sick. If you do get sick it may lessen the severity but we have to be crystal clear, there are cases of people being furloughed from work, maybe from school as well for a period of two to three weeks if they can't provide documentation that they've been vaccinated or if they haven't been vaccinated, it tells you how serious this outbreak is. Boy, it sure is. Jen Ashton, thanks very much.
This transcript has been automatically generated and may not be 100% accurate.