SANTA ANA, Calif. (KABC) -- The Orange County Health Care Agency has confirmed its first case of measles in 2019.The agency says a woman in her 20s, who is a resident of Placentia, reported recent travel to Vietnam, one of the many countries experiencing widespread measles activity. Officials say the woman is a rare case because she was fully vaccinated.The unidentified woman is considered infectious between the dates of April 23 and May 1. She is currently under voluntary isolation at home.Authorities said the woman went to see "Avengers: Endgame" last Thursday at 11 p.m. at the AMC Movie Theater on Lemon Street in Fullerton.Orange County residents may have been exposed to measles since the woman visited public locations while infectious."Measles is one of the most infectious viruses that we know of out there, so a lot of people exposed if not protected by vaccination will come down with the disease" said Orange County Interim Health Officer Dr. Nichole Quick.Questions related to measles or potential exposure may call the HCA Health Referral Line at 1 (800)-564-8448.Below are the exposure locations and times:5 Hutton Centre Dr., Santa Ana, CA 92707-April 23 - 25 from 7:45 a.m. to 7:15 p.m. dailySt. Jude Emergency Department, 101 E. Valencia Mesa Dr., Fullerton, CA 92835-April 27 from 7 a.m. to 9 a.m.AMC Movie Theater, 1001 S. Lemon St., Fullerton, CA 92832-April 25 from 11 p.m. - April 26 at 4 a.m.People who were in the location above around the same time as the woman with measles should review their vaccination history and monitor themselves for illness with fever and/or an unexplained rash from seven days to 21 days after their exposure.