Measles cases are spreading across the country.<\/p>\n
Doctors share what to do if you\u2019ve been exposed to the virus. <\/p>\n
Plus, what infectious disease doctors want you to know about the disease.<\/p>\n
Public health officials in New Jersey<\/a>, Massachusetts<\/a>, and Colorado<\/a> have recently sent out warnings of travelers infected with measles passing through busy airports and other areas. Couple that with measles\u2019 ability to spread rapidly, and it\u2019s understandable to have concerns about the disease. <\/p>\n \u201cMeasles is extraordinarily infectious\u2014if you\u2019re susceptible,\u201d says Thomas Russo, M.D.,<\/a> a professor and chief of infectious diseases at the University at Buffalo in New York.<\/p>\n Each year, a small number of measles cases pop up in select areas around the country. But the past 12 months have been different. Nearly 2,100 people across 44 states were impacted by measles in 2025, according to data shared by the Centers for Disease Control and Prevention<\/a> (CDC). That\u2019s the highest number of cases in 25 years<\/a>. Unfortunately, cases continue to surface.<\/p>\n Meet the experts: John Sellick, D.O.<\/a>, an infectious disease expert and professor of medicine at the State University of New York at Buffalo; Amesh A. Adalja, M.D.<\/a>, an infectious disease expert and senior scholar at the Johns Hopkins Center for Health Security; Thomas Russo, M.D.,<\/a> a professor and chief of infectious diseases at the University at Buffalo in New York.<\/p>\n These warnings about exposures keep coming, making it fair to wonder what this means for you. Here, infectious disease doctors break down some of the most pressing questions people have about measles, plus what to do if you are exposed.<\/p>\n Why is measles so contagious?<\/p>\n While there are outbreaks across the country each year, most people aren\u2019t overly familiar with measles. Also known as rubeola, measles is a highly contagious respiratory virus, according to the CDC<\/a>. It may cause symptoms like a cough, runny nose, red and watery eyes, high fever, and spots inside the mouth.<\/p>\n But measles may also cause serious health complications, including pneumonia and encephalitis (inflammation in the brain), per the CDC.<\/p>\n Measles is considered one of the most contagious diseases in the world, according to the World Health Organization<\/a> (WHO). The virus can stay active and contagious in the air or on infected surfaces for up to two hours. The WHO also notes that one person who is infected with measles may infect up to 18 other people.<\/p>\n The virus spreads when an infected person coughs or sneezes, Dr. Russo explains. From there, people breathe in infectious particles or touch surfaces that those particles land on and then touch their eyes, nose, or mouth, which may lead to infection.<\/p>\n The infectious period with measles is long\u2014people who are infected may spread the virus to others four days before they develop the classic measles rash and four days after it appears, per the WHO.<\/p>\n How can I prevent getting measles?<\/p>\n There is a vaccine to prevent measles, called the measles, mumps, and rubella (MMR) vaccine. It\u2019s part of the childhood vaccination series and is given in two doses. One dose is 93% effective at preventing measles, while two doses is 97% effective, per the CDC<\/a>. (Despite new changes to the CDC’s childhood vaccination schedule, the MMR vaccine is still recommended<\/a> for all children.)<\/p>\n The first dose is usually given between 12 and 15 months, and the second dose is given between ages four and six, or whenever children start school, according to the American Academy of Pediatrics<\/a> (AAP). It\u2019s still possible to get the MMR vaccine as an adult or beyond that age range, but the doses need to be spread out by 28 days, per the AAP.<\/p>\n The MMR vaccine is a live attenuated vaccine, which means that it contains a weakened form of the measles virus, explains John Sellick, D.O.<\/a>, an infectious disease expert and professor of medicine at the State University of New York at Buffalo. That trains the immune system to react if you\u2019re exposed to measles down the road.<\/p>\n \u201cThe vaccine is not perfect, but it\u2019s really pretty good,\u201d Dr. Russo says.<\/p>\n (Just be aware that people born between 1963 and 1967 received a measles vaccine during childhood that isn\u2019t considered effective, according to the CDC. If this describes you, the CDC recommends<\/a> getting vaccinated again.)<\/p>\n Ultimately, you can get measles if you\u2019re fully vaccinated<\/a>, but it\u2019s unlikely. (Again, the vaccine is 97% effective, so three out of 100 vaccinated people<\/a> may get it.) \u201cThere were a few individuals who received a shot in the most recent measles outbreak and got infected,\u201d Dr. Russo says. \u201cBut if you have some protection, you\u2019re less likely to get severe disease as well.\u201d<\/p>\n What to do if you\u2019ve been exposed to measles<\/p>\n If you discover that you crossed paths with someone who has measles, don\u2019t panic. If you were born before 1957, doctors consider you to have \u201cpresumptive immunity<\/a>,\u201d which means that you were likely exposed to the virus as a child and therefore should have immunity to it, Dr. Russo says. \u201cIf you have presumptive immunity or if you\u2019ve been vaccinated, you don\u2019t have to worry about a measles exposure,\u201d he says.<\/p>\n