A conversation with Dr. Paul Cieslak, medical director for communicable diseases and immunizations at Oregon Health Authority
The measles vaccine is a true public health success story. Before it was introduced in 1963, nearly every child in the United States got measles. Globally, major measles epidemics occurred approximately every two to three years and killed an estimated 2.6 million people each year.
But with widespread measles vaccination after 1963, childhood measles cases plummeted quickly. It’s estimated that the measles vaccine has saved 94 million lives worldwide over the past 50 years. In 2000, measles was declared “eliminated” in the United States—meaning that transmission had been stopped.
But measles vaccination rates in Oregon and across the U.S. are not as high as they once were, which is why we’re seeing more outbreaks. With such a contagious virus, the risk of an outbreak turning into a widespread public health problem is not out of the realm of possibility.
Children under age 5 are the most vulnerable to measles. During 2024 and 2025 so far, children under 5 have accounted for about 38% of all measles cases in the U.S., and about 40% of those hospitalized, according to the Centers for Disease Control and Prevention (CDC).
The measles vaccine is a two-dose vaccine routinely given to children. The CDC recommends the first dose be given between ages 12-15 months, and the second between ages 4 and 6. After two doses, a person is considered immune from measles for the rest of their life.
In order to help Oregonians understand their risk and to provide information about the measles vaccine, we asked a series of common questions to Paul Cieslak, medical director for OHA’s communicable diseases and immunizations division.
Q: How does someone catch measles, and how dangerous is it?
Measles is perhaps the most contagious virus in the world. It spreads swiftly via the “airborne” route, which means that people who aren’t protected can get it merely by breathing the air that someone with measles has coughed into or even exhaled. After exposure, the virus takes about 7-10 days to cause initial symptoms that most people will blame on a simple cold or other respiratory virus: fever, cough, nasal congestion and red eyes. A few days after that, however, the rash starts, which is usually when someone realizes something else is going on. But people are contagious as early as four days before the rash begins to appear, and for up to four days after it begins to appear. (The rash is neither itchy nor painful.)
For most, symptoms will resolve within a few weeks at home. In developed countries in recent years, about 20% of measles cases have been hospitalized, though in 2024 in the U.S., 40% of all measles cases were hospitalized. Approximately 1-2 of every thousand have died.
Measles is especially dangerous for children. About 1 in 20 children with measles will develop pneumonia and may have to be hospitalized. About 1 in 1,000 children get encephalitis (brain swelling), which can do permanent damage—deafness, blindness, intellectual disability, and rarely, death.
Research shows measles can also cause “immune amnesia,” which means a person’s immune system “forgets” how to fight off other diseases they may have previously been somewhat or totally immune to due to vaccination or infection (e.g., mpox, polio, HPV, chicken pox, tetanus, COVID-19, etc.). This can leave a person who survives measles with a significantly weakened immune system, for a period of time that could last years, when it comes to certain health risks.
Learn more about measles risk, symptoms and complications here.
Q: What is the measles vaccine? Is it safe?
Today’s measles vaccine comes in a combo shot called the MMR vaccine, which protects people against measles, mumps and rubella; protection is for life against measles and rubella (aka German measles or “three-day measles”), but some people do get mumps despite vaccination. Getting this combination shot is safe and saves you a couple of extra shots. Side effects include the usual sore or red arms, and some people get a short-lived fever. About 5% of people will get a rash that they may mistake for measles – but it’s mild and doesn’t come with the complications of a real case of measles.
After getting vaccinated, it takes about two weeks for a person to be fully protected.
After the measles vaccine first became available to the public in 1963, a mumps vaccine was introduced in 1967, and a rubella vaccine in 1969. The three vaccines were combined into the MMR vaccine in 1971. Learn more about the history of the MMR vaccine here.
Q: How do I know if I need a measles vaccine, and why do I keep hearing that I don’t need it if I was born before 1957?
People born before 1957 do not need to be vaccinated against measles because they’re presumed to be immune. That’s because, before the measles vaccine was first available to the public in 1963, virtually all children would get measles by their teenage years, and survivors are immune for life. People born in 1957 or shortly thereafter, however, could still benefit from the vaccine because they would have been—at most—6 years old in 1963. At that age, there was still a meaningful chance they hadn’t been exposed to measles yet and could benefit from the new vaccine.
Q: I’ve heard that earlier versions of the measles vaccine weren’t very effective. Is that true? If so, how do I know what version I got, and can I get vaccinated now just to be extra cautious?
During 1963 to 1968, two versions of the measles vaccine were available. One was a “killed” vaccine, which used an inactive and weakened version of the measles virus. The immunity people got from that version waned after several years, and it was discontinued in 1968. Approximately 600,000 – 900,000 people in the U.S. received that version, which is a very small portion of the current population. If someone knows that they received that version, they would benefit from one dose of the MMR vaccine. Or, if someone simply doesn’t know which version they received, or they believe they may have had measles as a child but aren’t sure, it is perfectly safe to get vaccinated against the measles now just in case. We recommend people discuss these scenarios with their provider first.
The other original (and more successful) measles vaccine was a “live” vaccine, which used an active and even more weakened version of the measles virus. People vaccinated with two doses of that version are immune for life and do not need to be revaccinated. Today’s MMR vaccine uses this technology.
Few people still have their original, paper measles vaccination records from that era, but if they do, they can show it to their provider who can help them understand which version they received, if any. The U.S. Department of Defense and U.S. Department of Veteran’s Affairs also keep vaccination records for military members.
Q: Is everybody required to be vaccinated against measles?
Not all, but most. Oregon law requires all children attending public or private schools (preschool through 12th grade), Head Start programs or certified childcare facilities to receive two doses of MMR vaccine. If a child enters school or daycare before they’ve received the second dose, they can receive the second dose earlier (as long as it’s been at least 28 days since the first dose). They can also receive an MMR dose as young as 6 months old if they live in or are traveling to locations where a measles outbreak is happening – but any dose given before 1 year of age does not count toward the 2-dose regimen. Parents should discuss these scenarios with their pediatrician.
The law does allow parents to claim exemptions to the requirement for medical or nonmedical reasons; but even with an exemption, students exposed to measles will be sent home until 21 days after the onset of rash in the last person who exposed them. You can read the law here.
Also, older students enrolled full-time in post-secondary educational institutions (e.g., colleges or universities) must provide proof of measles vaccination (two doses). The law applies to community colleges as well, but only for students participating in clinical experiences or education, or childcare programs. The law allows for exemptions in these situations as well.
Certain professions also require proof of measles vaccination, including health care and food service workers. This proof, as well as proof for education purposes, can also be done with a blood test that measures one’s immunity to measles (see next question).
Q: Is there a test I can take to find out if I am immune from measles?
Yes, there is a simple blood test that can tell if you’re immune: it’s called a measles “titer” test, and it detects measles antibodies in the blood. You can ask your health care provider about this, or have your blood tested at a pharmacy or public laboratory (call ahead to confirm). Insurance plans may cover the cost of titer testing, possibly with some cost-sharing; we advise calling insurers in advance to confirm.
Titer testing can be useful if you need to prove your vaccination or immunity status for a job or education, if you’ve been exposed to measles (or heading to an area where you might be exposed) and are curious about your status, or if you were born during or after 1957 and are unsure about your history of measles and vaccination.
But again, if you were born before 1957, had the measles, or received two doses of measles vaccine, consider yourself immune and look no further.
Q: Where can I find my measles vaccination record?
People in Oregon can access their vaccination records in a couple ways. One is through their health care provider. The other is to contact the help desk of Oregon’s “ALERT” Immunization Information System (ALERT IIS) at 800-980-9431 or alertiis@odhsoha.oregon.gov. For more information, visit our Getting Immunization Records webpage.
ALERT IIS may not have your childhood vaccination records if you were born before 1996 or were vaccinated in another state or country. You can request your records for whichever state you were vaccinated. Find contact information for each state here.
If you have a record of your childhood vaccinations and would like them recorded in ALERT IIS, please give it to your medical provider on your next visit and request that they enter it into ALERT IIS. This includes the old vaccination cards or booklets that were used back in the day, which providers updated by hand with each new vaccination given. Some older folks (or parents!) may still have these.
Q: If we’re seeing a rise in measles cases because fewer people are getting the MMR vaccine, why aren’t we seeing a similar rise in mumps or rubella cases?
Since the year 2000, we really see measles in the U.S. only when someone brings it in from another country where it is more common – and then it may spread here for a period of time. The same is true of rubella – but rubella is not nearly as contagious as measles, and it was last seen in the Americas in 2009. We do see mumps regularly in the U.S., because the MMR vaccine doesn’t provide as high a level of protection as it does for measles: During 2024, 357 mumps cases were reported nationwide, with 6 in Oregon, compared to 285 measles cases nationwide and 31 in Oregon.
Q: What does “herd immunity” mean, and does Oregon have it?
“Herd immunity” (also known as “community immunity”) is when so many people are immune to a disease that the disease can’t find enough susceptible people to keep spreading: so even non-immune people are protected, because there are so few people who could even expose them. Because measles is so highly contagious, however, a very high percentage of people need to be immune for us to have “herd immunity” — about 93%. Oregon is right on the cusp of that. So if our immunization rate falls much further, we could see no end to the transmission.
Q: What should I do if I think I may have been exposed to measles?
If you’re immune – that is, born before 1957, have had the measles, or have had two doses of measles vaccine – you have nothing to worry about. But if not—if you are unvaccinated and have never had the measles – get vaccinated right away. If you get vaccinated within three days of being exposed, you have a good chance of avoiding infection. But if you are exposed and pregnant or immunocompromised (or for exposed infants under 6 months old), we recommend asking your doctor or pediatrician about getting immune globulin (IG)—an injection that should be administered within six days of exposure.
Q: Does vitamin A help protect against measles?
Vitamin A does not protect someone from catching measles. The CDC recommends that children with measles severe enough to be hospitalized be given vitamin A. This vitamin has protective effects on the eyes, and measles can cause blindness when it strikes someone with insufficient levels of vitamin A. People can have low vitamin A for a few reasons: they are infants or young children, pregnant or breastfeeding, or have certain conditions that limit the body’s ability to absorb vitamin A. Also, having measles can reduce your level of vitamin A.
Learn more about vitamin A deficiency here.
Where to get the MMR vaccine in Oregon
People can receive the MMR vaccine at their next visit with their health care provider (including pediatricians), at their local pharmacy, county health department or many local community clinics. Although most Oregon pharmacies stock the MMR vaccine, they can administer it only to children who are at least 7 years old (and adults). Call pharmacies in advance to confirm.
Oregon students can also get the MMR and other vaccines at School-Based Health Centers (SBHC), which serve children and youth even if they don’t have insurance or can’t pay. SBHCs can bill Oregon Health Plan (OHP/Medicaid) and often bill other insurance. There are 87 certified SBHCs in 28 Oregon counties, and some serve siblings, families and community members as well. See this list of Oregon’s SBHCs, and contact the school or medical sponsor for details.
The CDC’s Vaccines For Children program provides no-cost vaccinations for eligible people under age 19. Search for VFC providers near you here.
Also, this easy-to-use health center search tool shows federally funded clinics that serve people without insurance or a regular source of health care.