Do adults need a measles booster? Epidemiologists explain who is immune

The outbreak of measles that began in Texas in late January continues to grow. As of March 27, 2025, the number of confirmed cases across the United States reached 483, exceeding the total number of confirmed cases recorded in 2024. Approximately 93% of cases are associated with outbreaks. It currently spans Texas, New Mexico and Oklahoma.

clock: What lies behind the growing measles outbreak and how the Trump administration responds

Most cases It's for people who haven't been vaccinated. meanwhile, Lack of clarity from health authorities It leaves people with questions about whether they need to be reacting.

Q&A with conversation, Daniel Pastaraneurologists and medical epidemiologists at the University of Colorado Anschutz Medical Campus and the Colorado School of Public Health, explained how and when you should take action.

Should adults get another shot of the measles vaccine?

Measles vaccine is the first It was made available in the US in 1963contains strains that are live-resistant but have become significantly weaker than measles virus. This modified strain is too weak to cause measles; It is similar enough to the wild type measles virus Train and recognize the immune system. Most people who have received the live measles vaccine don't need additional shots right now, but here's what you need to know.

Those born before 1957 are It is estimated that you have lifelong immunity Because measles was very contagious Almost everyone signed it by the age of 15.. Unless there is a special situation, they probably don't need the vaccine at the moment.

Most people born after 1957 received shots as children, so they should be ready for life. Doctors and public health experts Most people in this group do not recommend getting a second measles shotthough there are exceptions.

Limited outbreaks of measles in 1989 It occurred among vaccinated school children. In response, Recommendations have been changed from one dose Up to two doses for children of the live measles vaccine. Since that year, people have been fully vaccinated as children No additional dose required.

Graphics by Steff Staples/PBS News

Exceptions to these guidelines

There are two special circumstances in which previous recommendations may not be retained.

First, if you were vaccinated between 1963 and 1967, one of the measles vaccines available at the time consisted only of proteins from the virus, not a weaker version. Researchers quickly noticed this Inactivated or “killed” vaccines were not very effective It did not provide long-term immunity. Unless you identify that you received a live vaccine, doctors and public health experts recommend that people get the vaccine that year Get one dose of live vaccine At some point.

Secondly, if you fall into a high-risk group – for example, if you are a healthcare provider, travel internationally, or attend university, doctors, public health professionals, generally I recommend getting a second dose If you only have one.

Graphics by Steff Staples/PBS News

For most adults without such risk factors, physicians and public health experts Do not recommend a second dose regularly If you have received one live measles vaccine before. If you have any questions or concerns about your situation, be sure to ask your health care provider.

Except in very rare circumstances, there are no recommendations for a third dose of the measles vaccine.

Can I know if I've been vaccinated?

Maybe it can! It's worth checking out. The state actually keeps a vaccine record Specifically, this allows us to look at vaccine records and child records. Your high school or university may still have your records, and so may your pediatrician's office.

Do I need to check my antibody levels?

For most people, that's probably not the case.

Titer Test Check the level of antibodies in the bloodand some people are asking doctors to check their titers to determine if they are still immune to measles. The problem is that the levels of antibodies in the blood do not necessarily reflect your immune level. That's because antibodies are Part of the immune system's infection fighting power. Low levels of antibodies do not necessarily mean that your immunity has declined.

Other important elements of the immune response are included B cells, T cells and other immune cellshowever, titer tests do not show its function. For example, memory B cells may not currently produce antibodies to the virus, but are prepared to do so immediately the next time you see it. This is why you should consult with your doctor and use antibody and titer tests only in certain cases.

Graphics by Steff Staples/PBS News

One example of when an antibody test is required is if you are a healthcare provider born before 1957 and want to make sure you don't need another dose of the vaccine. Use the test to see if there are any measles antibodies. But in this case you are looking for the answer yes or no. The total amount of antibodies may not be very beneficial.

Is innate immunity better than vaccine-induced immunity?

Innate immunity, that is, the immunity obtained after eating measles, is effective. However, the drawback is that natural infections from wild viruses are extremely dangerous. Before 1963, measles was caused Children typically have around 500 hospitalizations and around 500 deaths each year in the United States. It also caused more than 1,000 severe encephalopathy each year, carrying several other long-term risks, including permanent hearing loss and wiping immunity to other diseases.

read more: What you need to know about highly contagious measles and how to protect yourself

The key to vaccines is to create immunity without the risk of severe infection. It's basically a dress rehearsal for the real thing. Immunity from a vaccine is virtually the same as the immunity you get from having measles itself, but it's much safer than encountering an unprotected wild virus. One dose is 93% effective in preventing measles Two doses are 97% effectiveand the groundbreaking case could be much milder than the full-fledged case of measles.

Can the vaccine cause measles?

No, measles vaccines cannot cause measles. Limited ability to infect and damage cells.

Some claim without proof of current evidence The outbreak in Texas was caused by the measles vaccine.

read more: Measles cases are rising in the US, which is why misinformation about today's vaccines continues today

However, as part of an outbreak investigation, the CDC and the Texas Department of State Health Department analyzed the genome of the virus causing the current outbreak and identified it as a wild measles virus. Researchers classify measles virus strains Based on genetic characteristics or genotype. They identified Developmental virus as wild-type genotype D8and not a weakened measles vaccine strain, but a genotype A.

https://www.youtube.com/watch?v=gzx28d6i8ai
Measles vaccinations work so well that many people today have never seen cases of measles.

What are the risks of vaccines?

That's a very reasonable question. Measles vaccines are live, weak virus strains, which can cause mild measles-like syndromes. For example, some people may have slight fever, rash, or slight joint pain. These symptoms generally go away in a day or two, and most people do not experience them. However, vaccines cannot cause measles per se. Because it does not contain the wild measles virus.

In very rare cases, people can experience it More important responses to the measles vaccine. It is important to remember that all medical or health interventions have risks. This includes all drugs and over-the-counter supplements. However, according to all available evidence, when comparing the potential benefits with the potential risk, The risk of a major reaction For vaccines Much lower than the risk of serious consequences from measles itself.

Having vaccinated not only protects you and your family, Protect vulnerable people in our communityinfants, cancer patients, pregnant women, etc., cannot vaccinate themselves.

This article has been republished conversation Under the Creative Commons license. Please read Original article.