MIAMI — There’s a growing measles outbreak in the country and public health experts say vaccination is the best way to reduce the spread.

Measles is a highly contagious disease that can lead to serious complications, including pneumonia and brain swelling.

So far, more than 300 measles cases have been reported in the U.S. within the first few months of 2025, more than the confirmed cases reported in all of 2024, according to data from the U.S. Centers for Disease Control and Prevention.

The good news: The measles, mumps and rubella vaccine, or MMR, is just what the doctor ordered. One MMR dose is considered to be 93% effective against measles, with a second dose 97% effective, the CDC says.

And many people are already vaccinated. That’s because MMR is one of the mandatory vaccines needed for immigration into the U.S. and to become a resident. It’s also one of the required vaccines kids need to attend K-12 schools in Florida and other states. Students can avoid getting the shot for medical and religious reasons.

The CDC says it’s rare for people who are vaccinated against measles to get sick. Vaccination also helps protect those who can’t get the shot, including kids who are too young and people who are pregnant or have a weaker immune system due to an existing medical condition or medical treatment, said Dr. Marcos Mestre, chief medical officer for Nicklaus Children’s Hospital near South Miami.

People born before 1957 also lived through several years of measles epidemics, which means there’s a good chance they had measles at some point, public health experts say. If you’ve previously had measles, you should have immunity, too.

What if you’re not sure whether you’ve had the contagious disease before or if you received the MMR vaccine while growing up?

Here’s what to know:

Are there any measles cases in Florida?

The U.S. has confirmed at least 301 cases of measles across 15 states, with most of the cases reported in Texas, as of the CDC’s March 13 update. Florida has confirmed one case of the disease in a Miami-Dade County teen.

How to check your vaccination records in Florida

Besides asking your parents if they’ve kept copies of your immunization records, you can check your immunization history in Florida in several ways:

—Talk with your current and former doctors. They will likely have information on your immunization history in their records. But physicians aren’t required to keep your records forever. Under Florida law, physicians must maintain medical records for at least five years from the last patient contact.

Your health care provider will also likely have access to Florida SHOTS, a statewide and centralized system that tracks patient vaccination information. The system records immunization information for patients who get vaccinated at county health departments and from private providers who use the system. Pharmacists at retail pharmacies such as CVS and Walgreens will likely have access to this system, too.

But note that Florida is an “opt-out-state,” which means parents can choose to make their child’s records inaccessible in the system.

—If you attended a school in Florida, including a college or university, you can ask for your immunization records. However, schools aren’t required to keep this information forever, so your school may or may not have copies of your records.

—If you can’t find your records, contact your county’s local health department. Another option if you’re at least 18 is to fill out an online form to request your vaccination records directly from Florida SHOTS. You can only use this form to request your own personal records, not for another family member. You can’t use this form to request the vaccination history of minors. And remember, just because you fill out the form doesn’t guarantee the state will find your records in the system.

What if none of these options work?

You could talk with your doctor about scheduling a blood test to check for antibodies. But there’s another, cheaper option that may be easier:

Just get the MMR vaccine, according to Dr. Mary Jo Trepka, an epidemiologist at Florida International University in Miami-Dade County; Dr. Jill Roberts, an associate professor at the University of South Florida’s College of Public Health in Tampa; and Mestre, the Nicklaus Children’s doctor.

All three public health experts say it’s safe to get the MMR vaccine if you’re not sure whether you’ve previously been vaccinated or have had the disease.

“There’s really no harm to getting vaccinated again with the measles vaccine even if you’ve had it before,” Trepka told the Miami Herald last year when Florida reported a measles outbreak at a Broward elementary school.

If you got the MMR shot or measles as a child, do you need a booster?

The MMR vaccine isn’t like annual flu or COVID shots. It’s a two-dose vaccine meant to give protection for life. So, once you complete the two-dose series, you likely won’t need another shot, according to McClatchy News.

“It’s a live vaccine, meaning that it contains a small, weakened dose of the virus,” according to a Yale Medicine blog post. “This trains a healthy immune system to recognize the measles, mumps, or rubella viruses if one tries to invade the body, and attack it, preventing an infection from developing.”

What if you got the measles, mumps, rubella and varicella vaccine, or MMRV? Don’t worry. The CDC says that vaccine is also effective in giving life-long protections against measles.

Because the vaccines are highly effective in preventing infection, public health experts say it’s rare for vaccinated people to get sick and spread the disease. If they do get sick, it’s usually a mild infection, according to the CDC.

“Some vaccinated people may still get measles, mumps or rubella if they are exposed to the viruses,” the CDC says. “It could be that their immune system didn’t respond as well as they should have to the vaccine; their immune system’s ability to fight the infection decreased over time; or they have prolonged, close contact with someone who has the virus.”

Similarly, those who previously had a measles infection generally develop immunity against the disease and shouldn’t get sick again, public health experts say. Speak with your doctor if you have questions.

©2025 Miami Herald. Visit miamiherald.com. Distributed by Tribune Content Agency, LLC.