South Carolina Measles Outbreak Is One of the Largest in Decades

There are certain diseases many of us quietly filed away as solved. Measles was one of them… until headlines like this yank it right back into the group chat. Experts warned that a multi-state measles outbreak in December was the largest the U.S. had seen in decades. Now, just a few months later, South Carolina is facing an outbreak that’s approaching 1,000 cases, and it’s again being described as the biggest since the early 1990s. Here’s what we know, why this is happening, and what families can do right now.

2026 Measles Outbreak in South Carolina

According to a recent article from Reuters, South Carolina officials are seeking additional reinforcements (including non-CDC public health support) as they work to contain the rapidly growing outbreak. The case count is nearing 1,000, straining local health systems and prompting renewed concern about vaccination coverage in affected communities.

State officials have described the outbreak as one of the largest the U.S. has seen since 1992. (It’s worth noting that another outbreak earlier this winter was also labeled “the largest since 1992,” which speaks less to headline inflation and more to how unusual — and alarming — these case numbers are in the post-vaccine era.)

For broader context, the Centers for Disease Control and Prevention tracks measles cases nationwide. In recent years, the U.S. has seen spikes tied to pockets of low vaccination coverage, but outbreaks approaching this scale remain rare. You can follow updated national case counts on the CDC’s measles surveillance page. We’ve also previously reported on multi-state measles activity and what it means for families, as well as how childhood vaccine recommendations are developed and updated.

Why Are We Seeing Larger Outbreaks Again?

Dr. Sharon Nachman, chief of pediatric infectious diseases at Stony Brook Children’s Hospital, says the story of measles is really a story about how contagious a virus can be, and what happens when vaccination rates dip.

“Each illness has its own storybook,” she explains. “How infectious it is from person to person — via air, droplets, or on surfaces — how long it can linger, and how contagious someone is after they become sick.”

Measles is, unfortunately, one of the most contagious viruses we know.

It can spread through the air up to 40 feet and linger in a closed room for up to two hours after an infected person leaves. There is no natural immunity in people who haven’t had the disease or been vaccinated, meaning if you’re exposed and unprotected, you are very likely to become ill.

“When vaccination rates dip below about 85%, the population is at risk,” Nachman points out.

That threshold matters because measles relies on opportunity. In communities where vaccine coverage falls — whether due to access issues, hesitancy, or misinformation — outbreaks can ignite quickly and spread before they’re detected.

How Vaccine Recommendations Are Actually Made

If you’ve ever wondered who decides when and how vaccines are added to the pediatric schedule, Dr. Nachman says the process has historically been rigorous and transparent.

In the past, vaccines were only added to the Advisory Committee on Immunization Practices (ACIP) and CDC schedule after extensive review. That includes data from at least two Phase 3 clinical trials, safety and efficacy analyses, an independent FDA review, and input from stakeholders such as the American Academy of Pediatrics and the Infectious Diseases Society of America.

Event rates (including illness counts per 100,000 people, hospital visits, emergency department admissions, and deaths) are publicly presented and discussed before recommendations are finalized. Presenters must also disclose any conflicts of interest.

That process is designed to ensure vaccines are added based on evidence, not politics or pressure.

For parents looking for reliable information, Nachman recommends starting with the AAP, reviewing state-level illness data, and consulting resources like CIDRAP’s VaxIntegrity Project, which tracks vaccine policy and public health data.

Common Vaccine Myths and Facts

In the middle of an outbreak, misinformation spreads almost as quickly as the virus itself. Nachman says some of the most common misconceptions include:

“Vaccines were never tested in kids.” They were. Pediatric vaccines undergo clinical trials in children and typically require two Phase 3 trials for FDA licensure.

“Safety wasn’t evaluated long-term.” The National Academy of Medicine has conducted and published multiple long-term safety reviews.

“We don’t even have measles here anymore.” State health departments and the CDC publish case rates annually, and outbreaks like this one show that measles is still very much a threat when vaccination coverage drops.

“Vaccines contain dangerous ingredients.” Thimerosal, a mercury-containing preservative, has not been used in pediatric vaccines since 2001 and was never used in the MMR (measles, mumps, and rubella) vaccine, per the CDC. Aluminum is not used in live viral vaccines such as MMR, varicella, or rotavirus.

These aren’t new myths, but in moments like this, they often resurface louder, so we wanted to bring it up here for a swift reality check.

What Parents Can Do Right Now

Whether you’re in South Carolina or not, it’s important to take the necessary precautions. First and foremost, check your child’s vaccination record. The MMR vaccine (measles, mumps, rubella) is typically given in two doses: the first at 12 to 15 months and the second at 4 to 6 years. If your child has fallen behind, don’t panic. There are established catch-up schedules outlining what to give and the interval between doses.

Nachman emphasizes that pediatricians have carefully written plans for children who are behind, immunocompromised, or on immune-suppressing medications. If your child has special medical considerations (such as cancer treatment or recent immune globulin therapy), talk directly with their pediatrician about timing.

If you’re unsure where to start, the AAP and your state health department website are good first stops.

How To Talk to Other Parents and Your Kids

Measles outbreaks don’t just raise medical questions — they create social tension. When talking to other parents about vaccines, Nachman recommends leaning on trusted sources rather than social media debates. Share information from organizations like the AAP or CDC instead of engaging in back-and-forth arguments with trolls you don’t know (plus, those you do).

With kids, keep it simple and age-appropriate. There are children’s books — like Lily Llama Helps Her Herd and Sophie Gets Her Shot — that walk young readers through what vaccines are and why they matter. Many frame it as a way to protect not just yourself, but your community.

Remember, measles is not just an individual risk. It’s a community risk. When vaccination rates fall, outbreaks grow. As South Carolina works to contain nearly 1,000 cases, public health officials are racing to do what vaccines have done quietly and effectively for decades: stop a virus in its tracks.

For parents watching from home, the most powerful step is also the simplest: making sure your family is protected, and helping keep your community that way, too.