Are You Immune to Measles?

With cases rising in North Carolina and South Carolina, public health leaders stress that vaccination is highly effective but not perfect.

As measles cases increase across the Carolinas, public health officials are urging residents to check their immunity status and understand what protection vaccination does — and does not — provide.

According to the North Carolina Department of Health and Human Services, immunity to measles depends on age, medical history, and vaccination records. While the measles, mumps, and rubella (MMR) vaccine offers strong protection, it is not 100 percent effective.

The Centers for Disease Control and Prevention reports that:

• Two doses of MMR are about 97% effective at preventing measles

• One dose is about 93% effective

  
  

That means even fully vaccinated individuals still have a small — roughly 3% — chance of getting measles, particularly during outbreaks when the virus is circulating widely. Health officials say these so-called “breakthrough cases” are uncommon and typically milder than infections in unvaccinated people.

Who is considered immune?

Under current CDC guidance, a person is generally considered immune to measles if they meet at least one of the following criteria:

• Born before 1957

• Have documentation of two doses of a live measles-containing vaccine (such as MMR)

• Have a laboratory-confirmed positive measles antibody titer

• Have documented evidence of past measles infection

Most adults need at least one documented dose of MMR to be considered immune, but health officials recommend two doses for stronger protection, especially for health care workers, students, and people traveling internationally.

Why vaccinated people can still get measles

CDC officials say breakthrough infections can occur because no vaccine provides absolute protection. The risk increases in communities with lower vaccination coverage, where measles can spread rapidly and expose people to high levels of virus.

Despite that small risk, vaccination dramatically reduces the chances of severe illness. Nearly all recent measles cases nationwide have occurred in people who were unvaccinated or whose vaccination status was unknown.

What to do if you’re unsure

NCDHHS offers a self-guided measles immunity questionnaire to help residents determine whether they are considered immune and what steps to take next. Officials stress that the tool is for education only and does not replace advice from a health care provider.

Anyone who believes they were exposed to measles should call their doctor or local health department immediately before going in for care. In some cases, vaccination within three days of exposure can prevent illness or reduce severity.

Why health officials remain concerned

Measles is one of the most contagious viruses known. It spreads through the air, can linger for up to two hours after an infected person leaves a room, and can be transmitted before symptoms appear.

Complications can include pneumonia, brain inflammation, and, in rare cases, death — particularly among infants, young children, and pregnant women.

Public health officials emphasize that while vaccination does not eliminate 100% risk, it remains the most effective tool to prevent measles and limit outbreaks.

“Even with a small chance of infection, vaccinated people are far better protected,” the CDC website said. “High vaccination coverage is what keeps measles from spreading widely in our communities.”