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Measles outbreaks are on the rise across the United States, particularly in regions where vaccination rates are low.

Last year, the US reported 285 measles cases, marking the highest number since 2019, as noted by the US Centers for Disease Control and Prevention. In just the first few weeks of 2025, two cases were confirmed in metro Atlanta, followed by a confirmed case in New Mexico, and a growing outbreak in West Texas, which currently has 24 reported cases, according to the state health authorities. Additionally, cases have emerged in Alaska, Rhode Island, and New York City.

Measles is an extremely contagious airborne virus that leads to symptoms such as rash, fever, red eyes, and cough. Serious complications can arise, including blindness, pneumonia, or encephalitis, which is the swelling of the brain, as per the World Health Organization. In severe instances, measles can be fatal.

Before the measles vaccine was introduced in 1963, approximately 2.6 million deaths from the virus occurred globally each year. In 2023, the WHO estimated there were 107,500 deaths due to measles, mainly in countries with poor vaccination coverage.

“People have forgotten the severity of measles. Many may not realize how devastating it can be,” stated Dr. Paul Offit, who leads the Vaccine Education Program at the Children’s Hospital of Philadelphia.

Experts recommend that everyone reevaluate their immunity to measles, especially in light of current events.

According to specialists, vaccination is the most effective method to protect against measles. The measles, mumps, and rubella (MMR) vaccine boasts a 93% efficacy rate against measles after one dose, increasing to 97% after two doses, as confirmed by the CDC.

Guidance from health authorities recommends that children receive two doses of the MMR vaccine, with the first dose administered between 12 and 15 months and the second dose given around age 4, prior to entering school.

“When parents make decisions about vaccinating their children, it’s important to remember that it affects not just their child but the entire community’s health. If we neglect the health of the population, we risk more outbreaks of vaccine-preventable diseases,” expressed Dr. Christina Johns, a pediatric emergency physician at PM Pediatrics.

Older children and adults who missed vaccinations in childhood can still receive the vaccine, according to Johns. However, those born before 1957 are likely to have immunity due to prior natural infections, as indicated by the CDC.

The CDC’s guidance also states that individuals exposed to measles should receive the MMR vaccine within 72 hours to possibly gain some protection or reduce the severity of symptoms.

Nationwide, the uptick in measles cases is largely attributed to declining vaccination rates, as noted by Johns, who attributes this decline to “the widespread misinformation and disinformation regarding vaccines.”

A recent report indicated that a record number of kindergarteners in the U.S. received exemptions from mandatory vaccinations last school year, resulting in over 125,000 new school attendees lacking at least one required vaccine, according to data published by the CDC in October.

The US Department of Health and Human Services has set an objective for at least 95% of kindergarteners to have received two doses of the MMR vaccine, a critical threshold needed to prevent outbreaks of this highly infectious disease. However, the U.S. has failed to meet this benchmark for four consecutive years.

Titer tests available at primary care facilities can assess immunity to measles. Experts advise that these tests may not be necessary for individuals who have received both doses of the MMR vaccine or have previously contracted the disease.

Titer tests measure the presence of antibodies, which are proteins produced by the immune system in response to infections. After vaccination or an infection, immune cells learn to produce these antibodies, which can remain in the body for years, providing defense against future infections.

Because measles has a longer incubation period, the body has an extended timeframe to build an immune response, allowing for more antibody production. Therefore, even if titer tests show low antibody levels, memory cells may still respond effectively to the measles virus, according to Offit.

“What’s essential is having that immune memory,” he explained, noting that this is typically not assessed in commercial laboratories.

Titer tests are especially beneficial for individuals unsure of their vaccination status, experts remark.

This uncertainty often arises when individuals lack access to their vaccination records due to relocation, changes in pediatric practices, or the retirement or passing of healthcare providers, noted Dr. William Schaffner, an infectious disease specialist at Vanderbilt University Medical Center.

Physicians may also consider testing patients with compromised immune systems to determine their measles immunity level. In such cases, patients may not be suitable candidates for the vaccine, which utilizes a live but weakened form of the virus, but they may still desire clarification on their immunity status and further discussion with healthcare providers.

If you received the initial version of the measles vaccine—a killed-virus vaccine used from 1963 to 1968—or are unsure about the type of vaccine administered, the CDC recommends receiving at least one dose of the MMR vaccine.

Experts agree that individuals who received two doses of the current MMR vaccine are likely to have lifelong immunity against measles.

“Less than 1% of fully vaccinated individuals may experience waning immunity to measles that could leave them vulnerable to infection,” Johns stated. “While immunity can decrease with age, those who are thoroughly vaccinated are generally considered protected for their entire lives.”

During mumps outbreaks, health authorities may recommend that high-risk populations receive additional doses of the MMR vaccine, according to the CDC.

In terms of measles, Schaffner notes that some individuals may have low antibody titers after testing. In these instances, “with guidance from their healthcare providers, they may opt for an additional vaccine booster. While there’s typically no harm in doing so, the benefits may be uncertain.”