Measles Outbreaks Are Increasingly Common. Here’s What You Need to Know.

Lead

As of Feb 17, 2026, measles outbreaks are resurging across the United States and beyond, with a South Carolina cluster approaching 1,000 reported cases and infections now recorded in 20 states. Last year’s largest U.S. outbreak—762 cases in Texas—was the biggest annual total since 1991, and Canada has recently lost its measles elimination status. Public-health authorities say the situation is driven by gaps in vaccination coverage, and they urge full MMR immunization to prevent further spread.

Key Takeaways

• South Carolina’s current outbreak is approaching 1,000 reported cases, surpassing Texas’s 2025 outbreak that ended in August with 762 cases.
• Twenty U.S. states are reporting measles infections as of mid-February 2026; last year’s U.S. total was the highest since 1991 and included three deaths in 2025.
• The MMR vaccine (two doses) prevents infection in roughly 97% of recipients; about 3% of vaccinated people can have breakthrough infections, usually milder and less likely to transmit.
• Before routine vaccination, measles caused thousands of hospitalizations annually; elimination of continuous U.S. circulation was declared in 2000 but cases have occurred each year since.
• Herd immunity for measles requires about 95% vaccine coverage; small declines in coverage quickly enable outbreaks because measles is extremely contagious.
• People born 1957 or earlier are likely immune from past infection; those born 1957–1989 may have received less-effective vaccines and should consider a booster; people born after 1989 with two documented MMR doses are considered protected for life.
• Infants under 12 months are vulnerable; an early MMR dose at 6 months can be given for short-term protection but does not replace the two-dose schedule.

Background

Before the measles vaccine era, nearly every child contracted measles and the disease exacted a heavy toll: tens of thousands of hospitalizations and hundreds of deaths annually in the United States. A coordinated vaccination campaign interrupted continuous measles transmission and the U.S. achieved elimination of endemic measles circulation in 2000. That milestone did not mean zero cases forever; importations and localized outbreaks have occurred yearly since, usually controlled by high population immunity.

Measles is far more contagious than influenza or SARS-CoV-2. Because of that high transmissibility, population-level immunity must be very high—commonly cited near 95%—to prevent sustained spread. When coverage clusters drop below that threshold, even small introductions can seed large outbreaks, especially in communities with low access to care or concentrated vaccine hesitancy.

International patterns shape what happens domestically. Canada reported more than 5,000 cases recently and several European countries together recorded over 127,000 cases in 2024; those regional resurgences increase the risk of importations into the United States and complicate containment efforts.

Main Event

In early 2026 state health departments began reporting rapidly growing measles clusters. South Carolina’s tally climbed toward 1,000 cases, overtaking the prior year’s largest U.S. cluster in Texas, which finished with 762 cases in 2025. Health officials have linked spread to communities with suboptimal vaccination rates and to travel-related introductions from regions where measles is circulating.

Public-health responses include case investigations, contact tracing, expedited vaccine clinics, and targeted communication to affected communities. Officials emphasize timely administration of the two-dose MMR series for susceptible people and suggest early infant dosing or booster doses for specific exposure scenarios or travel.

At the federal level, discussions about vaccine policy have drawn attention. One reported recommendation from current White House advisers proposed separating the combined MMR vaccine into three individual shots for measles, mumps, and rubella. Public-health experts caution that splitting the shots offers no clear advantage in protection and could reduce overall uptake if it increases barriers or hesitancy.

Analysis & Implications

The immediate clinical risk is concentrated among the unvaccinated and very young infants. For unvaccinated people, measles carries substantial morbidity: about 20% of those infected require hospitalization, and some suffer long-term complications such as encephalitis or subacute sclerosing panencephalitis. That hospitalization rate underscores why current outbreaks have attracted urgent public-health action.

Breakthrough infections in fully vaccinated people are uncommon and typically milder. With two documented MMR doses, roughly 97% of recipients are protected against infection. Vaccinated individuals who do become infected have a lower likelihood of onward transmission, which helps blunt outbreak growth even when occasional cases occur in immunized populations.

Policy choices and access gaps matter. Research and outbreak reports suggest that access barriers, regional variability in public-health infrastructure, and local coverage shortfalls often explain transmission more than monolithic anti-vaccine sentiment. In some rural or underserved areas, logistical hurdles to vaccination can produce pockets of susceptibility that permit rapid spread when the virus is introduced.

Internationally, resurgent measles in multiple regions raises the baseline importation risk for all countries. That global context means that domestic elimination status can be fragile; maintaining high coverage, sustaining surveillance, and ensuring rapid response capacity are essential to prevent reestablishment of endemic transmission.

Comparison & Data

The table places current U.S. clusters in international perspective and reiterates key clinical and vaccination parameters. High vaccine effectiveness means that preventing cases remains largely achievable through standard immunization practices, while the hospitalization statistic illustrates the severe consequences when immunity gaps persist.

Reactions & Quotes

Measles remains one of the most infectious human viruses, and high two-dose coverage is our best defense against outbreaks.

Centers for Disease Control and Prevention (official)

We are prioritizing local vaccination clinics and public outreach to interrupt transmission and protect infants and immunocompromised residents.

State health official, South Carolina Department of Health (state public-health agency)

Separating MMR into three shots is unlikely to improve immunity and may introduce logistical barriers that lower overall vaccination rates.

Independent infectious-disease specialist (academic)

Unconfirmed

• Whether splitting the MMR vaccine into three separate shots will be formally adopted as federal policy and what measurable impact it would have on coverage remain unconfirmed.
• Precise drivers of specific local outbreaks vary by community; in some cases the balance between access issues and intentional refusal is still under investigation.
• Long-term national trends—whether current increases will produce sustained endemic transmission in the U.S.—are uncertain and depend on vaccination responses in the coming months.

Bottom Line

Measles poses a renewed public-health challenge in 2026 because immunity gaps and international circulation have combined to produce larger, faster-moving outbreaks than seen in recent years. The disease’s high transmissibility and meaningful hospitalization rate for unvaccinated people make prevention through vaccination the central priority.

For individuals: confirm two documented MMR doses for yourself and your household, consider early infant dosing or expedited second doses when travel or local outbreaks present elevated risk, and ensure close contacts are immunized to protect those who cannot be vaccinated. For policymakers: maintaining vaccine access, clear communication, and rapid outbreak response will determine whether these clusters remain controllable or escalate.

Sources

• Slate — explanatory report (media)
• Centers for Disease Control and Prevention — measles information (U.S. public health)
• World Health Organization — measles factsheet (international public health)
• Public Health Agency of Canada — immunization and case reports (Canadian public health)
• South Carolina Department of Health — outbreak updates (state public health)