Measles Transmission by Vaccinated People Documented in Medical Literature

A new systematic review and meta-analysis published in the peer reviewed medical literature confirmed that people who have received measles-containing vaccines can become infected with measles and transmit the infection to others, contributing to measles outbreaks around the world. The study, which was published Aug. 14, 2026 in Expert Review of Vaccines, screened 5,240 peer-reviewed records in the medical literature, as well as evidence from gray literature records.¹

Gray literature refers to information, which is unpublished or only available through specialized channels, such as public health agencies, private labs or other entities. Usually, gray literature has not been published in academic medical journals or other publications by commercial publishers.²

The researchers ultimately included 33 studies and reports related to cases of measles transmission in the review and analysis. Among the 890 vaccinated measles cases represented in the included studies, 70 (7.9 percent) transmitted measles to others, producing 237 direct secondary cases. Additionally, 22 of the 70 transmitters (31.4 percent) had received two or more doses of measles-containing vaccine (including some who had received three doses).³

One study that used measles case surveillance data in the Netherlands compared MMR vaccinated cases that transmitted measles compared to vaccinated cases that did not. Most of the cases of measles were transmitted by vaccinated individuals who had received only one dose of MMR vaccine. Vaccine effectiveness against “measels infectiousness” was found to be 10 percent for one dose of vaccine and 61 percent for at least two doses of MMR vaccine.

The finding is notable given that the U.S. Centers for Disease Control and Prevention (CDC) says two doses should “protect people for life against measles” and that two doses are more effective against measles than one dose,⁴ adding that the second dose may provide more immunity for those who do not respond to the first dose. The CDC states on its website “Of those who do not respond to the first dose of the measles component of MMR or varicella vaccine, 97%–99% respond to a second dose.”⁵

Measles Transmission by MMR Vaccinated Individuals Documented in 18 Countries

Transmission of measles by people who had received MMR vaccine was documented in 18 countries, including countries where measles is considered to be endemic, but also in countries where public health officials considered transmission interrupted or declared measles transmission had been eliminated by high uptake of MMR vaccine. Measles transmission by vaccinated persons was found to have occurred in health care facilities, schools, and community settings, including some reported exposures involving brief encounters or no direct contact at all.⁶

“Transmissions occurred in healthcare facilities, schools, and various community settings, where children who are not vaccinated or immunocompromised individuals may be focused, potentially raising the risk of transmission,” the study states.

Measles transmissions from vaccinated cases, although relatively uncommon, must be considered in public health investigations, as such transmissions can contribute to outbreaks.⁷

Despite 35-Year High in Measles Cases, Measles Deaths Remain Rare in U.S.

According to mainstream media reports, measles cases have climbed in the U.S. in recent years, reaching a 35-year high in 2026.⁸ The CDC states that one to three of every 1,000 children who become infected with measles will die from respiratory or neurologic complications.⁹ However, the CDC’s own surveillance data shows a lower mortality rate among reported U.S. measles cases across all age groups in recent decades.¹⁰

According to the CDC, among 4,056 measles cases reported in the United States between 2001 and 2022, three deaths were reported, amounting to approximately 0.74 deaths per 1,000 reported measles cases across all age groups during the 22-year period.¹¹ Twelve years passed between 2003 and 2015 without a single reported measles death. According to news reports, the adult woman who died with measles in 2015 had underlying health conditions and a suppressed immune system due to medications she was taking.¹²

There were no reported U.S. measles deaths between 2016 and 2024, followed by three reported deaths in 2025. As of Sept. 4, 2026, the CDC stated that the National Center for Health Statistics (NCHS) “does not currently have any death records from 2026 that indicate measles is the underlying cause.¹³

CDC Measles Data Groups Unvaccinated Cases with Unknown Vaccination Status

Mainstream media outlets historically have blamed measles outbreaks on unvaccinated individuals. However, the CDC’s public reporting of measles cases and outbreaks combines cases reported as unvaccinated with cases for which “vaccination status is unknown.” An “unknown” vaccination status does not mean a person was unvaccinated.

Combining the “unvaccinated” and “unknown vaccination status” categories, therefore, does not confirm the number of measles cases occurring among unvaccinated people. Reporting of measles case information is misleading and skews public perception when the combined figure is repeated in the media without specifying what proportion of cases had an unknown vaccination history. Thus, the combined “unvaccinated or unknown” figure alone cannot reliably support claims that measles outbreaks are occurring exclusively among, or are exclusively attributable to, unvaccinated people.¹⁴

“Whenever the Public Health Empire gets worried that people are losing their fear of contagion, suddenly cases of an infectious disease pop up and we are told that unless everyone gets vaccinated, death is only a sneeze at the check-out counter or a plane ride away,” said National Vaccine Information Center (NVIC) co-founder and president Barbara Loe Fisher, a longtime vaccine safety and informed consent advocate and co-author of the 1985 book DPT: A Shot in the Dark.¹⁵ She added:

There has been no constructive self-reflection by government health officials and their vaccine industry partners examining the possibility that the public, especially parents of young children, have rational reasons for being concerned. Instead, yet another knee- jerk ‘it’s the fault of the anti-vaxxers’ campaign has been trotted out.¹⁶

Vaccinated People Spreading Measles Experience Milder Symptoms, Raising Concerns About Underreporting

Reporting by the Center for Infectious Disease Research and Policy (CIDRAP) on the newly published study that the vaccinated can spread measles and contribute to measles outbreaks noted that, “The most common symptoms among the 19 transmitters with symptom information were rash (16 people), fever (11) and cough (11). Most vaccinated people who spread measles experienced milder symptoms and a shorter illness than those who weren’t vaccinated. Most often, cough, breathing, or talking likely caused measles to spread.”¹⁷

The measles transmission study found that only seven of the 19 vaccinated transmitters (36.8 percent) for whom symptom information was available met the World Health Organization (WHO) clinical case definition for measles, while only one (5.3 percent) exhibited all five classic measles symptoms: cough, coryza (common cold), conjunctivitis, fever, and rash. The authors pointed out that vaccinated cases, particularly those experiencing secondary vaccine failure, often experience milder measles symptoms, and concluded that transmission from vaccinated cases “must be considered in public health investigations” because such transmission can contribute to outbreaks.¹⁸

Fisher publicly raised the issue of potentially undetected measles infections among vaccinated people in 2019:

How many unvaccinated children are being diagnosed with measles because they are fully expressing symptoms and are more easily identified and reported, while vaccinated children and adults are being asymptomatically infected or are only experiencing mild symptoms that are never identified or reported?

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