The following information is from Children’s Health Defense.
A senior Centers for Disease Control and Prevention (CDC) official acknowledged that measles vaccination does not guarantee immunity, citing recent outbreak data that included infections among fully vaccinated people.
In a Feb. 1 letter to The Wall Street Journal, CDC Principal Deputy Director Dr. Ralph Abraham said that during a 2025 measles outbreak in Colorado, four of nine secondary infections occurred among people who had received two doses of the measles, mumps and rubella (MMR) vaccine.
The outbreak involved 10 people and began with an unvaccinated international traveler. All patients recovered, according to the CDC’s Morbidity and Mortality Weekly Report.
The CDC later confirmed the breakthrough cases in a public statement.
“Although vaccinated individuals are at low risk of acquiring measles, breakthrough infections can still happen.”
— CDC, statement on X
Abraham wrote that vaccination alone cannot fully control outbreaks, even in highly vaccinated populations.
Brian Hooker, Ph.D., chief scientific officer for Children’s Health Defense, said the CDC’s messaging downplays important limitations of the vaccine.
“US residents need complete public health messages, not just vaccine commercials by the CDC.”
— Brian Hooker, Ph.D., Children’s Health Defense
CDC data estimate one dose of MMR provides 93% protection against measles, while two doses raise protection to 97%. Hooker said those figures do not account for waning immunity.
“This number has never been corrected historically and doesn’t reflect waning immunity over time.”
— Brian Hooker, Ph.D.
Karl Jablonowski, Ph.D., senior research scientist for Children’s Health Defense, said the outbreak highlights questions about vaccine effectiveness.
“Either the measles vaccine is not as effective as it purports to be, or there was an extraordinary coincidence of vaccine failure.”
— Karl Jablonowski, Ph.D.
Pediatrician Dr. Michelle Perro said breakthrough measles cases are often underrecognized.
“Breakthrough cases are real, diagnosable and often underdetected.”
— Michelle Perro, M.D.
Abraham said similar outbreaks have occurred in other countries with high vaccination rates, arguing that US policy should not be singled out.
For more information, read the full article here.
