With measles on the rise, school gets riskier
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| Map showing where the most measles cases have been reported in the United States in 2026. Credit: CDC |
School starts
soon in north-central Colorado and pediatrician Shen Nagel, MD, is bracing for
the possibility of a measles outbreak.
In some ways this
is par for the course. After major holidays and summer breaks, kids bring
viruses back to their classrooms, and Nagel sees spikes of flu, respiratory
syncytial virus and other respiratory illnesses, among his patients at
Pediatrics West, a practice in suburban Denver.
Measles might soon be added to that list, though it wasn't a disease that pediatricians worried about much when Nagel started practicing 25 years ago. But post-COVID-19, dropping vaccination rates and conflicting federal messaging have created an opening for measles, widely considered the most contagious infectious disease known to humans.
The good news is
that most parents do get their kids the measles, mumps, and rubella (MMR)
vaccine, which is 97% effective after two doses. Experts who spoke to CIDRAP
News for this story say that if a fully vaccinated child has a normal immune
system, parents shouldn't worry about their child catching measles at
school—especially if that school has a relatively high vaccination rate.
Outbreaks are extremely unlikely in communities where overall MMR coverage is
95%.
All we need is one case to start something.
But uptake is
uneven. For example, the country's largest active measles outbreak is in
Lancaster County, Pennsylvania, where more than a dozen schools have MMR rates below 70%. In these
buildings, a single exposure can set off a cascade of hospitalizations,
mandatory quarantines, children missing school, and parents missing work.
"All we need
is one case to start something," said Nagel.
Schools are
higher-risk settings
Schools are
higher-risk settings for measles, said Zach Moore, MD, MPH, North Carolina's
state epidemiologist and president-elect of the Council of State and
Territorial Epidemiologists.
Kids tend to have more physical contact with each other than adults do, and classrooms are confined spaces. Also, particles of the measles virus can remain in the air up to two hours after an infected person leaves an area, so as students move from room to room throughout the day, they can become infected, even if everyone in their own class is healthy.
It seems that
unvaccinated kids are especially at risk if they attend a school with a lower
percentage of MMR coverage, said Moore, citing unpublished research North
Carolina did in collaboration with South Carolina and the US Centers for
Disease Control and Prevention. He anticipates the study will be released later
this year.
Generally, people
fully vaccinated with the MMR vaccine are a dead end for transmission. But
so-called breakthrough cases can occur; 3%
of the 2,566 measles cases reported in the United States so far this year were among fully
immunized patients. In the rare instance of a breakthrough, it's more likely to
happen in an environment where multiple people are infected
"The
intensity of exposure matters," said Moore, who added that a lot of fully
vaccinated kids who get measles catch the virus from someone they live with.
However, the MMR
shot prevents severe illness and long-term
complications, and
vaccinated people are less likely to spread the virus to others.
Outbreaks
becoming more frequent, intense
There have always
been clusters of unvaccinated kids and adults. But experts interviewed for this
story said that, before the COVID-19 pandemic, these pockets tended to be fewer
and smaller.
As recently as a
decade ago, MMR rates were high enough that parents who chose not to vaccinate
their kids could feel somewhat confident measles wouldn't enter their entire
community. In the rare event of an outbreak, public health workers could
intervene to prevent the virus from spreading to additional people.
Now that vaccine skepticism has become more prevalent, gaps in MMR coverage have grown. That's increased the frequency and severity of measles outbreaks, including school-based outbreaks, said Margot Savoy, MD, MPH, the chief medical officer of the American Academy of Family Physicians.
In Utah, for
example, a high school wrestling tournament in February led to measles
spreading throughout the state. With 526 cases and counting, Utah ranks second
to South Carolina in total infections for 2026, a record-breaking year for the
disease. The number of cases reported across the United States hit a 35-year
high in July, with year-to-date infections surpassing those reported for all of
2025.
"I'm getting
nervous because it's not getting better," said Savoy.
School nurses
on alert
School nurses
have been preparing for the possibility of measles outbreaks coming to their
districts for the past few years, said Lynn Nelson, MSN, president of the
National Association of School Nurses.
It's been roughly
two generations since measles posed this level of threat in the United States,
so recent preparation has included ensuring nurses can appropriately refer
families to medical care. People should phone ahead and not just show up at a
doctor's office, urgent care center, or emergency room so that clinicians can
take precautions to protect the health of other patients.
A pernicious
aspect of measles is that its first symptoms resemble other respiratory
illnesses and people are infectious up to four
days before the
telltale rash of flat red spots appears. That puts the onus on school nurses to
know which students are unvaccinated or immunocompromised, and to work with
other public health officials to identify exposures in the event of an
outbreak.
I'm getting
nervous because it's not getting better.
"Our kids
don't just live at school," said Nelson. "They go home to their
families and their grandparents and their pregnant moms and newborn
babies."
For this reason,
the American Academy of Pediatrics recommends that its members collaborate with school
nurses and advocate for adequate school nurse staffing, noting that just 65.7%
of schools have full-time nurses.
Younger kids
face the most risk
A small
percentage of people who get the measles will die or suffer life-altering
complications, including blindness, hearing loss, permanent scarring to the
lungs, intellectual disabilities, and other lasting neurologic deficits.
Additionally, the virus can erase pre-existing antibody cells, which leaves
people vulnerable to other viruses and bacteria for years.
MRI scans of the brain with SSPE. Credit: Bonthius1b.gif / Wikipedia
Perhaps the most
insidious outcome is a condition called subacute
sclerosing panencephalitis (SSPE), in which a latent measles infection mutates inside the brain,
causing progressive cell death and atrophy until the area of the brainstem that
controls breathing is destroyed. This rare disease shows up roughly a decade
later in people who seem to have fully recovered from a measles illness,
meaning it will be years before any SSPE cases stemming from recent outbreaks
emerge.
The younger the patient, the greater the risk of SSPE, fatality, or other devastating outcomes. That is why Nagel in Denver advises parents to get their baby an early MMR shot if they travel to areas in the United States where there is an ongoing outbreak. Normally, the first MMR is given at 12 to 15 months, and up until last year, Nagel recommended an early shot only when families traveled internationally.
Experts told
CIDRAP News that what's so maddening about the spread of measles is that, if
enough people were vaccinated, the disease could be eradicated. In fact,
vaccination rates were so high in the late 1990s that measles was declared
eliminated in the United States in 2000.
"We had
already figured this one out," said Savoy. "We were winning."
“It's never too
late to choose different," she added.
