This spring, a child in southern Missouri tested positive for the measles virus after returning from an international trip. The Taney County patient was the state’s first reported case of measles so far this year. Soon after, health workers confirmed another case in an adult in southern Illinois. Officials confirmed a case in a visitor to the St. Louis Aquarium soon after.
Usually, these reports don’t raise many eyebrows — the state often reports a handful of measles cases in Missouri annually.
But this year, health workers are on high alert. Cases of measles, which public health officials had once declared eliminated in the United States, have exploded in Texas and other parts of the country. According to the Centers for Disease Control and Prevention, 12 outbreaks in 29 states, including Missouri and Illinois, have sickened more than 900 people this year.
In Missouri, public health officials have watched warily as the case count has ticked up across the country while the measles vaccination rate among Missouri kindergarten students has decreased: It’s now 91% in public schools and 85% in private schools. Because measles is so contagious, that means Missouri communities could be at risk of the virus spreading and sickening some of the youngest patients.
“We are, epidemiologically, absolutely at risk for measles,” said Dr. Heidi Miller, the chief medical officer at the Missouri Department of Health and Senior Services. “We know when the measles immunization rates dip below 95%, we are absolutely at increased risk. Currently, those numbers are at least 5 points too low. That can make a huge difference.”
A slam-dunk vaccine
As school nurses in the Webster Groves School District, Meagan Lozano and Rachel Winingham prepare for whatever a sick kid might need. Lozano not only keeps Band-Aids and ice packs in her office at Clark Elementary, but also Cheerios, stuffed animals and detangling cream for hair knots.
Winingham, the district’s lead nurse, said she’s keeping an eye on the students in the district who aren’t vaccinated.
“We would be worried for anybody in this school or out in the community that was exposed,” she said. “Just because the potential complications are scary, right?”
According to the CDC, 96% of confirmed measles cases this year are in those who are unvaccinated or whose vaccination status is unknown. More than 1 in 10 of those sickened this year have needed to be hospitalized, according to the agency.
“Some of these kids that are being hospitalized are getting really sick with some of the severe complications, like pneumonia,” said Lozano, who is president of the St. Louis Suburban School Nurses Association. “It can lead to brain infection. Those children were previously healthy, and they were just not vaccinated.”
Usually, children receive the first dose of the vaccine that protects for measles, mumps and rubella (MMR) after their first birthday and the second dose around age 5. But fewer people are choosing to vaccinate their children, opting out of some or all of the recommended immunizations.
Lozano and Winingham aren’t especially worried about Webster in particular – the district has a vaccination rate around 97%, and unlike other vaccinations, such as the flu shot, the MMR vaccine is kind of a slam dunk.
“The really great thing is that the vaccine is highly, highly effective at preventing [someone] for the rest of your life from getting [measles],” Lozano said. “And then if you can't get measles, then you can't transmit it, so you can't share it with others.”
Scientists estimate that the “herd immunity” level needed to stop the spread of measles is around 95%. If the rate drops below that threshold, it’s easier for measles to rip through a community.
“The lower the vaccination rate is in any subset of people in any population, the quicker it's going to spread,” Winingham said. “So the [fewer] people who are vaccinated, the faster it spreads.”
Not all counties in the state have such a high vaccination rate, though. In St. Louis County, 92% of kindergarteners have received the MMR vaccine, and that share drops more in St. Louis.
“If you don't have that full high threshold of people that are vaccinated or immune to it … then that's why it can spread like wildfire,” Lozano said. “And not just in the school setting. Measles can be spread through the air up to two hours after a person with measles has been there.”
Lessons learned
Miller thinks there are several reasons for decreasing vaccination rates among Missourians.
The internet and social media make it easy for people to spread misinformation about vaccines, and people are more likely to come into contact with that content, she said.
But vaccine misinformation isn’t the only factor causing the rates to fall. Children may not have a regular pediatrician to visit. Families may have lost track of vaccine schedules during the economic chaos of the coronavirus pandemic.
“There is definitely a statistical correlation that parents of low income and whose children are uninsured or have less access to health care have lower vaccination rates,” Miller said. “There is also a concern that if kids don't have a regular place of care and only resort to going to urgent care, they don't have the opportunity for preventive services to keep them healthy.”
A 2024 study of parents seeking nonmedical exemptions to vaccine requirements in St. Louis County showed many of the respondents thought it was better for children to develop “natural” immunity to diseases. Many respondents said that children get more vaccines than are good for them and that they don’t want children getting many vaccines at once.
The study found that the majority of parents seeking nonmedical exemptions did not agree that many of the vaccine-preventable diseases are severe.
That’s something Miller has encountered in her own interactions with patients. The measles vaccine has potentially become a victim of its own effectiveness, she said. Many in the United States haven’t seen someone who has been severely sick with measles, so it’s easy for people to think it’s not a huge risk.
Miller said physicians learned a lot about how to talk – and how not to talk – to people about vaccinations during the coronavirus pandemic. Cajoling and scolding aren't very effective, she said.
“Sometimes patients will assume that I'm going to immediately fight them about their vaccine decision, and I don't,” she said. “One of the first things I say is that the decision to vaccinate them or their child is a deeply personal decision, and whatever they choose is fine. And that tends to calm the room, dissolve any sense of confrontation.”
Health workers should be honest about potential risks of vaccinations, Miller said. With any health intervention, there are risks and benefits. In the case of the measles vaccination, she said the benefits far outweigh risks or side effects.
“It's our state public health department's responsibility to empower citizens with information, information that is reliable, and to be very transparent about what we know and what we don't know,” Miller said.
Watching and waiting
As more measles cases are being reported around the country, officials at the St. Louis and St. Louis County health departments are preparing for the eventuality that more cases emerge.
The region’s health systems and governments have reactivated the pandemic task force, a mainstay of the coronavirus years, to prepare for the virus arriving in the area, said Dr. Mati Hlatshwayo Davis, outgoing St. Louis health director.
The group discussed clinical and reporting requirements for when a case is found, she said.
“The hospitals are well equipped. Our federally qualified health centers are well equipped. What is important to me as the director of health is that we're all in communication and working well,” she said.
What does concern her is the vaccination rate among the city’s children — among the lowest in the state, she said.
“I do not want us to be in a situation where we drop below herd immunity and start to see some of the levels of really fast transmission that you saw in Texas that did have lower rates of vaccination,” she said.
Hlatshwayo Davis is particularly concerned about misinformation coming from higher levels of the government, she said. Newly appointed Health and Human Services Secretary Robert F. Kennedy Jr. became known in the past for perpetuating now-discredited ideas about a link between autism and vaccines.
“I believe that we're seeing a trend that is going backwards,” she said. “What I would like to see is us get back to transparent, vulnerable and responsible conversations that are rooted in science that we have vetted for such a long time.”
