A measles outbreak spanning multiple states is nearing 600 cases, and experts say it might just be the beginning.
As of Tuesday, Texas has reported 505 cases associated with the outbreak, New Mexico has reported 56 cases, and Oklahoma has reported 10: eight confirmed and two probable.
Cases in Kansas, which the state health department says may also be linked to the outbreak, reached 24 last week.
The outbreak began in rural Gaines County, Texas, where most of the cases are concentrated, but Tuesday’s update shows spread into 21 Texas counties. Local officials are particularly worried about spread of the measles virus into new areas and vulnerable populations, such as urban centers.
“I’m worried about exposures in grocery stores, malls and those types of places that don’t exist as much out in the rural community,” Katherine Wells, director of Lubbock Public Health, said Tuesday. “You have a much bigger population, so one case can be exposing a lot more individuals.”
In these areas, public health workers will need to do more to figure out who is at risk, who is exposed and who needs to isolate, she said. Some local health departments have said that recent cuts to funding from the US Centers for Disease Control and Prevention will hinder their epidemiology work and lab capacity for identifying measles cases.
In Lubbock, measles exposure in a day care center has resulted in seven cases in children under the age of 5, Wells said Tuesday. This is a particularly vulnerable community, as many of the children are not old enough to get their second dose of the measles-mumps-rubella (MMR) vaccine.
Under normal circumstances, the CDC recommends one dose of MMR between 12 to 15 months of age and another between 4 and 6 years. In outbreak situations, these guidelines may be updated.
“Our biggest challenge right now is really around younger children,” Wells said. “One of my biggest concerns was outbreaks in places where we have vulnerable individuals, individuals that can’t be vaccinated yet, or children that are undervaccinated because they’re only eligible for that one vaccine.”
The local health department is encouraging vaccination for other children at the day care center, in line with recommendations from the Texas Department of Health Services that children ages 1 to 4 in the outbreak area get their second dose as soon as possible, as long as it’s at least 28 days after their first dose.
Infants who are 6 to 11 months in the outbreak area can get an early dose of the MMR vaccine and will then resume the normal MMR schedule with two more doses.
Given the contagious nature of the virus and low vaccination rates in many pockets of the country, experts expect the outbreak to grow, possibly for more than a year. Continued spread of the virus for more than 12 months could threaten the measles elimination status the US earned in 2000, according to the CDC.
“I think it is going to be something that really pushes us to the deadline for elimination for the United States, as well as for the Americas,” Dr. Amesh Adalja, senior scholar at the Johns Hopkins Center for Health Security, said Tuesday.
Compared with other recent US outbreaks, cases are vastly undercounted in this outbreak, he said, in part because it has been concentrated in a Mennonite population that is undervaccinated.
“There might be reticence to get tested in some of those areas, [which] probably means that this is a lot bigger than the outbreaks that we’ve seen in the past,” Adalja said.
Three deaths have been connected with the outbreak: two school-age children in Texas and an adult in New Mexico whose death remains under investigation. All of these people were unvaccinated.
US Department of Health and Human Services Secretary Robert F. Kennedy Jr. touted the response to the outbreak on Tuesday.
“Our strategy has been very successful. … The growth rate has diminished substantially,” he said. “And so what we’re doing right here in the United States is a model for the rest of the world.”
But experts say it’s not so simple.
“I don’t think that RFK Jr. has the information to be able to say that. I don’t think any of us have full situational awareness of what’s going on with this outbreak. … We think cases are undercounted,” Adalja said. “You can’t say something is flattening if you don’t actually know the denominator of cases or [have] an understanding you’re getting [the] full capture of the cases.”
The outbreak will continue until the virus infects all susceptible people in the area, he said.
“All of these cases could be avoided if everyone who had the ability to be vaccinated did so,” said Dr. Christina Johns, a pediatric emergency physician at PM Pediatric Care in Annapolis, Maryland. “Our overall vaccination rates are declining, which is an anti-science trend, so I’m not sure the United States is a model at all in this regard.”
The CDC updated its measles guidance for health care providers across the country Tuesday, urging them to stay alert for possible cases. The agency noted that 12% of reported cases this year had been hospitalized and that the “measles-mumps-rubella (MMR) vaccination is the best way to protect against measles and its complications.”