The source of the measles outbreak in Texas has not been determined, a top Texas official said on March 3.
Cases of measles first cropped up in Gaines County in January. Since then, an additional 144 cases have been confirmed.
Many measles outbreaks are caused by a person who travels outside the country and then returns with the disease.
A handful of cases identified in Harris County, also in January, were determined to be travel-related. Those patients did not spread the disease, which spreads through respiratory droplets, Shuford said.
As for the outbreak that started in Gaines County, “We don’t know who introduced measles into the community and from what country,” Shuford said later during Monday’s hearing. “We just don’t know that about this particular outbreak.”
She also acknowledged, under questioning from state Rep. Mike Olcott, that suggesting the source was travel-related was speculative.
Olcott noted that the number of illegal immigrants coming across the U.S.-Mexico border has surged in recent years and asked whether Shuford would agree an illegal immigrant could have been the source. She said she would not.
“We’ve seen examples where it’s not travel from our southern border, that it’s other travel that just happens to get into a pocket of under-vaccinated. And that’s why I can’t pin it on this,” she said. “I don’t have any data that would say yes or no.”
Of the 84 patients with known vaccination status, 79 were listed as not having received any doses of the measles, mumps, and rubella (MMR) vaccine. Another five had received at least one dose.
A school-aged child who died was unvaccinated, officials said.
Children are advised by the U.S. Centers for Disease Control and Prevention to receive one dose of the MMR vaccine at 12 to 15 months of age and a second dose at age 4, 5, or 6.
Gaines County and surrounding areas have recorded falling vaccination rates for years.
The percentage of conscientious exemptions to at least one vaccine was much higher in some counties, such as Gaines County, where the outbreak started. The percentage was 13.6 percent among school students there. And just 82 percent of kindergartners and 90 percent of seventh graders in the county had received a full series of the MMR vaccine.
At 95 percent coverage, herd immunity, or broad protection among the community is achieved, Shuford said. “We know when those vaccine levels get lower than 95 percent that there’s enough unprotected people together to cause an outbreak or to allow an outbreak to happen,” she said.
She attributed falling vaccination rates to a decrease in trust in vaccines.
State Rep. James B. Frank noted that the vaccination schedule from the Centers for Disease Control and Prevention contains dozens of doses, many more than other developed countries. He asked whether public health officials should focus on messaging that conveys to people that certain vaccines are high-reward and low-risk, such as the MMR vaccine.
Shuford said that the MMR vaccine “is one of our really good ones” while other shots, such as the COVID-19 vaccine, don’t work as well. “Part of it is on us in public health not communicating well,” she said.
For people who are exposed to measles and are unvaccinated, Texas officials recommend a vaccine within 72 hours of exposure. If that is not accomplished, unvaccinated children who were exposed are at risk of being excluded from school. Texas Administrative Code states that a child “who has not received the required immunizations for reasons of conscience, including religious beliefs, may be excluded from school in times of emergency or epidemic declared by the commissioner of the department.”
Shuford could not say how many children are being prevented from attending school.
