A measles outbreak in Texas has sickened 15 members of a church led by the daughter of televangelist Kenneth Copeland, who opposes government-required vaccines such as measles, mumps, and rubella (MMR) vaccine.

Most of the 24 cases are members of Eagle Mountain International Church, according to Tarrant County officials. The outbreak was prompted by a church visit by someone who had recently travelled to a country where measles is common. Measles was eradicated in the U.S. by the turn of the century, according to the Centers for Disease Control and Prevention (CDC), but sporadic outbreaks occur resulting from international travel. Fatal in one of 1,000 cases, measles still kills hundreds of thousands around the world every year.

The church announced on its website that the preacher and staff, the congregation, and all of the children at the onsite day-care center had been exposed by the visitor, sickening six adults and nine children ranging in age from 4 months to 44 years. At least a dozen of the affected congregants had not been fully immunized with a vaccine first approved by regulators in 1971. The remaining patients infected by measles lacked documentation proving vaccination, too.

All of the school-aged children sickened in the outbreak were home-schooled, whereas state law requires such vaccinations prior to attending public school. Highly contagious, the disease is transmitted through the air and can survive on surfaces for as long as two hours, according to the CDC. Without vaccination or disease immunity from experience, a person is 90 percent likely to contract the disease after contact with an infected person. Once, before the advent of modern childhood immunizations, measles infected 4 million Americans and killed 500 yearly.

The outbreak, along with recent flare-ups in Minnesota and San Diego, typically occur after unvaccinated travelers infect other unvaccinated people in the U.S., William Schaffner, a medical professor at Vanderbilt University, told USA Today. "This is a classic example of how measles is being reintroduced," Schaffner said.

In a statement Aug. 15, pastor Terri Pearsons expressed reservations about vaccines. "The concerns we have had are primarily with very young children who have family history of autism and with bundling too many immunizations at one time," she said. The preponderance of scientific evidence supports the safety of MMR vaccine and fail to find a link between the three-shot regimen and alleged development of autism spectrum disorder.

Schaffner criticized the preacher for the statement. “At this point, this is not only sad but silly,” he told USA Today. “This is a sadly misinformed religious leader.” According to Schaffner, Pearson’s advice to congregants to take vitamin D as immune system-boosting disease protector is also unwise. No medical evidence exists to suggest that vitamins boost the immune system, whereas most evidence shows that vaccines safely prevent infectious diseases such as measles.