About 250 immigrant children were given an adult dose of a hepatitis A vaccine at a Texas detention facility where they were being held with their mothers, according to US Immigration and Customs Enforcement officials.
The vaccines were administered this week, but none of the children has been hospitalised or had any adverse reactions, ICE officials said on Saturday
ICE spokesperson Richard Rocha said health care professionals will monitor the children over the next five days for any potential side effects, though none are expected.
"Parents at the facility were advised and counseled by medical professionals about potential side effects, with services made available in multiple languages," Rocha said in a statement.
According to the Centers for Disease Control and Prevention, the hepatitis A virus can cause liver infection and is usually transmitted among individuals and through the consumption of contaminated food or water.
Dr. Peter J. Hotez, dean of the National School of Tropical Medicine at the Baylor College of Medicine in Houston, said the children likely received double the pediatric dosage of the vaccine. He said they should continue to be monitored, although it's unlikely that they will see short- or long-term complications.
"I'm guessing there will not be significant effects," he said. "If anything, you may get a higher immune response."
ICE and the Department of Homeland Security's Office of Health Affairs are investigating how the mix-up at the South Texas Family Residential Center in Dilley occurred and how such mistakes can be avoided in the future, Rocha said.
As of earlier this week, the center about 70 miles (113 kilometers) southwest of San Antonio held about 2 000 women and children, most from Central America and who entered the US via Mexico seeking asylum.
Crystal Williams, executive director of the American Immigration Lawyers Association, which has provided pro-bono legal services to the women and children in the detention facilities, said in a statement that volunteers "have long noted disturbing patterns of what appears to be inadequate health care."
"This latest permutation is beyond appalling," Williams said in the statement.
But ICE has previously said that the health care professionals at the centers provide quality medical care and that the agency takes "very seriously the health, safety and welfare of those in our care."