Officials from the U.S. Immigration and Customs have confirmed that there have been 250 immigrant children who were administered adult doses, or double the doses for children, of the hepatitis A vaccine, Fox News reported.

The children have been detained at the South Texas Family Residential Center in Dilley, Texas, 70 miles southwest of San Antonio, and are now being closely monitored for any adverse reactions. The vaccines were given last week and monitoring will still continue this week. The ICE is confident there will be no side effects.

"Parents at the facility were advised and counseled by medical professionals about potential side effects, with services made available in multiple languages," said Richard Rocha, the spokesperson for ICE, the report said.

"If anything, you may get a higher immune response," said Dr. Peter J. Hotez of the National School of Tropical Medicine at the Baylor College of Medicine in Houston in the same Fox report.

Hepatitis A is a serious liver disease that can be transmitted through water and food contamination, according to the U.S. Center for Disease Control and Prevention. Symptoms may include stomach pain, diarrhea and flu-like manifestations

The agencies, together with the Homeland Security's Health Affairs, office are looking into what happened to the mix-up.

The facility reportedly received over 2,000 women and children immigrants from Central America last week. They entered the United States through Mexico. Meanwhile, another detention center in Karnes have about 400 immigrants.

Statements from volunteers at these detention facilities said that the centers "have long noted disturbing patterns of what appears to be inadequate health care." according to Fox. Immigrants' rights activists have been urging Homeland Security to lock down these shelters due to substandard conditions, according to LA Times.

The ICE, however, denies this was the case.