Flu season is coming. But for migrants in U.S. custody, vaccines won't be provided, despite the fact that influenza has contributed to the deaths of at least three detained migrant children since December.

"In general, due to the short term nature of Customs and Border Protection holding, the time the vaccine takes to begin working, and the complexities of operating vaccination programs, neither CBP nor its medical contractors administer vaccinations to those in our custody," the CBP said in a statement to USA TODAY.

People who require vaccines may receive them at a local medical facility, if necessary, the CBP said. In circumstances with public health considerations regarding vaccination, the agency coordinates with local health authorities and CDC for support, the CBP said.