(CNN) US Customs and Border Protection will not vaccinate migrants, even though three children who had been in US custody died after contracting the flu.
The cases all occurred since December.
"In general, due to the short-term nature of CBP holding and the complexities of operating vaccination programs, neither CBP nor its medical contractors administer vaccinations to those in our custody," according to a statement Tuesday from CBP.
Migrants are supposed to held in CBP custody for 72 hours or less, but often remain there for longer.
After leaving CBP custody, children without parents are sent into the care of the US Department of Health and Human Services, where flu vaccines are distributed, according to Evelyn Stauffer, a spokeswoman for the Office of Refugee Resettlement, a part of HHS.
Public health experts had strong reactions to CBP's statement, saying the department should be able to vaccinate migrants, even if they're in CBP custody for only a few days.
"I think their answer is completely inappropriate," said Dr. William Schaffner, an infectious disease specialist at Vanderbilt University and an adviser the US Centers for Disease Control and Protection. "They ought to be able to do this. They create facilities that encourage the spread of infectious agents, with flu at the top of the list."
Flu activity in the United States typically begins to increase around October and many US pharmacies already have flu vaccines available.
Children younger than 5, and especially those younger than 2, are at high risk of serious flu-related complications, according to the CDC. Flu seasons vary in severity, but thousands of children are hospitalized each year related to the flu, and some children die. A flu vaccine offers the best defense against getting flu and spreading it to others, the CDC said.
On August 5, two members of Congress wrote a letter to the heads of the US Department of Homeland Security and HHS expressing concern about contagious diseases.
"When we visited the Homestead detention facility on July 15, 2019, we left with serious questions about the screening, treatment, isolation, and prevention protocols of infectious diseases, particularly influenza," Rep. Rosa DeLauro, a Democrat from Connecticut, and Rep. Lucille Roybal-Allard, a Democrat from California, wrote to Kevin McAleenan, acting secretary of the Department of Homeland Security and Alex Azar, secretary of the Department of Health and Human Services.
DeLauro and Roybal-Allard also sent McAleenan and Azar a letter from physicians at Harvard and Johns Hopkins urging vaccinations.
"During the influenza season, vaccination should be offered to all detainees promptly upon arrival in order to maximize protection for the youngest and most vulnerable detainees," the physicians wrote.