(CNN) -- The Biden administration has notified facilities caring for migrant children that they can open back up to pre-Covid-19 levels, acknowledging "extraordinary circumstances" due to a rising number of minors crossing the US-Mexico border, according to a memo obtained by CNN.
The increase in arrivals of unaccompanied children put additional strain on the immigration system, which was operating under limited capacity as a result of the coronavirus pandemic.
"We recognize the challenge of having these unaccompanied children come across the border and the influx that we're certainly preparing for and, and preparing to approach," said White House press secretary Jen Psaki Friday.
The Department of Health and Human Services is charged with the care of unaccompanied migrant children until they're placed with a sponsor, like a parent or relative, in the US, but with precautions to avoid spread of Covid-19 in place, the department is only able to use a little more than half of the beds it has for children.
There are approximately 7,700 unaccompanied children in HHS care. The department has around 13,650 beds to accommodate children when not under reduced capacity.
A separate document, prepared by the Centers for Disease Control and Prevention, calls the situation an "extraordinary" circumstance and says "facilities should plan for and expect to have COVID-19 cases," citing the nature of the pandemic and acknowledging "there is no 0% risk scenario."
CNN reported this week children were staying in Border Patrol custody for longer than three days on average, overwhelming capacity at border facilities. The average time in Border Patrol facilities, which are not designed to hold children, was 77 hours, longer than the 72 permitted under US law.
Friday's memo underscores the Biden administration's challenge to keep children out of Border Patrol custody.
"Additional shelter capacity will minimize the likelihood that children remain in Border Patrol stations longer than necessary, where they are also exposed to COVID-19 transmission risks as well as child welfare concerns associated with such settings. Overcapacity at Border Stations poses a greater infection risk to children than [Office of Refugee Resettlement] program sites that may operate at full licensed capacity with comprehensive COVID-19 mitigation measures in place," the memo reads.
"Today based on CDC guidance, ORR has notified facilities they may temporarily reactivate capacity to their full licensed capability up to safe occupancy levels," the memo continues, underscoring that reactivating beds should be done in a safe manner. The Office of Refugee Resettlement is the federal agency under HHS tasked with the care of migrant children.
The CDC document advises shelters to put Covid-19 mitigation measures in place, like using masks, distancing, cleaning and disinfection, improved ventilation, increased testing, and vaccination for children over 16 years old.
HHS also recently opened an overflow facility in Texas to house children arriving to the US southern border without a parent or relative, until they can be relocated with family in the US.
"We have to look for facilities and places where we can safely and humanely have these unaccompanied minors in the interim," Psaki told reporters Friday.
This story has been updated with additional details.