The Centers for Disease Control and Prevention will lift a sweeping public health order that has allowed the U.S. to expel more than 1.7 million migrants, mostly at the southern border, since the Covid-19 pandemic began.

In a statement Friday, the CDC said it will lift the order on May 23 to give the Department of Homeland Security time to scale up a program to provide vaccinations to migrants crossing into the U.S. CDC Director Dr. Rochelle Walensky determined the order was no longer necessary after reviewing current public health conditions, spokesperson Kristen Nordlund said.

The Trump administration first instituted the order in March 2020 under a public health law known as Title 42 to stop the spread of Covid-19 across the nation’s land borders with Mexico and Canada.

However, human rights groups have denounced Title 42 as a blanket deportation policy that deprives people the right to apply for asylum under U.S. and international law. The overwhelming majority of the deportations have occurred during the Biden administration.

The CDC under Biden extended the order in August as the delta variant swept the world, but made an exception for unaccompanied children. In January, the CDC decided to keep order in place as the omicron variant caused an unprecedented wave of infection.

Last year, dozens of leading health experts from across the U.S. condemned Title 42 as “discriminatory and unjustifiable” with “no scientific basis as a public health measure.” They called on CDC Director Dr. Rochelle Walensky and Health and Human Services Secretary Xavier Becerra to rescind the policy. They argued that the U.S. can preserve public health and meet its humanitarian obligations by implementing masking and testing, and offering vaccination at the border.

A top lawyer at the State Department, Harold Koh, wrote a scathing internal memo criticizing the Biden policy as “inhumane” and “illegal” when he left the administration in October.

Leading Democrats including Senate Majority Leader Chuck Schumer have repeatedly called on Biden to rescind Title 42. Republicans and conservative Democrats want the policy to remain in place as the Department of Homeland Security prepares for significant increase of border crossings.

Sen Joe Manchin, D-W.V., asked CDC Director Walensky in a letter this week to extend Title 42 as the more contagious omicron BA.2 variant spreads around the world. Sen. Kyrsten Sinema of Arizona, which shares a long border with Mexico, also supports keeping the order in place.

The CDC is easing public health measures as Covid infections and hospitalizations have plummeted more than 90% since the peak of the omicron surge in January. The public health agency ended its warning system for cruise ship this week.

Earlier this month, the CDC said 98% of people in the U.S. live in areas where they no longer need to wear a mask.