President Joe Biden on Monday officially ended the Covid national health emergency that for more than three years underpinned extraordinary efforts to provide care for a country where more than a million people died from the disease.

The White House said Biden signed a law passed earlier by Congress “which terminates the national emergency related to the Covid-19 pandemic.”

This closes lavish funding streams for Covid tests, free vaccines and other emergency measures thrown together – starting in January 2020 – to try and free the world’s biggest economy from the grip of the global pandemic.

Less clear is the impact the end of the emergency will have on the already tense southern border with Mexico, where US authorities have long struggled to manage the flow of undocumented immigrants and large numbers of asylum seekers.

A rule known as Title 42 was used during the official health emergency to impose stringent restrictions on acceptance of undocumented arrivals. That is set to end, forcing the administration to adopt a different legal mechanism if it wants to avoid the politically damaging potential of new influxes.

A senior official in the White House told the media that the use of Title 42 “is expected to expire on May 11th.”

Although the US is now formally turning its back on the worldwide pandemic, the Biden administration is already working on a next generation vaccine and other measures to combat any future variant of the virus, the White House said.

“Project NextGen will accelerate and streamline the rapid development of next generation of vaccines and treatments through public-private collaborations,” according to senior administration officials.

A fund of at least $5 billion is available to “help catalyze scientific advancement” and “stay ahead of the rapidly evolving virus that causes Covid-19.”