The Biden administration said Wednesday it is relaunching a program that allows Americans to order free COVID-19 tests through the mail, ahead of a potential surge of infections this winter.

The website, Covidtests.gov, will relaunch for new orders Monday. Households will be able to order up to four tests, which are intended for use through the end of the year. 

They will include clear instructions on how to verify extended expiration dates, the Department of Health and Human Services (HHS) said. 

The White House is also investing $600 million to purchase 200 million new tests from a dozen domestic test manufacturers.

HHS Assistant Secretary for Preparedness and Response Dawn O’Connell said the investment “will increase availability of tests in the future” and help the country prepare for future coronavirus surges and other pandemic threats of the future.

The U.S. government has shipped more than 755 million free COVID-19 tests to people who requested them through Covidtests.gov, HHS said, though it’s much harder to find free tests now.  

The program was suspended at the end of May to preserve the existing supply, but Health Secretary Xavier Becerra said Wednesday the stockpile has been replenished.

Private insurers had previously been required to cover up to eight at-home tests per month, but that ended when the Biden administration allowed the public health emergency to expire in May.

Additionally, the program that allowed Medicare coverage and payment for over-the-counter COVID-19 tests also ended when the emergency expired. 

COVID-19 cases and hospitalizations have been on the rise in the U.S. since July, though the numbers are still far below where they were during peak times of the pandemic.