PORTLAND, Ore. (KOIN) — Seemingly rare as rubies, at-home rapid COVID-19 tests have flown off store shelves across the country — and now some versions of the test kits have become more expensive.

Amid the omicron surge, Kroger and Walmart have increased prices on Abbott Laboratories’ popular BinaxNOW test kits, after a selling agreement with the White House expired in December 2021.

The initial agreement between the Biden administration and Abbott Laboratories granted Kroger, Walmart and Amazon the ability to sell BinaxNOW test kits to customers at a 35% discount over a three-month period.

“As the President announced in early September, Kroger is one of three national partners who agreed to make at-home, rapid COVID-19 tests available to customers at cost for 100 days,” Kroger spokesperson Tiffany Sanders said. “Of note, we fulfilled our commitment to the Biden administration to sell at cost for 100 days and that pricing program has now phased out and (pre-commitment) retail pricing has been reinstated.”

Now that the agreement is over, participating retailers are forced to sell the kits at standard pricing, which has raised the average cost per test kit by approximately $8. In an effort to cater to customer demand, Walmart agreed to extend the company’s discounted test kit price of $14 past the 100-day agreement, before raising the cost to $19.88.

“The program ended in mid-December,” Walmart spokesperson Tricia Moriarty said. “While other retailers increased prices in mid-December, Walmart held the $14 through the holidays before increasing the price.”

The same 2-count BinaxNOW test kit is currently listed for $23.99 on Fred Meyers and Kroger websites.

Even with the price increase, the demand for testing has not slowed down. At the time of this article, online options for BinaxNOW kits at Kroger and Walmart websites show the kits to be out of stock or otherwise unavailable.

Kroger and Walmart representatives independently told NewsNation affiliate KOIN the companies are experiencing major supply shortages for COVID-19 test kits.

“We have seen significant demand for at-home COVID-19 testing kits and are working closely with our suppliers to meet this demand and get the needed product to our customers,” Moriarty explained.

Walmart said the company has held strong inventory levels nationally in stores, but test kits have been more limited online. Due to this trend, Walmart said they have introduced a purchase limit on BinaxNOW test kits of “8 testing kits per online order to help ensure availability to more customers.”

Kroger said the company is currently working to develop solutions to the mass test shortage, which would impact local supplies.

In a statement, Kroger Director of Corporate Communications Kristal Howard said, “We are also actively adding other manufacturers to increase product availability across the country, including the Pacific Northwest.”