CNN  — 

Abbott Laboratories says the supply of its at-home Covid-19 tests may be constrained in the coming weeks as demand has grown to “unprecedented” levels during the current surge of coronavirus infections driven by the highly transmissible Delta variant.

“We’re seeing unprecedented demand as case rates rise – and we’ve been scaling up manufacturing since Delta became the dominant strain and new CDC guidance called for a re-prioritization of testing,” Abbott spokesperson John Koval wrote in the email to CNN on Thursday.

“Today, there are tens of millions of BinaxNOW tests in various settings and supply chains. We’re working with our customers to ensure tests get to where they’re most needed and we’re ramping back up, as we did last year,” the statement said. “There will be some supply constraints over the coming weeks as increased capacity comes online.

“Today, BinaxNOW can be found in schools, universities, workplaces, retail shelves across the country, and other settings like nursing homes and assisted living,” said Abbott’s statement.

On Friday, an online search for Abbott’s BinaxNOW rapid antigen self-test yielded results to order tests via CVS and Amazon, but the test appears to be out of stock for online orders via Walgreens and Kroger.

Other test developers also have seen increased demand.

“We continue to see increases in demand for COVID-19 PCR testing due to Delta and as the school year begins,” Christopher Allman-Bradshaw, a spokesperson for the company Labcorp, told CNN in an email on Friday morning. “We report numbers on a quarterly basis that we have seen an increase in testing as caseloads rise.”

The company Quest Diagnostics also has noted a rise in demand for diagnostic testing.

“While COVID-19 molecular diagnostic testing demand and positivity rates have climbed in recent weeks due to the nationwide increase in COVID-19 cases, we are performing and reporting the majority of COVID-19 tests within 1 day,” Kim Gorode, a spokesperson for Quest Diagnostics, told CNN in an email on Wednesday. “We have ample capacity, but are adding molecular test instruments to bolster readiness in select laboratories in the Southeast and Southwest, where demand is comparatively high.”

Outside of at-home tests, the company Color – which offers Covid-19 testing kits for testing programs in schools, workplaces, special events or other settings – told CNN on Thursday that it has seen an increase in demand across all the different types of programs the company supports.

“It’s truly been across the board, and I think in particular right now, we’re seeing really the jumps as well from schools starting back up,” said Caroline Savello, chief commercial offer at Color.

Yet in general, Covid-19 testing capacity can vary depending on the type of test used.