Some 2,212,335 kits produced by the Australian-based biotech company Ellume and distributed in the US potentially show false positive SARS-CoV-2 test results, the public health agency said in a statement on Thursday.

The FDA warned that the use of faulty kits "may cause serious adverse health consequences or death," identifying the case as a 'Class I recall.'

The antigen test, which detects coronavirus proteins, was authorized for emergency use by the FDA last year. It is available without a prescription for both adults and children aged two and older, and uses swab samples taken from a nose to detect if one has Covid. Some "specific lots," manufactured between February and August this year, are now being recalled in the US, with the company saying it has worked with the authorities to voluntarily remove the affected tests from the market. The company has offered its apologies "for any stress or difficulties [customers] may have experienced because of a false positive result."