The U.S. Food and Drug Administration (FDA) is classifying the recall of the Ellume COVID-19 Home Test for giving false-positive results as a Class I recall, according to MobiHealthNews.

The agency said this is the most serious type of recall, adding the “use of these tests may cause serious adverse health consequences or death.”

COVID can be a serious illness and a false-positive result could further delay diagnosis and treatment, further spreading the virus when presumed positive people are staying in a group.

In addition, the FDA warned false-positive results could lead people to avoid vaccination if they think they already had the virus or push them into isolation without cause.

Last month, Ellume started recalling certain lots of the test. On Wednesday, the FDA added the classification and said the company had identified more defective lots since the agency’s original alert. The total number of affected tests went around two million.

So far, there have been 35 reports of false-positive results, with no deaths reported. The FDA said negative test results haven’t been affected, according to MobiHealthNews.

In early October, the FDA issued a warning about the company’s app-connected home tests giving false-positive results.

The FDA issued Emergency Use Authorization (EUA) to Ellume COVID-19 Home Test in December. The Biden administration made a $232 million deal with Ellume to increase the availability of its tests in the U.S. in February.

Ellume spokesperson told MobiHealthNews in an email, “While we cannot speak on behalf of the FDA, this is a follow-up to the agency’s announcement last month of Ellume’s voluntary recall in order to provide an update on the recall’s classification and additional lots impacted.”

“Ellume has investigated the issue, identified the root cause, implemented additional controls, and we are already producing and shipping new product to the U.S.,” they added.

The spokesperson said, “Importantly, not all of the positive results of the affected tests were false positives, and negative results were not affected by this issue.”

“The Ellume team offers its sincere apologies for the stress or difficulties people may have experienced due to a false-positive result. We have and will continue to work diligently to ensure test accuracy, in all cases.”