After denying problems with their $13 million coronavirus antibody testing program, Chester County officials on Tuesday acknowledged that the tests, purchased from a local biotech start-up, produced “potentially inaccurate” results that the county concealed from the public — and even from the thousands who took the tests.

The county vowed this week to reach out to those who received the “questionable test results” in late May and to appoint a consultant to review the purchase of the antibody tests.

“In hindsight, communication of the potential inaccuracies of the antibody tests should have been provided to test recipients” who were tested on days when the results were in question, the county said in a statement.

The about-face follows an Inquirer report last week showing that Chester County spent $13 million in federal pandemic aid on a no-bid contract to Malvern-based Advaite at the suggestion of State Sen. Andy Dinniman (D., Chester County). Because of the public health emergency, governments can enter contracts without seeking competitive bids.

The testing program was intended to identify essential workers who had developed disease-fighting antibodies, which show up in the blood after COVID-19 infection. Ultimately, the plan was to pay $20 million to test all one million residents of Chester and Delaware Counties to better understand the scope of local infection, and how long antibodies might provide immunity to the deadly virus.

In the first few weeks after testing began May 7, Advaite’s product produced results that seemed accurate.

But suddenly on May 21, the percentage of people testing positive for coronavirus antibodies began spiking to levels far above what was plausible, based on the prevalence of the virus in the area, according to internal emails and interviews.

On June 2, the county quietly shelved the program.

The U.S. Food and Drug Administration says antibody tests should not be used to diagnose COVID-19. But Chester County health officials and their lab partner informed people who tested positive for certain antibodies that they could have a current infection, emailing them results that stated: “You may have COVID-19. You are likely contagious. You should isolate yourself at home.”

Some who received that alarming notification rushed to their doctor for a real diagnostic test — one that uses molecular analysis to detect the virus in nasal swabs — only to get a negative result. That could be because the antibody test was incorrect and they never had the virus, or because they had already recovered and the virus was no longer detectable by a diagnostic test.

Regardless, the county never informed those who may have received false alarms, nor did it disclose the questionable results — about 6,100 of the 19,425 tests it conducted — on its website.

Renée Cassidy ultimately resigned in July as the county’s public health physician to protest the handling of the problem. She said her superiors resisted stopping the program and notifying people when accuracy became a concern.

“They seemed very invested, like, ‘We have to keep going.’ And I’m like, ‘No, we don’t have to keep going if we don’t know what we’re doing is accurate.' ... They were overly married to this tool, in my opinion," Cassidy said.

As recently as last week, the county continued to insist that the tests had worked as advertised.

“Nothing went wrong with the antibody testing program,” Chester County spokesperson Rebecca Brain said in a statement last Wednesday.

The tests were purchased from Advaite in April. The company’s CEO, Karthik Musunuri, 26, is the son of Shankar Musunuri, a biotechnology veteran known to Sen. Dinniman. Shankar Musunuri had contributed $4,000 to Dinniman’s campaign committee between 2012 and 2020, and the senator had hired Musunuri’s younger son as a summer intern.

“Shankar is a most respected leader in the biotech field,” Dinniman told The Inquirer earlier this month. “Anything Advaite was doing, he was involved.”

Shankar Musunuri’s company, Ocugen, notified the Securities and Exchange Commission in April that it had a “collaboration” with Advaite. Ocugen would be paid up to $375 an hour to work on projects for his son’s firm, and it would also receive royalty payments based on sales of the test kit.

The Musunuris have not responded to requests for comment.

Chester County said on Tuesday that its three-member Board of Commissioners would appoint an “independent legal consultant to review the process associated with sourcing and procuring the antibody tests so recommendations may be provided on how policies and procedures can be improved."

Emails show that the Advaite invoice stated the tests were “non-returnable and payments non-refundable.”

In the Tuesday statement, the commissioners said they were “working to determine how to proceed regarding previous payments to Advaite for the antibody test kits, and we will pursue all available options to ensure the [federal] funding used to purchase the test kits is protected.”