The provider of a COVID-19 rapid-results antigen testing platform that returned 65 positive results at a Manchester urgent care clinic in early July said Thursday it has found no problems with the test or procedure and believes the results were valid.
Douglas Bryant, president and CEO of Quidel Corporation, the San Diego-based manufacturer of the rapid-results antigen test, said the company found "no testing site or product-related issues" and believes the positive results were accurate while questioning the follow-up polymerase chain reaction test accuracy.
"Quidel takes every complaint seriously and endeavors to identify the root cause of any complaint received," Bryant said in a news release. "We conducted a very thorough investigation for this unique complaint in Vermont and believe that it was highly likely that our results were true positives and that the subsequent PCR method used to re-test was at risk of providing inaccurate results."
Manchester Medical Center, using the antigen testing platform, tested hundreds of people suspected of contracting the virus, including some who had symptoms consistent with COVID-19 when they were tested. The test returned 65 positive results sending a shock wave through the towns of Manchester, Londonderry and nearby communities.
Businesses closed, the Londonderry town offices shut down and strict precautions were instituted.
Of the 65 positive results only four individuals tested positive on follow-up testing using the PCR method. Another 1,613 people were tested using the PCR test at pop-up testing sites in Londonderry and Manchester set up by the Department of Health and a week long testing site in Manchester run by Southern Vermont Health Care. One one additional positive case was detected.
Vermont Public Health Commissioner Dr. Mark Levine reported on July 24 that the U.S. Food and Drug Administration had opened an investigation into the discrepancy and assigned a research scientist to the case.
Quidel reported that it too examined the "discordant results" in cooperation with the FDA and reported Thursday that its review included an inspection of the testing site, analysis of the site's data, and a review of approximately 110,000 data points generated at 526 sites in 33 other states currently using Quidel's product.
"The investigation found that there were no issues with either the testing facility or with the quality of the Sofia products used," according to the company's press release, referring to the brand name for its testing equipment. "The results of the investigation determined that no further actions were necessary, and results were provided to the Vermont Department of Health, the Centers for Disease Control and Prevention, and the U.S. Food and Drug Administration."
The PCR test is the most common testing platform in use, but the results can take several days to return. The antigen test, which was approved for emergency use in May by the FDA, can provide results in about 15 minutes.
Both tests claim a high level of accuracy in detecting COVID-19, but the antigen testing has a higher rate of false negatives, missing the virus at about double the rate of the PCR test, according to the FDA.
In Vermont, a positive antigen test is considered a presumptive positive by the Vermont Department of Health and requires a follow-up PCR test for confirmation and does not count people with a positive antigen test in the state's official statistics.
Abigail Martin, a spokesperson for Manchester Medical Center, when reached late Thursday said the clinic owners would have no comment until they had a chance to coordinate with state officials.
Contact Darren Marcy at email@example.com or by cell at 802-681-6534.