Results discrepancy eludes easy answers
MANCHESTER — It was Friday, July 10, when a Manchester-area family realized their school-age child had a low-grade fever and gastrointestinal symptoms.
Knowing that fever and diarrhea are potential symptoms of COVID-19, the family sought testing at Manchester Medical Center the next day.
"We didn't necessarily think it was COVID. Under normal circumstances we wouldn't even consider taking to the doctor but out of an abundance of caution we decided to," the child's father said.
The child tested positive using an antigen test administered by the clinic — one of 65 who would test positive over the coming days.
"Our family took proactive action and began our own contact tracing," the child's father told the Journal. "Other families were informed of the situation and these families made their own determination of how to proceed. Most decided to get their own test at MMC."
The family spoke with the Journal on condition they not be named, in order to preserve medical privacy.
That same family has now found itself part of a puzzle that has baffled local doctors and the Vermont Department of Health: Despite the symptoms and the positive antigen test, the child later tested negative on a follow-up PCR test.
"To my knowledge everyone in our circle, including my child, tested negative with the follow up PCR," the father said.
The family also tested negative, and the child is feeling fine, the father said. If there was a COVID infection, it's not clear how the child got it, he said.
The child was one of five patients whose antigen test was positive that day, said Dr. Janel Kittredge-Sterling, the co-owner of Manchester Medical Center.
"All of them made sense. They all had symptoms. I did not look at those tests and go 'well, that doesn't make sense,'" she said Monday.
A MYSTERY UNFOLDS
Now, they're all part of an epidemiology puzzle that has the entire state wondering: Why did so many positive antigen tests for COVID-19 at Manchester Medical Center result in negative PCR follow-up tests from the state Department of Health?
Kittredge Sterling, the co-founder of MMC, joined Dr. Mark Levine, the state's health commissioner, on Vermont Public Radio's "Vermont Edition" on Monday afternoon to address that question.
While the two doctors didn't arrive at an explanation, both pledged cooperation in search of answers — and reminded residents of Manchester and its surrounding mountain towns that regardless, continued vigilance is crucial in preventing spread of the highly communicable virus.
The manufacturer of the test and testing equipment, San Diego-based Quidel, said on Wednesday that it had reached out to the clinic and is investigating the findings.
Quidel Marketing Director Jeannine Sharp Mason said the company will have a representative on site in Manchester this week "to gather intelligence, talk with those involved, download and analyze the instrument data, and observe the physical operation."
"The clinic believes that their positive test results are accurate. At this time, there is nothing to indicate a failure of the Quidel test system," Mason said.
While the state now says there is not an outbreak of the virus in Manchester and the nearby mountain towns, the data remains confounding. Levine said Tuesday that his department is working with the U.S. Centers for Disease Control and Prevention to solve the puzzle.
There have been 65 positive antigen tests reported by MMC as of Wednesday. But of the follow-up PCR tests reported, only four have returned positive.
Overall, Levine said, there have been 1,613 PCR tests taken in the Manchester area in the past week, in pop-up testing conducted in Londonderry and Manchester and in follow-ups to the antigen tests. Of those, five have returned positive, he said.
"We were using the diagnostic and decision making tools we have in forming differential diagnosis," Kittredge-Sterling said of the tests her clinic conducted after July 10. "We were not just randomly swabbing everybody."
"When those happened and clinically made sense I said to myself we have a slight issue ... my concern was knowing the demographics of those folks and activities in town, and it started to make me nervous."
The Manchester-area family said they support MMC's decision to make those test results public — results that would not have been made public by the Department of Health, because it uses the PRC tests as confirmation.
"With that said I firmly believe MMC did the right thing. They believed there was a potential problem and they believed in their test," the father said. "Clearly there is a discrepancy but I think more questions need to be asked regarding the state guidance and state test and not just blame MMC. At worst, they erred on the side of caution, and at best, MMC was on to something and slowed the spread.
"I believe that they were on to something."
NEW TEST, NOT NEW EQUIPMENT
Manchester Medical Center has been using testing equipment made by San Diego-based Quidel since the clinic opened in 2019, Kittredge-Sterling said. Like many other private practices, MMC had difficulty obtaining PCR test kits, and it began using Quidel's COVID-19 test when it was made available by the U.S. Food and Drug Administration in May.
"We spent a great deal of time researching and receiving data to ensure this was accurate," Kittredge-Sterling said of the equipment. It was routinely calibrated and the staff was trained in its proper use, she said.
What's the difference in tests?
The antigen test looks for the presence of certain proteins that are part of the virus, while the PCR test — which stands for "polymerase chain reaction" — seeks the virus' unique genetic signature. The antigen test's benefits are that it returns results much more quickly than the PCR test, which can take days.
Both tests are considered highly effective in detecting positive results. Their downside, more so for the antigen test, has been the number of false negative results — telling people they're not COVID-positive when they actually are.
But no medical test is 100 percent effective. Kittredge-Sterling said she's personally aware of coronavirus cases in which the patient returned multiple negative PCR tests for COVID-19, but clearly had most of its symptoms — extreme fatigue, fever, respiratory symptoms, and conjunctavitis.
So what's really happening?
"This is what makes this extremely unprecedented like every other aspect of this epidemic," Levine said. "I don't think this has been encountered anywhere before."
On VPR's "Vermont Edition" with host Jane Lindholm, Levine laid out a number of potential theories, but quickly added reasons why many of them seem unlikely:
- Are the antigen tests correct and the PCR tests incorrect? "It would be unlikely to have such a large number of PCRs if that were true," Levine said.
- Are the antigen tests correct and the PCR tests were taken too late? "That doesn't seem really likely either, because there was a huge number of PCR tests and because the vast majority of followup was within two days of the antigen test," Levine said.
- Could the antigen test have picked up another coronavirus, resulting in false positives from another virus? "That's not supposed to be likely but the FDA is allowing emergency use (of the antigen tests) without a lot of preliminary data," he said.
- Are equipment malfunctions or human error at fault? "The physicians at MMC have assured me they pay very special attention to that," Levine said.
Kittredge-Sterling raised the possibility that the time it takes to get PCR test vials from Southern Vermont to their laboratory destination might play a role. It takes hours, sometimes days, for those vials to reach their destination, she said.
"Is there something with the testing media that's making [COVID-19] undetectable? Is it the delay? Is it the temperature at which vials are being stored in between transport time? I look at all of the possible reasons we have this discrepancy, because the only way to manage the pandemic looking forward is to find where the break in the chain is occurring," she said.
Also appearing on the program was Dr. Trey Dobson, the chief medical officer of Southwestern Vermont Medical Center in Bennington. He said the testing dilemma highlights the importance of people following the behaviors that are already proven to reduce spread of the virus.
"Let's all act as if we have this whether or not we have a (positive) test," he said.
On Tuesday Levine reported that officials in Maine are dealing with a similar issue. The Bangor Daily News reported that the Maine Center for Disease Control would be revising its count of "probable" cases from a summer camp, which it did not identify, that used antigen testing. The story is similar to Southern Vermont's story: The camp's antigen tests were positive, and the state's follow-up PCR tests were negative, the Daily News reported.
GROWING CONCERN AND A CHOICE
Earlier Monday, Kittredge-Sterling said that between May 20 and July 1, the clinic conducted about 700 tests to rule COVID-19 in or out for people who had similar symptoms. The results were all negative for the coronavirus.
"People were coming in with a sore throat, fatigue, nausea, they were here from Brooklyn, they'd been in a wedding party," she said.
That changed July 1 with a single test — a positive from a teenager visiting the area with family.
Fourth of July weekend was quiet, she said. But July 10 brought five positive cases — not all from the same family or social group.
"There were different pockets of positives — it wasn't random. They had symptoms that made sense significant for COVID. A plus B was equaling C," she said.
In many patients, the symptoms being presented included gastrointestinal distress, such as nausea, cramps and diarrhea — all of which are on the list of symptoms for the virus.
As positive test results piled up over the weekend, Kittredge-Sterling had a decision to make about whether to to tell the community that it might have an outbreak on its hands.
"When I can't get a hold of the fire department, do I let the house burn? The wrong thing for me is to think 'these are false positives' and let these people roam," she said.
While experts try to understand the results — the clinic has been in contact with Quidel, and the U.S. Centers for Disease Control and Prevention has met with the state Department of Health — she wants to assure patients that the clinic acted appropriately, followed protocols, and made the results public in the interest of protecting public health.
"There's no conspiracy, there's no divisiveness, I'm not telling anybody not to trust the Vermont Department of Health," she said. "We have to work in collaboration ... to figure out why there's a discrepancy. Something happened, somewhere.
"We need to look at all the angles and I am transparent. If there is something that happened on our end, I will own it," Kittredge-Sterling said. "And I want people to know the truth about their health. I have nothing to gain in giving anybody false information. I want to know where does the discrepancy lie and if it's our testing, we will own that."
Reach Greg Sukiennik at email@example.com
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