Dozens of people have tested positive for COVID-19 in the Manchester area, and hundreds more flocked to pop-up test centers in southwest Vermont to help assess the scope the outbreak. But only a small number of those positive results were confirmed by more-accurate PCR testing. This hour, we talk with state and local health officials to get the latest on this surge in possible coronavirus cases.
Our guests are:
- Dr. Mark Levine, commissioner for the Vermont Department of Health
- Dr. Janel Kittredge, emergency medicine physician and co-owner and medical director of Manchester Medical Center, which ran antigen tests on 64 patients in Bennington County
- Dr. Trey Dobson, chief medical officer for the Southwestern Vermont Medical Center in Bennington
Broadcast live on Monday, July 20, 2020 at noon; rebroadcast at 7 p.m.
The following has been edited and condensed for clarity.
Update 1:42 p.m. July 21, 2020: 65 people have tested positive for COVID-19 at Manchester Medical Center with an antigen test. 52 of those people have now had PCR tests, four of which were positive.
Jane Lindholm: There were as many as 59 people who had tested positive in recent days for COVID-19. But the tests that had been used were antigen tests. Health Commissioner Dr. Mark Levine said PCR tests had come back on 17 of the people who had previously tested positive with antigen tests, and only two had tested positive on these PCR tests.
This is really confusing to many people. Why weren't you doing PCR tests on people in July instead of antigen tests? My understanding was you actually didn't have all the materials for a follow up PCR test on hand in the last couple of weeks. Is that true?
Dr. Kittredge: That is true. It's been challenging to obtain the PCR swabs in all honesty. Initially, in the earlier days of March, we could only get them from the Vermont Department of Health. We have been able to receive some now from UVM Medical Center. But in the early days, when there were limits on how many swabs we had available, we would somewhat be rationed. So, we had to be really particular as to how we used them and who we used them on. And that, again, is part of that decision making.
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Jane Lindholm: Dr. Levine, when you've been asked in press conferences in the past, the state has said that we have enough swabs right now to meet our needs and certainly enough to be testing a thousand people per day with PCR tests. So, what's happening with the swabs that Dr. Kittredge doesn't have?
Dr. Levine: Dr. Kittredge represents just one of the abundant primary care practices throughout the state. So the state has not become the primary resource for all of the primary care practices. We have a number of audiences for all of the supplies we do have. We routinely partner with the University of Vermont Medical Center. We routinely refer primary care practices who are looking for such things as swabs to their customer service team, where they find there are options for where they can get supplies that they're in need of. We did, though, just to be on record, send 300 kits last Tuesday to Manchester Medical Center, knowing that there was this urgent need in the community.
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Jane Lindholm: So, despite the fact that the state says we have enough supplies, there may be times when not all practitioners have all the supplies they need on hand for PCR testing?
Dr. Levine: That could be possible. Absolutely.
Jane Lindholm: It sounds like what the official statement is right now is that antigen tests are highly accurate for positive cases but have a higher rate of false negatives. Do you see that still being the best medical guidance on antigen tests, Commissioner?
Dr. Levine: Yes. The bottom line is they are regarded as very, very highly specific. And that means that basically, if there is a positive result, there's a very low likelihood that it's a false positive. But they're not regarded as sensitive, so if there is a negative result, there is a likelihood that that could be a false negative, in which case one would follow it up in the right clinical setting with another test like a PCR.
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Jane Lindholm: So, of the 59 people who tested positive on antigen, 17 were tested with PCR, and only two came back positive. Why do you think that is?
Dr. Levine: So the 59 positive antigen tests is now up to 64. And out of the 64, 35 have additionally received PCR tests that we're aware of. And out of the 35, there are still only two positives. A total of 288 PCR tests were done in Londonderry and over 1,100 PCR tests were done in Manchester. Out of 1,423 PCR tests, there were three positives. So that indicates that there's very little in the way of community transmission occurring from at least that parameter, using that type of test, and indeed looking at the percent positivity rate.
And in Vermont and in these two counties, Bennington and Windham counties, that percent positivity rate remains well under 2%. And the overall infection rate in Vermont didn't change last week either.
"Out of 1,423 PCR tests, there were three positives. So that indicates that there's very little in the way of community transmission." -Dr. Mark Levine, Commissioner for the Vermont Department of Health
Jane Lindholm: So, what is your best understanding of why that would be, given what we know about antigen tests being highly sensitive for positive cases?
Dr. Levine: This is what makes this discrepancy extremely unprecedented, like every other aspect of this epidemic. I don't think this has been encountered anywhere before to my knowledge. There's a lot of possibilities, and I can run through a list:
- These antigens could actually be true positives and we shouldn't believe the PCR.
- We are possibly not looking at these cases the right way, and they are actually very strongly positive even before you did a test.
- The antigen test was positive, and the PCR test was obtained too many days after that positive test, so it had already turned negative.
- The antigen test is a false positive because of another coronavirus circulating in the community that caused it to cross react, [or there was] a laboratory error, an analytical error or contamination.
The antigen test is recommended by the CDC and the Association of Public Health Laboratories to be used for people WITH symptoms. We don’t have evidence about the accuracy of the antigen test on people without symptoms. (4/5)
— VT Dept of Health (@healthvermont) July 17, 2020
Jane Lindholm: Dr. Kittredge, what do you think is happening here?
Dr. Kittredge: Vermont has been in a very stable place for a long time. And as health care providers, I was really proud of that and thankful for the strain that doesn't put on us. But I will say, we have become a little too comfortable perhaps, in letting our guard down. The swimming holes have been jam packed and the restaurants are busy and [people are] shopping and socializing. So Fourth of July weekend happens, and then six days later is when we had those first five cases.
Some possible reasons for the discrepancy between the PCR and antigen testing are:
- There has been an interesting GI [gastrointestinal] prevalence with nausea, abdominal cramping and diarrhea with this spike and I question if that is part of where we're not perhaps picking it up on PCR.
- I have questions about the viral transport media. When we have to take a swab, we put it inside a vial that contains a viral transport media to stabilize the virus. It then has to undergo hours and sometimes days to make it from one facility to the lab to be processed. So I question, is there something with the viral transport media that's making this virus undetectable, whether it’s the delay, the temperature or something else?
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Jane Lindholm: I think this highlights how many questions there still are. If people test negative, from your perspective, should they trust their test results?
Dr. Dobson: Well, I would say if they were symptomatic and they tested negative, the answer would be most likely, yes. It doesn't mean, though, that therefore they go out and congregate with lots of people inside without wearing masks. That type of behavior we know not to do. But if someone is symptomatic and tests negative, they should be shedding virus that both the antigen and PCR tests should easily be able to pick up.
Jane Lindholm: That in some ways is almost more confusing because it's saying if you test negative, but you're symptomatic, you should trust your negative result. However, if you test negative and you're not symptomatic, then you really don't know whether you have it or not.
Dr. Dobson: Well, I think it goes to show you that we have to look at each case and we have to have a provider who can help that patient make those decisions. So certainly, there could be cases where people are ill and test negative, but if they're ill, they're not going to be going out and interacting with people anyway.
But I do think that we are going to move forward on learning more and more on these tests, working all together, not only locally, but as a nation and as a world in figuring out how can we do testing in a way that is inexpensive, done in the home or the business, without needing a doctor's order, that is accurate enough that we can do it on a daily basis. There's a lot of people writing about the potential to test before going to school. And I do think that will be possible if we can devote the resources to getting that done. The technology actually already exists. It's just [a matter of] mass producing it and getting it out to the public.
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Jane Lindholm: What should we be thinking about this particular situation?
Dr. Kittredge: It is certainly very confusing, and I empathize with that for sure. I want nothing but the best for everyone in our community, state and across the country. And so when we have this little uptick in cases — and I'm not calling it an outbreak because it's not an outbreak — but when we have a presentation, we have an intruder that got loose, I just want folks to tighten it up a little bit. We got a little complacent. And we want to be, because we want life to go back to normal. But that's just not where we are right now in the country... We need to all act as if we really have this, whether or not we have a test. [And if you are symptomatic] and get a negative test, you need to act like you really have this, despite what that test said.
"We got a little complacent and we want to be because we want life to go back. But that's just not where we are right now in the country." -Dr. Janel Kittredge, Medical Director at Manchester Medical Center
Jane Lindholm: For people who worry about what's happening in this particular situation, how do you advise them?
Dr. Levine: The whole issue here is what I call universal precautions. If we're sick, we stay away and we stay home. If we're out, we keep up a physical distance of six feet. We wear masks and we make sure that we keep our hygiene up with washing our hands a lot, because when you have perhaps 20% - some estimates are as high as 50% - rate of transmission from asymptomatic people to others, we all need to make that assumption that anyone we're around, including ourselves, could potentially be a person who could spread the virus.
Dr. Kittredge: For local businesses that are asking how they can move forward, my answer is we can still live our lives. We can still go to school, go to restaurants and shop. But we need to modify a bit and unfortunately, we have to think a bit harder about how to live day to day, in a way that we haven't had to do before. The more diligent we are now, the safer we will be and the sooner we can be rid of the masks and physical distance guidelines.
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