In our weekly check-in with the Vermont Health Department, we talk about reopening the economy while preventing further spread of COVID-19. We also ask what officials know about the scope and timeline of community transmission in the state.
Our guest is:
- Dr. Mark Levine, commissioner of the Vermont Department of Health
Broadcast live after Gov. Phil Scott's press conference on Monday, April 27, 2020; rebroadcast at 7 p.m.
The following has been edited and paraphrased for brevity and clarity.
As the governor begins to open the spigot, one quarter turn at a time on Vermont's economy, how will the state decide what the right threshold is for spread of the coronavirus within the general population once more people are back at work?
Commissioner of Health Mark Levine: That is a very challenging balance to strike.
Clearly, we can’t have an entire society living as isolated as some people feel in a physical distancing framework for the long term. On the other hand, we want to protect the most vulnerable among us.
There are some experts across the country who feel that there is a small rate of viral infection within the general population that would be considered “healthy,” if you will. So that there is an opportunity for some element of the population to gain some immunity, if we find that is indeed protective in the future.
The rate that we are dealing with now of positive tests is very low — in the single-digits. Right now, if we do 100 tests, we may find that up to five of those tests come back positive. So that’s where we’re starting from, as we enter this time where we are starting to reopen Vermont.
Before, we were seeing positive rates of 10% or or higher. However, those rates are still very small when compared with places where there are or have been active outbreaks — other states and locales have seen positive testing rates as high as 30% or 40%.
"There are some experts across the country who feel that there is a small rate of viral infection within the general population that would be considered 'healthy.'" — Health Commissioner Mark Levine
Below the 10% threshold would be compatible with where we are now as a baseline. We are going to have to look at any deviations from that very closely, moving forward.
Vermont was experiencing 10-12% positivity rates for testing when we were at our peak. If we got back to a point where we were seeing close to 10% of people being tested testing positive, I think that’s likely to feel like a crisis to Vermonters. What would you say to that?
We’d have to look at how many of those cases were symptomatic, not symptomatic, what populations were being affected. Were there implications for the healthcare system in terms of capacity issues? All of that would have to be looked at very carefully.
For a list of answers to some frequently asked questions about coronavirus, head here.
We will also look at incidences of new cases and at deaths, should they occur. we would again have a baseline now of very low numbers of new cases on a daily basis. That way, even if we do more testing, find more positives, the question would become: how many new cases are we finding in Vermont each day that are affecting the population at large?
Can you address the issue of non-symptomatic transmission? Are we anticipating there will be a time when we are testing asymptomatic people as well?
We already are and we will be.
For instance, when we go into a long-term care facility, we are often doing so because there was a positive test result there. We end up testing the entire staff and residents at that point, because we want to protect those very vulnerable patients.
In some cases, we end up identifying many people who test positive but actually have no symptoms.
We’ve also tried to do some preventative testing at a very large nursing home in the Southern part of the state and at a hotel that housed homeless individuals, some of whom were symptomatic. We were surprised to discover that all of the people in both those facilities tested negative.
So testing is an interesting proposition. When you try to understand what the disease carriage rate is within the population, you sometimes get surprising results one way or another.
What about asymptomatic people? Is it fair to say we don’t know the rate of asymptomatic spread?
Worldwide, this is a question we would love an answer to.
To explain the rapidity of spread across the world and the rate of spread in places where things have occurred in a much more explosive fashion [than Vermont], there had to be transmission occurring among people in an asymptomatic state, and probably in a pre-symptomatic state as well.
In the pre-symptomatic stage, people can transmit the coronavirus up to 48 hours before they may develop symptoms.
How reliable are COVID-19 tests and at what rate do false positives occur?
When you look at the PCR test, which is done on the nasal or oral secretions of a patient, those tests are looking at the amount of viral copies in a given specimen. To have a highly accurate test of this kind, you want to be able to detect a very small viral copy.
"In some cases, we find that we are identifying many people who test positive, but actually have no symptoms." — Health Commissioner Mark Levine
These test are, as scientists say, “exquisite” in the level of detail they can detect when it comes to viral copy. However, that only gives you a sense for how the test operates in the laboratory, not in a clinical setting. When you factor in variables like the conditions the test was obtained under, how it was stored, transported, the question of how accurate the test is becomes a concern.
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These tests were released very quickly with use authorizations from the FDA to get them into circulation, so there isn’t much on this in the literature. Best estimates from the medical community indicate that at a low estimate, they yield false negatives at a rate of 5%, and at a high estimate, at a rate of 20%.
Testing people twice could increase the yield. One could conceive of a false negative occurring if you tested someone when their viral load happened to be low.
How does that line up with what you had said about asymptomatic or pre-symptomatic transmission?
It’s really hard to understand that. People may have a significant viral load without classic symptoms.
There was also a phenomenon that was characteristic of the SARS virus, which was a coronavirus that was much more lethal but short-lived in the general population, that said there are people who are “super spreaders.” These are people who, in a less-than symptomatic state can infect multiple other individuals at close range, and cause a significant degree of illness.
Given this information, do we have enough tests to sustain the monitoring that will be required to sustain a reopening of the state right now?
For weeks on end now, we’ve actually been specifically asking all clinicians to test their patients for COVID-19, even if someone had only the mildest symptoms.
We really do have enough tests at this point in time. I’d be cautious to say that if Vermont was reopened excessively rapidly — and we know that won’t happen — that we couldn’t be overwhelmed by this, but the reopening is being done in a calculated and phased approach, that will allow us to keep careful awareness of our testing capacity and supplies.
What do we know about how long community transmission has been going on in Vermont? Is it possible that someone could have contracted COVID-19 in, say, November, or February and recovered and just thought it was something else?
November seems a bit early. There is widespread agreement that the epicenter was in Wuhan, China, and that it occurred in January.
Given what we know about the entry of the virus into the United States, if it did infect Vermont before the first case that we are aware of, I think it could have happened in mid-to-late-February at the earliest. But it would be challenging to figure that out now.
Where do we stand with antibody testing in Vermont? Will we see mass-testing soon?
A few states have jumped on the bandwagon and decided to test large numbers of people in the general population. However, most of the literature is saying that we don’t yet know how accurate the available tests are and it would be dangerous to give people false confidence. On the other hand, we don’t want to falsely alarm people that they have been exposed to the virus.
In healthcare, you have to think: What is the value? That’s about quality over cost.
We in Vermont are not interested in implementing a passport system of the sort that has been discussed. Further, these tests are not accurate enough yet to be used as a safety tool.
The conclusion of the taskforce of medical professionals I assembled to research the matter, has concluded that we need to wait a little longer. I am hoping that will mean a couple of weeks, but we will continue to reassess so we know when the right time is to apply this testing to the general population.
How would the Health Department use serology testing when it is available?
"If it did infect Vermont before the first case that we are aware of, I think it could have happened in mid-to-late-February at the earliest." — Health Commissioner Mark Levine
I could see it being helpful in informing policies that let people return to work. From a public health standpoint, it could help us understand how prevalent the virus has been in the population at large.
Early estimates suggested that, in this initial round of growth, 20-50% of Americans would come down with COVID-19. Now, the estimate is down to 10%. This means that if we have a second peak of the virus, there will be a large number of Americans who are susceptible.
Lastly, if there is an opportunity in a year to provide a vaccine for people, it would be important to know who should be prioritized to get it.
If you have good reason to believe you have contracted COVID-19 and recovered, but were never tested to confirm your case and are interested in donating your plasma for research into a possible treatment, when is the right time to do that?
Now is a good time. There are trials going on as we speak, and our university here in Vermont is participating. That’s a great place to donate, so that if your plasma is suitable, it can be used to determine in a proper clinical trial setting whether this could be used as a treatment for people with COVID-19.
