Coronavirus Shedding; Airborne Transmission: It’s TTHealthWatch!

Coronavirus Shedding; Airborne Transmission: It’s TTHealthWatch!

TTHealthWatch is a weekly podcast from Texas Tech. In it, Elizabeth Tracey, director of electronic media for Johns Hopkins Medicine, and Rick Lange, MD, president of the Texas Tech University Health Sciences Center in El Paso, look at the top medical stories of the week. A transcript of the podcast is below the summary.

This week’s topics include a look at transmission of SARS-CoV-2 in South Korea, a review of studies relative to transmission of SARS-CoV-2, inappropriate use of cardiac stents, and risk of breast cancer death after DCIS.
Program notes:
0:52 Cardiac stents in people with stable heart disease
1:56 Stenting rarely beneficial
2:53 Number of stents decreased by 84%
3:51 Save $6 billion avoiding stents
4:05 Risk of death from breast cancer after ductal carcinoma in situ
5:05 Looked at SEER database
6:05 DCIS thought to be contained
7:00 Review of COVID transmission
8:02 Most people don’t transmit
8:47 Transmission in asymptomatic and mildly symptomatic
9:47 20% never showed symptoms
10:44 13 days later still tested positive
11:44 Resistance domestically
12:55 End
Transcript:
Elizabeth Tracey: What do asymptomatic and mildly symptomatic patients with SARS-CoV-2 infection teach us about viral shedding?
Rick Lange: Viral host and environmental factors that affect COVID transmission.
Elizabeth: What’s your risk of dying of breast cancer if you’ve had DCIS or ductal carcinoma in situ?
Rick: And addressing inappropriate use of stents in treating people with heart disease.
Elizabeth: That’s what we’re talking about this week on TT HealthWatch, your weekly look at the medical headlines from Texas Tech University Health Sciences Center in El Paso. I’m Elizabeth Tracey, a Baltimore-based medical journalist.
Rick: I’m Rick Lange, President of the Texas Tech University Health Sciences Center in El Paso, where I’m also dean of the Paul L. Foster School of Medicine.
Elizabeth: Rick, how about if we start with one of yours today? You tell me, surprise me, which would you like to choose?
Rick: Let’s talk about stenting in people with stable heart disease.
Elizabeth: Okay, that’s in JAMA Internal Medicine.
Rick: There are actually two articles we’ll talk about and an editorial that also follows these articles. There are literally hundreds of thousands of stents placed in coronary arteries around the world and we know they’re effective in people that have a heart attack or impending heart attack.
People that have stable heart disease, where they have stable symptoms, what we’ve discovered from recent studies is stenting can actually relieve the symptoms. But in terms of preventing death or heart attacks, they’re really not any more effective than good medical therapy. Now we’re recommending that there be less stenting done for stable heart disease unless people have symptoms that aren’t treatable by typical medications.
These two studies tried to address the inappropriate uses of stents in two ways. The first was they looked at what are called appropriate use criteria in the American Heart Association, American College of Cardiology and said, “Would a stent be appropriate, maybe appropriate, or inappropriate in these particular individuals?”
Before these studies came out that indicated that stenting in stable heart disease really wasn’t beneficial for preventing death or a heart attack, rarely was the stenting thought to be inappropriate, only about 2% or 3% of the time. But now, based on the current data, that number is as high as 22% or 23%.
The other thing is there have been recent reports of use of the U.S. False Claims Act. This was an act that whistleblowers used to try to identify people who had been defrauding the government. They’ve actually applied that to physicians that were inappropriately putting stents in. What happened is the physician would look at the blockage in the artery and they would overestimate it, and based upon that would then put a stent in and the patient probably never needed it. There are at least 16 cases where this has been applied. What they did was they looked at the hospital use of stents before the U.S. False Claims Act investigations began and then afterwards.
What they discovered is over the course of years in those hospitals, eight hospitals in these 16 cases — by the way, there were three physicians sent to jail over this — the number of stents placed in patients with stable heart disease decreased by 84%. In the control group, it decreased by about 64% as the data came out suggesting it wasn’t useful. What this suggests is, number one, using appropriate use criteria, and secondly, enforcing criteria can help decrease the use of stents that are inappropriately placed.
Elizabeth: As you’re well aware, as a procedure-averse person, I’m fully in support of that data in these specific patients. I’m just wondering about what happened to that cohort over the long haul. I’m not sure that that’s in that study.
Rick: No, neither study suggests that. But in the studies that these use criteria were based upon, individuals that had stents really didn’t do any worse than people who were just on good medical therapy. They just didn’t do any better and so why would you put someone through the risk of a procedure and the cost?
By the way, they estimated that if we actually applied these criteria as it’s supposed to be applied, we’d save about $6 billion annually in the United States just restricting stent use to people that actually receive a benefit from it.
Elizabeth: Right, and I guess that for me is the most compelling factor, which is, gosh, we could save the healthcare system a tremendous amount of money by being more appropriate.
Rick: Absolutely. What do you want to talk about next?
Elizabeth: Let us go to JAMA Network Open. Since you started us out with the non-COVID material, I’m going to follow your lead here. I found this study to be really interesting. It was taking a look at women who had had a diagnosis of DCIS, ductal carcinoma in situ, and looking at their long-term risk of actually dying of breast cancer.
What they did is identified women with primary DCIS diagnosed between 1995 and 2014 from the SEER (Surveillance, Epidemiology and End Results) database. They had a total of a 144,000-plus women who were diagnosed in this way and their mean age at diagnosis was 57.4 years. I thought it was rather young.
During this period of follow-up, there were 1,540 deaths from breast cancer and the mortality ratio for death from breast cancer among women with DCIS was 3.36, so they were 3 times as likely to die after their diagnosis of DCIS, of breast cancer, as women who were not in that category.
I thought that was a really interesting statistic because previously many people have been opining that DCIS is generally pretty benign — if you catch it and you treat it, then you really don’t have much of a risk of dying of breast cancer — and that in this case is just not true.
They also broke out different groups and found out that if you were Black you had a really dramatically increased, 8 times higher, risk of dying of breast cancer subsequent to that diagnosis than you were otherwise.
They looked at whether the recurrences were ipsilateral or contralateral. For the most part, they were evenly distributed there, so that doesn’t really give us any information about that. Ultimately, they conclude that, “Hey, we probably need to be doing something else after DCIS.”
Rick: For our listeners that may not be aware of it, DCIS refers to cancer cells that are in the breast tissue but they don’t extend beyond the basement membranes of the cells. It’s thought to be contained. These are typically found in women that undergo routine mammography. They’re not usually symptomatic. There’s thought that, as you mentioned, it wasn’t life-threatening.
We do a lumpectomy or mastectomy, take it out, sometimes may or may not use radiation therapy, that we could actually prevent them from dying of cancer. As you suggest, these women are still 3 times more likely to die of cancer as women that never have DCIS.
Now, the absolute percentages are still fairly low. A 20-year risk of someone with DCIS dying of breast cancer is only 3%. But as you highlight, Elizabeth, it’s higher in Blacks and young women with DCIS, where the risk could be as high as 10%. What this paper doesn’t do is it doesn’t give us any insight into the best therapy.
Elizabeth: Yeah. We definitely need to have some kind of surveillance that’s a little more effective, clearly, on what’s going on right now. Let’s turn to your next one, turning back to COVID material in Annals of Internal Medicine.
Rick: This is a review. The data show pretty convincingly that most of the transmission occurs via respiratory droplets. It can be aerosolized, but that’s really a very small fraction of the transmission. When it occurs, it’s usually in areas with poor ventilation.
Real world studies suggest that catching it by fomites — that is on surfaces — is extremely rare. In fact, they’re not even sure there have been any reported cases of fomite transmission nor of fecal-oral transmission.
Individuals, as we’ve talked about, can become infectious days before they present with symptoms and it seems like the highest viral load occurs about out 1 day before the people actually present with symptoms when they do, although there is virus detected 2.5 to 3 days before.
There is probably a minimum amount of virus that needs to be transmitted to the individual and, furthermore, as we’ve talked before, individuals are infective for usually 6 to 8 days after they’ve developed symptoms and 10 days in someone that’s had a severe infection.
You can detect virus from 20, 30 or 40 days afterwards with routine testing, but those individuals are not infectious at that particular time. Either the virus is not transmissible or the viral load is particularly low.
Then finally, most people who get it really don’t transmit it. There are probably a small group of super spreaders. About 80% of the infections are caused by about 10% of the people with COVID infection and your risk of developing from a household contact is somewhere probably between 10% and maybe as high as 19%.
There are very few incidences of what’s called vertical transmission. That is mothers that are COVID-infected giving it to their newborns. Elizabeth, any other things that you want to know with regard to transmission?
Elizabeth: No, not really. I think that that was a pretty comprehensive view of what it is we know so far and, of course, definitely undergirds all the things that we’re trying to do to avoid transmission.
Rick: Absolutely, and it would suggest that what we’re doing is really effective in preventing COVID infection.
Elizabeth: Finally, let’s turn to Thorax. This is a BMJ, or British Medical Journal, study taking a look at viral shedding among asymptomatic and mildly symptomatic patients with SARS-CoV-2 infection. This was in South Korea.
Lots of interesting aspects of this study, for me at least, included the fact that it was in South Korea and they were able to isolate this cohort in a way that in many other places — including here in the United States — we would never be able to herd all the people together and take a look at this.
They took all these folks who were thought or known to be infected with COVID-19 or be exposed to it and they put them all together into this what amounts to a living community where everybody’s got that commonality. “Okay. If you’ve been infected or exposed, we’re going to ship you off to this place and that’s where you’re going to stay.”
In 213 patients with infection, they remained asymptomatic, even after their potential exposure, to laboratory confirmation and admission. 20% of those folks never manifest symptoms.
They also showed that a large proportion of their mildly symptomatic patients showed persistent, positive upper respiratory PCR results at follow-up, what you’ve already identified, that this could stick around for quite a while.
Rick: They were able to do this because they identified a cluster related to a single religious group with over 3,000 people with a wide range of symptoms and they got put in the isolation facility so they could be continually tested. Which is great because we don’t have really any good studies on following asymptomatic individuals. We can identify some, but we don’t have a large group, and this provided it. As you mentioned, about 20% of the individuals that tested positive were asymptomatic and remained so.
Here is the other interesting thing. They tested them then and they tested them 13 days later, asymptomatic and symptomatic. What they discovered was 55% to 65% of individuals still tested positive essentially 2 weeks later, even though were not infectious.
More importantly, they measured the viral loads in the asymptomatic and symptomatic, because the thought was, “Well, if you’re asymptomatic, you really don’t spread it because you don’t have that much virus.” What they determined was the viral load was the same in both asymptomatic and symptomatic individuals, which means they’re still potential spreaders even though they’re not manifesting symptoms.
Elizabeth: Right. The other thing that I thought was interesting was they have this admission criteria they’ve identified for, “Hey, who’s going to get shipped off to our isolation facility?” They have a metric that’s called their COVID-19 National Early Warning Score.
They score these folks and say, “This is how risky or likely it is that you could end up being infected, and therefore potentially infectious.” I think that’s really fascinating and, again, I wonder about how much resistance we would encounter domestically if we tried to employ such a thing.
Rick: I think it would be a hard sell here, but it’s been very effective in countries like South Korea and Vietnam, for example, in preventing the spread. They have been extremely effective because they isolate those individuals. They test them consistently, so they’re not allowing even asymptomatic individuals to be circulating in the population, and now knowing that their viral load is the same that could potentially spread it. These are countries that are able to do things that we may not be able to do in a free, democratic society, but it has been very effective in controlling the spread of infection.
Elizabeth: Of course, I’m going to push you into a corner here and say, “Would that mean that you would advocate for this kind of thing if we could possibly employ it here?”
Rick: No, I think it’s very difficult to do. Not only do you isolate individuals, but it has a profound effect on the family, in terms of education and the economics as well. It’s very difficult to do in a democratic society and easier to do in a communist society.
Elizabeth: On that note, that’s a look at this week’s medical headlines from Texas Tech. I’m Elizabeth Tracey.

Rick: I’m Rick Lange. Y’all listen up and make healthy choices.
Last Updated September 25, 2020

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