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 data on two COVID-19 vaccines, the impact of physical distancing, universal masking, and contract tracing and transmission in South Korea.
Program notes:
0:47 Two vaccines going to phase III
1:43 At 28 days and 56 days
2:45 Mild to moderate side effects
3:50 Impact of physical distancing in reducing spread of COVID-19
4:50 Public transport in lockdown?
5:50 Mass gatherings
6:11 Universal masking impact
7:12 Tested those with symptoms
8:12 Provide masks for patients
8:25 Contact tracing in South Korea
9:30 Stratified according to decade of life
10:30 Very large study
12:12 End
Transcript:
Elizabeth Tracey: What does contact tracing in South Korea tell us about coronavirus transmission among kids?
Rick Lange: Using masks to protect healthcare workers.
Elizabeth: What is the impact of physical distancing on COVID-19 transmission?
Rick: And encouraging results from vaccine trials.
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 the Dean of the Paul L. Foster School of Medicine.
Elizabeth: Rick, because it’s so absolutely, critically important, I’m going to ask you to start first with these two studies relative to two different vaccines that look like they’re poised to now, I think, go into phase III trials for COVID-19.
Rick: You’re right, Elizabeth. Both of these trials, one in Wuhan, China and the other in five different centers in the United Kingdom. They’ve both used adenovirus vaccines — and these are non-replicating viruses — but these vectors contain the full-length structural surface spike protein. That’s a protein that the virus uses to attach to cells.
The vaccines were tested in a Phase 1 and Phase 2 trial, one in about over 1,000 individuals and the other in about 500 individuals. The study’s primary endpoint was looking to see, did they develop immunoglobulin — that is antibodies — to the virus, and specifically, did they develop neutralizing antibodies? Secondly, was there a cellular response, that is immune cells?
In both studies, approximately 85% to 95% of individuals did develop not only the antibody, but also the neutralizing antibody. The studies only looked at the effects at 28 days and 56 days. By the way, these studies both had a single dose and a smaller number of individuals had a booster dose at 28 days. But even in the single-dose administration, the effect looked like it lasted in one study for at least 28 days and in the other study for at least 56 days.
In addition, more than 90% of individuals also had a cellular response as well. The T cell numbers went up. The T cells elicited proteins like gamma interferon that we know help to rid the virus, so this is great.
Elizabeth: I think the T cell data is especially interesting because it’s clear that those T cells are really important in ongoing immunity.
Rick: Right. Even in some individuals that may not have a very robust antibody response, they still might be able to tamp down the virus, either to prevent it or to tamp down the symptoms, if they have a robust cellular response.
Now, the thing I didn’t mention and usually ask about, “What are their side effects?” About three-fourths of individuals did experience some systemic effects: fever, fatigue, headaches, pain at the injection site. Most of them were mild to moderate in nature, and by the way, they were ameliorated by giving a non-steroidal anti-inflammatory medication. Two to 10% of individuals did have a more severe reaction, so it did appear to be overall well-tolerated. As you’ve mentioned, Elizabeth, these are now both going to phase III trials in tens of thousands of individuals.
Elizabeth: I think that I’m really comfortable with this adenovirus vector — we have abundant experience with that — and I’m a little suspicious about the mRNA, because as we talked about when we described that vaccine, that’s a technology that has never produced a licensed vaccine to this point.
Rick: Not yet. Now, the caveats we don’t know about the adenovirus vaccine — one is, do people that are immunocompromised develop a response? Is it safe in women that are pregnant? What about individuals over the ages of 55 — because one of the studies suggested that at least the antibody response wasn’t quite as robust — and do they need a single dose or multiple doses? Are there differences in different ethnicities as well? These are the things that phase III studies will help us ascertain.
Elizabeth: Let us mention — which we did not mention, of course — that these are both published in The Lancet. Let’s turn to the British Medical Journal. This is a look at the impact of physical distancing on reducing the spread of the current coronavirus.
In this study, they took a look at 149 countries or regions and they said, “Out of five different physical distancing interventions, including closures of schools, workplaces, and public transport, restrictions on mass gatherings and public events, and restrictions on movement — otherwise known as lockdowns — between January 1st and May 30th of this year.” The upshot of the whole thing was that the implementation of any physical distancing intervention was associated with an overall reduction in COVID-19 incidence of 13%.
I also thought this was really interesting because I sort of laughed about it. They additionally observed that the closure of public transport was not associated with any additional reduction in that incidence when these other physical measures were instituted, but of course, it causes me to beg the question of, “Well, who’s on public transport if the whole place is on lockdown?”
Rick: Elizabeth, you’re right. Once you have those lockdown measures, there are actually fewer people on public transport. What do you think about the implications for either policy or practice? How do we take this information and then use it?
Elizabeth: That’s such a good question and I’m not really sure about that. This is going to foreshadow what we’re going to talk about a little bit, about transmission among children. But the school closures, the workplace closures, and I think especially … It would be interesting to have them rank order these. They did attempt to do that. They attempted to look at sequential use of these different physical distancing measures among all these different populations and they weren’t able to really come to any conclusions about which was the most efficacious in reducing transmission.
I would say that some of the information that’s coming out right now in the United States seems to suggest that perhaps it’s just the mass gatherings or big gatherings of people.
Rick: One of the things I appreciate about this study is, prior to the study, all we had were modeling studies that suggested that physical distancing would decrease the incidence of COVID infection. This is a real-life observational study from 149 different countries and it’s pretty consistent in that physical distancing — not in a model, but in real life — has actually reduced the incidence of COVID infections.
Elizabeth: Let’s turn to the Journal of the American Medical Association speaking about physical barriers in this case, a look at the association between universal masking in a healthcare system and SARS-CoV-2 positivity among healthcare workers.
Rick: This is incredibly important, not because healthcare workers are any more important than anybody else, but the healthcare workers are caring for individuals that have COVID infection, and we want to make sure we do everything we can to protect them so they’re available to care for others.
This was a study done at the Mass General-Brigham healthcare system. It’s the largest healthcare system in Massachusetts. It has 12 hospitals, more than 75,000 employees. To protect their employees, they instituted a multi-prong infection reduction strategy. Probably the major thing was universal masking, not only the healthcare workers wearing masks, but also the patients as well.
To try to determine whether this was an effective strategy, they looked at the percentage of healthcare workers that tested positive. Now, did they test everybody? No. These were individuals that had symptoms — that’s what prompted them to get tested — but they had a group of healthcare workers before they implemented you wearing mask. First, it was the healthcare workers, and afterwards the patients, and then afterwards to see the effects.
Prior to implementing the universal masking, the positivity rate went from 0% up to 21%. Then after they implemented it, it kind of flattened out — until universal masking in both populations — down to 11%. Really good evidence that it really makes a difference.
Elizabeth: What do you think about the practicality of having patients mask whenever a healthcare worker comes into the room?
Rick: There are settings where that’s not possible or probably not even necessary. For the ICU, for example, when someone’s intubated, because they’re not breathing respiratory droplets. But throughout the hospital, it’s actually not a bad practice.
If I’m a patient in the hospital, I don’t want to get COVID infection and I would want to wear a mask. But from the healthcare workers’ perspective, it also protects them as well, so I actually think for the vast majority of patients it’s a viable practice.
Elizabeth: You would say that then the healthcare environment needs to provide those masks if patients come in without them?
Rick: Absolutely. If that helps to cut the positivity rate of COVID infection by half, that’s a terrific return on investment.
Elizabeth: Okay. Let’s finally turn then to an early release from the Centers for Disease Control and Prevention of Emerging Infectious Diseases. This was the contact tracing during the coronavirus outbreak in South Korea.
In this report, they analyzed data for almost 60,000 contacts of 5,700+ coronavirus disease index patients reported in South Korea, as we know — just in the first 3 months of 2020 since their outbreak, and I have to say I’m feeling rather envious — is under control.
Of their 10,592 household contacts, just shy of 12% had COVID-19. Of the just shy of 50,000 non-household contacts, about 2% had COVID-19.
One of the things that they did in here was they grouped their index patients by age, and this was really by decades of life — from 0 to 9 years of age and so forth — until they got to greater than 80 years.
They were able to determine, COVID-19 in that 12% of household contacts, that the rates were higher for contacts of children than adults. The highest COVID-19 rate, which was about 19% for household contacts of school-age children, and the lowest only 5.3% for household contacts of children 0 to 9 years of age.
They found this during the middle of this school closure, so they’re speculating now what some of the factors might be relative to this. What people are interpreting this data to mean, or to help inform, is this whole issue of, “Well, all right, how much are kids really responsible for transmission and what about this really gigantic domestic issue we’re looking at right now, which is the possibility of school opening?”
Rick: A couple of things about this study I found particularly virtuous. One is over 5,700 index cases and about 60,000 of their contacts, and they monitor these for 10 days to see if they develop symptoms, so it’s a pretty large study.
Again, it confirms that even among household contacts, the risk of transmitting infection is pretty low, about 12%, about 1 in 8 individuals, and for non-household contacts the infectivity rate’s even lower. It’s 2%. That’s really pretty low.
As you highlight, there may be some age differences. It’s interesting that the instance of positivity when the index case was 10 to 19 was really not much different than those that were from 60 to 80 years old. It was 17% to 18%, but it’s bracketed on those that are younger and those that are a little bit older, where it was less.
It may just be how long you hang around someone at the house and whether you’re actually using PPE and social distancing or not. Because, as you know, the group that you’re highlighting — the school-aged kids aged 10 to 19 — A) they’re not usually likely to social distance and their compliance with PPE is really not very good. This may have less to do with ages, more to do with cumulative exposures.
Elizabeth: Would that be your take-home then, that if people are thinking seriously about reopening schools, that the implementation of PPE is going to be really critical?
Rick: I think, again, maintaining social distancing and PPE among all age groups. Previous studies have shown that there’s not any one group that’s particularly more or less likely to get infected. It is related to exposure: how frequent, how close, what the duration is. Then finally, the severity of the disease is worse in older individuals, but infectivity doesn’t appear to be different across different age groups.
Elizabeth: On that note, that’s a look at this week’s medical headlines from Texas Tech. I’m Elizabeth Tracey.
Rick: And I’m Rick Lange. Y’all listen up and make healthy choices.
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