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Prakash Chandran (Host): This COVID-19 podcast was recorded on September 14th, 2021. This is Children's Health Checkup where we answer parents most common questions about raising healthy and happy kids. COVID-19 has been in America for almost two years. And in that time, variants have developed. Here with us to discuss is Dr. Jeffrey Kahn, Director of Infectious Disease at Children's Health and Professor at UT Southwestern. We'll be discussing the COVID-19 variants, vaccines and how families can stay healthy. This is Children's Health Checkup. My name is Prakash Chandran. And so Dr. Khan, great to have you here today.

Let's just start by understanding a little bit more about variants themselves. Can you talk about what variants of a virus are?

Jeffrey Kahn, MD (Guest): Certainly. So viruses as they are transmitted from individual to individual will change during that progression. And the more that virus travels from individual to individual, the more is apt to changing and basically adapting to the host and also trying to evade the immune system of the host. And this happens with all viruses, not just the COVID virus. This happens with flu viruses and measles other types of viruses. And this is something that's been known for a very, very long time. And in fact, it's quite predictable. What we've had now the SARS COV 2 virus that caused COVID since it's emerged and spread worldwide, because it's infected so many individuals and gone through so many rounds of replication, these more fit viruses, if you will, begin to emerge. Those viruses or those variants of the virus that has some selective advantage over its predecessor will now out-compete the other viruses and that's basically the dynamics of the emergence of viral variants.

Host: Okay. Understood. And so, you know, I want to kind of talk about some of the current variants that parents should be aware of. And the one we're hearing about most is the Delta variant. So, if I'm to understand correctly, this Delta variant has kind of out competed with other mutations or variations of the virus and just happens to be the most widespread today. Is that correct?

Dr. Kahn: That's correct. The Delta variant has been around for almost a year now and was at very low levels and then entered different populations and then it really took off. So, before Delta virus made a big impact in the United States, it was identified in other countries. And in those other countries, Scotland is an example. Israel, another example. Once it took a foothold in that country, it quickly over the matter of weeks or a month or two, sort of took over as the predominant strain. And in fact, that's what's happened here in the United States. In early May, the Delta variant was a very small percentage of the virus that was circulating here in the United States.

And as of the latest data available from the CDC now, greater than 95% of the viruses that are circulating right now are the Delta variant, and that's independent of where you look in the United States. So, if you're looking in the Southeast or the Northwest or the Northeast, it doesn't really matter, it's the Delta variant. So,it has out competed the other variants. That is not to say that these other variants aren't still out there lurking somewhere. But at this moment in time, it's the Delta variant that has really taking over the COVID landscape.

Host: Speaking of these other variants, can you speak to what some of those are?

Dr. Kahn: So, we know that there was initially a variant that emerged in the UK and then a variant in South Africa. And it was a variant from Brazil and the World Health Organization sort of clarify a lot of this and really not to point to a specific country as the origin of these. These were perhaps countries where they were first described that misled, the origin went to this other nomenclature where they now name the variants by Greek letters to say. And so now we have the alpha variant, the beta variant, gamma, Delta, and so on. And so some of these variants, we were very used to them. We were very familiar with early in the pandemic, the alpha variant, for example, the one that was initially identified in the UK.

Now there are of course newer variants that are emerging that have somewhat, slightly different properties than Delta, but have also evolved in a way that may cause some concern. Fortunately, a lot of these variants, this Mu variant that's drawn some attention now, it's still a very low levels in the United States and elsewhere.

And hopefully it will remain that way. But I think the bottom line here is that there are many variants that are out there. I suspect that more variants may emerge. And it's difficult to predict right now, which one of these variants will be the predominant variant again, in a location at any point in time in the future.

So right now it's Delta. It's hard to predict what the dominant variant in the United States will be in December. There may be multiple variants that depending on where you are in the United States. So, this is something that we have to keep an eye on.

Host: Yes, absolutely. You know, speaking of these COVID-19 variants, I imagine that they are more dangerous than the original COVID-19 virus for all of the reasons that you mentioned, right? The virus mutates to try to dodge, maybe some of the things that are fighting against it. Is that a true statement?

Dr. Kahn: Well, this is a sort of a fundamental principle in virology and again, true for all viruses. And it really has to do with what's called fitness. So, yes the virus will mutate to elude the immunity of the host and of course, now we have vaccines, so many people are vaccinated, so the viruses are trying to escape or sidestep that immunity that's induced by the vaccine.

Now the vaccine, at least the Pfizer and the Moderna vaccines are based solely on what's called the spike protein. The spike protein of the virus is necessary to bind to the human cells. And in fact, our immune response, the antibodies that we produce against the virus based on the vaccine is that the antibodies will bind to that spike protein, by the way, the J and J vaccine also has the spike component, but it's a different platform. So, now we have antibodies targeted against the spike protein. The spike protein has to bind to cells. So, now the virus starts changing it's spike protein. And here's what happens when the concept of fitness comes in so the virus can only mutate so much before the spike protein can no longer bind to the human cell. So, it's not an infinite race, if you will, the virus can start changing it's spike protein, but it can only change it so much that it can still bind to the human cell. And hopefully it will get to a point where we have an immune response to just about every one of the or most of the potential mutations, such that the virus can no longer mutate to escape the immunity. I don't think we're nowhere close to that right now. And we'll see what happens, but there is a possibility that as we push this virus more and more to mutate, it will become less fit. And hopefully it's certainly that is the, hope that we'll be able to conquer this pandemic using this sort of immune strategy.

Host: One question I hear all the time and I even ask myself, is, are COVID-19 vaccines even effective against these variants? Because you hear about breakthrough cases where someone is vaccinated and they still get infected with COVID. So can you speak to the vaccines efficacy against these variants?

Dr. Kahn: So there's variety of ways that we can define vaccine effectiveness. The best vaccine imaginable, would be a vaccine that prevents infection. And we have examples of that. The measles vaccine, for example, you get immunized against measles and you're basically protected from infection. Other vaccines and maybe a lower tier, if you will, will prevent you from getting really sick.

And I think that's where the COVID vaccines fall in, in regards to the Delta variant. So, what we do know is yes, there are breakthrough infections, but the vast majority of the breakthrough infections tend to be very mild disease. And there are lots of data that are out there. Several publications recently from the CDC that show that yes, the effectiveness the vaccine, as far as preventing infection from the Delta variant is lower than the effectiveness of that vaccine in protecting and preventing infection from the previous variants. However, the vaccines are still very effective against the Delta variant in preventing severe disease. So, what we're seeing now is these quote unquote "breakthrough infections" are basically mild disease.

It's a cold or maybe a mild flu like illness. What these vaccines are doing, it's keeping people out of the hospital. It's keeping them from evolving into very serious illness, wheee they require supplemental oxygen or other respiratory support, hospitalization, ICU, so to speak. So, in that regard, these are still fantastic vaccines as far as preventing severe infection.

Host: Yes. And one of the things that I did hear is that a lot of people that were in the hospital right now were unvaccinated like 95% of them. Is that true? Had you heard that?

Dr. Kahn: Yes, that is in fact true. To a very large extent what we're seeing right now in the hospital, if you're just looking at hospitalized patients, that's really an epidemic of the unvaccinated. Now, unfortunately you know, the vaccines right now are only approved for the age of 12 and over. So, so children under the age of 12 are basically unprotected and there are studies ongoing right now to to look at the vaccine efficacy and safety in younger children.

But right now we have significant proportion of the population, those kids, or less than 12 years of age, who are not eligible to get vaccinated. Fortunately the disease in children tend to be somewhat less severe than a disease in adults, but nonetheless, there are children out there with underlying medical problems who are running into a lot of problems when they're getting infected with COVID. And in fact, we're seeing that right now in our hospitals.

Host: Yeah, I was just going to ask you about that. A lot of people that might be listening to this are wondering how can I keep my family healthy and safe from these COVID-19 variants? And there are a lot of parents, myself included that don't have children that are of the eligible age. So do you have any tips or advice for how we can keep our family safe from these variants?

Dr. Kahn: So I would start by answering that question by stating something I think it's very important for parents to understand. And that is that your greatest risk of getting infected with COVID is having a household contact, who's got COVID. We know that the virus spreads very easily in households, and if you have somebody in your household, who's too young to be vaccinated or may not respond to a vaccine because they're immunosuppressed, the number one thing you should do is to make sure that everybody in that household who is eligible to be immunized, gets immunized. So that is the most important thing.

Cause if the virus enters the household, it's going to find the unvaccinated individuals. Or the people who are particularly prone to COVID. So that's a number one. And of course, now we know that even vaccinated people can get infected and may shed virus, may shed infectious virus. So, for people who have young children at home or other people who may be susceptible to COVID when you go out in the real world, be mindful of the fact that you may unwittingly be bringing COVID home.

You may not even be symptomatic and bring COVID home and therefore expose family members to the virus. So when you're out in public, wear a mask and try to do the types of things that we were doing very well about a year ago, and that it was, you know, social distancing, hand-washing very, very important and being mindful of the people around you and be mindful of the places that you go, you know, being outdoors in an open park, that's probably a very low risk, but being in a crowded concert, that's a different story. And now we're seeing, you know, the lots of gatherings and public gatherings at concerts and football games and other sporting events, a lot of people not wearing masks. So, be mindful of that, that even though you're vaccinated, you may be protected against symptomatic infection. You still may carry the virus home. So again, doing these sort of low tech types of things, mask wearing, hand washing, social distancing can really help stop or prevent or certainly lower the likelihood that you're going to bring home the virus and spread it to others in your household.

Host: Dr. Khan, very informative conversation today. Is there anything else that you would like to leave with parents or the audience that's listening before we close today?

Dr. Kahn: Yeah, I think the issue again with the variants, I think we have to keep lot of attention on the variants and from a public health perspective, the longer that we allow the virus to circulate in the population, the higher, the likelihood that new variants are going to emerge. And my fear is and public health officials, infectious disease specialists, and others; our fear is that there's going to be a variant that emerges that may sidestep the immunity induced by the current vaccines. And if that's the case, then we're back to square one. All the more reason to try to get this virus, the spread of this virus under control.

The variants are the wildcards. They're going to dictate how long we're dealing with this. And as a population and as a nation and as a community; the way to prevent these variants from emerging is to get as many people vaccinated as possible. I dread to think that we may look back on the opportunity that we had now, and that we missed this opportunity because in months from now, or even a year from now, there's a variant that emerges that will really set us back considerably. So again, this is the public health pitch to go ahead and get as many people who are eligible to get vaccinated and get them vaccinated.

Host: Absolutely. And just to be clear, these variants come about or they mutate because they have hosts and if you are un-vaccinated, then you are a great specimen for that COVID-19 virus to mutate and to change. And the more people it can hop to the higher, the likelihood that a variation will be created. Isn't the case?

Dr. Kahn: And it is absolutely correct. And you know, we know this not just from COVID. We know this from other viruses I mentioned earlier in the podcast. We know this, we have this knowledge. And it's indisputable. And I think it's important for the public to realize that we have an opportunity now to really get this under control. And if we'd let this opportunity go, we may be very regretful.

Host: Well Dr. Khan again, this has been truly informative, and I really appreciate your time today.

Dr. Kahn: It's my pleasure.

Host: Thank you for listening to Children's Health Checkup. Head to children's.com/COVID-19 for more information. If you found this podcast helpful, please rate and review or share the episode and please follow Children's Health on your social channels. Thank you again for listening and we'll talk next time.