COVID-19 Vaccine Facts

Learn the facts about COVID-19 vaccines, including common questions related to vaccinating kids and what’s safe for those who have been vaccinated. Get more facts by visiting the Children’s Health COVID-19 hub.
COVID-19 Vaccine Facts
Featured Speaker:
Jeffrey Kahn, MD
Dr. Kahn is board certified by the American Board of Pediatrics and Pediatric Infectious Diseases. He earned his medical degree from State University of New York Downstate College of Medicine, completed his residency in pediatrics at Yale New Haven Hospital and spent three years in a pediatric infectious diseases fellowship at Yale University School of Medicine.

Learn more about Dr. Kahn

Prakash Chandran: This Children's Health Checkup COVID-19 podcast was recorded on June 10th, 2021. The COVID-19 vaccine had been FDA approved for anyone over the age of 16 and on May 10th, 2021, the FDA granted emergency use authorization for the Pfizer vaccine to also include ages 12 to 15. Well, this is obviously an exciting step to protect more people from COVID-19. Parents may have questions or feel uncertain about getting their child vaccinated. Today, we'll learn the facts about COVID-19 vaccines, including common questions related to vaccinating kids and what's safe for those who have been vaccinated. This is Children's Health Checkup, where we answer parents’ most common questions about raising healthy and happy kids. Here to cover COVID-19 vaccine facts is our expert, Dr. Jeffrey Khan, the Director of Infectious Disease at Children's Health and a professor at UT Southwestern. So Dr. Khan, it's great to have you here today. Let's start with a question that really is on every parent's mind: Is the COVID-19 vaccine safe for our children?

Dr. Jeffrey Kahn: Well in a word, yes. We have a lot of experience with this vaccine now. As you mentioned, this, the Pfizer vaccine, was recently approved for children, 12 years of age and older. And the clinical trials in this age group and our vast experience with this vaccine so far show that it's actually very safe and of course, very effective.

Prakash Chandran: Okay. But one of the things that I had heard is that COVID-19 doesn't affect children like it does, for example, an older demographic. So, why should parents vaccinate their children if their risk is low, and what are the benefits of doing so?

Dr. Jeffrey Kahn: For many reasons, one of which it's true that children are at lower risk for severe disease due to COVID as compared to older adults or compared to individuals with underlying risk factors. However, they're still prone to infection and some children in fact, do get sick. There was a CDC report published recently that looked at an increasing trend of hospitalizations in children 12 to 17 years of age. So that points to the fact that children can and do get sick. And now we run a very effective vaccine to protect them, but the important thing here as a society, if we want to get the virus under control, we have to immunize as many people as possible. And we do this other vaccines. And to me, one of the great examples of this is the rebel vaccine. So every child should get the MMR vaccines. The R is for rubella. Well, what is rubella? Rubella is a virus that for the most part causes a mild disease one major exception. And that major exception is that rubella can cause infections in a fetus. That's developing a pregnant woman and somebody called congenital rubella syndrome. And if a pregnant woman who is not immune to the rubella gets rubella, her fetus can develop brain defects, heart defects, blindness. And strategy that we've taken in this country it's done in many other countries of course, is that we immunize everybody, including boys. Well, boys really are not at risk for any severe infection due to rubella. But we have to immunize everybody if we want to protect pregnant women against being exposed and that strategy has worked remarkably well. We don't see congenital rubella syndrome. In this country, I've been a physician now for almost 30 years and I've seen three cases. And all of these cases were from abroad. So this is a strategy that has worked wonders that we immunized as many people as possible. And we protect the herd. We protect pregnant women. If we didn't immunize boys against rubella, what would happen is we'd have half the population that's susceptible to rubella. If rubella was introduced into our communities, it would spread pretty quickly because half of the individuals are not immune. And then the virus would find a pregnant woman and then lead to this awful congenital infection. So think about immunizations. We're not just thinking about the individual. Of course, that's very important, but we're thinking about society as a whole. And we've been remarkably successful in eliminating a lot of these viruses that in most cases only cause severe disease in small percentage of individuals. Polio is an example of that. Only one in 150 people who get infected with polio actually get paralytic disease, but we immunize everybody. We've got written the virus, you know, ask yourself, when was the last time you saw a case of polio. So, these types of strategies work remarkably well, and to get this virus under control, we have to continue with these types of strategies.

Prakash Chandran: Absolutely. And you're making such an important point. I think one thing that people may not realize is that all of these viruses exist in the world. And. They are looking for hosts and the more people that are protected, that's less hosts for the virus to go and infect and then ultimately get to the people that are most susceptible. So I think it's important to realize that you're not, again, as you've said, doing it for yourself, but the greater good for everyone else, because whether you like it or not, these viruses are out there and they're going to be there. So the best strategy is to get everyone protected. Wouldn't you say?

Dr. Jeffrey Kahn: I couldn't agree with you more. This is a strategy that has worked against some horrible viruses that have circulated in the past smallpox, the only virus that's been officially eradicated from the world. I mentioned polio measles, very unusual mumps. It talks about rubella. And so the list goes on and on. And these are remarkably effective tools. You don't have to go back too far in history to see outbreaks and epidemics in the United States due to some of the viruses I just mentioned, and they wreaked havoc. Parents were terrified that their child is going to get polio or measles or one of these other diseases. To a certain extent, vaccines are a victim of their own success. We don't see these, horrible diseases anymore and people aren't scared of them. Well, maybe they're not as proactive when it comes to vaccination, but they should be. The reason that you don't see these horrible diseases is because we have really great vaccines that work quite well.

Prakash Chandran: Yeah, that makes a lot of sense to me, Dr. Khan. You know, one of the things that I wanted to ask you about was the mutation of the COVID-19 Iris. If you get the COVID-19 vaccine or your child gets it, will they still be susceptible? If they come into contact with one of these mutated strains?

Dr. Jeffrey Kahn: So right now we have experienced in this country with three different vaccines. We have the Moderna vaccine, the Pfizer vaccine. Those are both based on MRNA and the Johnson and Johnson vaccine, which is a different platform based on Novartis. All the data that we have so far, which is really focused on the two RNA vaccines show that these vaccines, thankfully, are still effective in producing protective immunity against the variants. Variants tend to be a moving target. They're not going to stop. The virus is not going to stop mutating and certainly there's an anticipation or a reality, perhaps that we're going to identify more variants as we move through the pandemic. But right now it seems that the vaccines are effective; protecting individuals from infection and in those individuals who have been vaccinated, who actually do get sick with a variant, the disease tends to be quite mild. So although the vaccine may not prevent infection with one of the variants, it certainly protects against severe disease.

Prakash Chandran: Okay. That's helpful. You know, moving back to, if the vaccine is safe for children, you there's children out there with chronic health conditions. So are there any cases where children with chronic conditions or otherwise shouldn't get the vaccine?

Dr. Jeffrey Kahn: Well, the only real contraindication, if you will, would be for individuals who have or a severe allergic reaction to any of the components of the vaccine, that's going to be very unusual because this is a relatively new platform for vaccines. As far as kids with chronic or underlying medical conditions, you know, these children are probably going to be much greater risk for severe disease due to COVID then otherwise healthy children. All the more reason to get these children immunized. So if you have a child or grandchild who is eligible to get vaccinated, and they have underlying medical problems that may put them at high risk for severe, COVID go ahead and get them immunized. And by the way immunize any eligible individual in the family, because we know that the COVID virus can spread quite readily the household.

Prakash Chandran: Yeah, you don't one thing that I've heard that might be a myth here is that you know, children who have already gotten COVID-19 don't need to get the vaccine because they already have those antibodies. Can you speak to that?

Dr. Jeffrey Kahn: Sure. One of the striking things about the Moderna and the Pfizer vaccines, MRNA vaccines is they produce a really dramatically robust immune response. And in fact, the immune response that's produced or induced by these vaccines is actually greater than the immune response induced by natural infection. So to a large extent, it seems that the vaccines will provide an individual with a much greater immunity than natural infection. On the other hand, we should remember that even individuals who have already had COVID are still eligible to get the vaccine. And that vaccine after natural infection would only boost your immune response and presumably add to the durability of the vaccine.

Prakash Chandran: Got it. So I just want to move into just more general questions about COVID-19 in the vaccine. What are some common myths or concerns that you've heard about the vaccine and are they true?

Dr. Jeffrey Kahn: So there are a whole bunch of myths going out there and, but let me just address a few of them. One is that you can get COVID from the vaccine. That myth has been out there. The vaccine only contains one portion of the virus. It doesn't contain the whole virus, so there's no way you can get COVID from the vaccine. The vaccine is based on this technology called MRNA and without getting into a lot of details. This vaccine cannot alter your DNA and been discussion out there about this. That's a complete myth. It doesn't alter your DNA. It cannot alter your DNA the last myths that I've been hearing, which is among the most baffling I've heard. Okay. About this vaccine or any vaccine the myth is that the vaccine can cause infertility and it's completely untrue. There's no data to support that at all, but why I find it so baffling is that these two vaccines, the two MRNA vaccines were approved for use in the United States in December. And it wasn't until late December, early January that the vaccine campaign really ramped up. And I started hearing about this fertility issue in January and February. And first question I asked myself, of course, is. Yeah. How could we possibly know that the vaccine causes infertility if it's only been in use for a month or two? So that didn't make any sense. There's no evidence in the clinical trials that it causes infertility. It's a complete myth. And on a, you know, on a personal note, I have two daughters who were in their twenties. I strongly urge them to get the vaccine and they did get the vaccine. And I'm not at all concerned about infertility.

Prakash Chandran: Yeah, that's very helpful to hear, you know, one of the things that I've heard related to that is that there really hasn't been any true longitudinal studies these vaccines. So how might you respond to people that are saying that?

Dr. Jeffrey Kahn: It's highly unlikely. That they're going to be any long-term side effects from this. We know there are certain side effects related to other vaccines. Those side effects tend to occur shortly after the vaccine is administered. Not years later. The only thing I should, comment on is that you have to weigh the risks and the benefits of any action when it comes to this. And so, you know, when you think about the risk and the benefit, well, the benefit of getting the vaccine is of course you're going to be protected against COVID. As we discussed a few moments ago, you know, there, people can get very sick from COVID, including children. You know, the risk of the vaccine is very low. When you look at all the facts, quite clear, at least at this point that these are quite safe vaccines. One of the other things I've been hearing is that, this whole thing about, well, it's an experimental vaccine, and we don't really know, and I'm waiting to hear more results. Well, right now we are approaching, nearly 300 million doses of vaccine that's been given in this country. I mean, that's an extraordinary number. So now we have this mountain of information about the vaccine that we didn't have just six months ago. The logic starts to fall apart when you start looking at what we know about this vaccine and what we know about other vaccines. Again, if there's going to be an adverse event, it's typically in the immediate time after the administration of the vaccine.

Prakash Chandran: Yeah. And another thing that I had been hearing from people is that, you know what, this doesn't have full FDA approval. Therefore I'm just. You know, waiting until that happens. A lot of people don't realize that the minimum bar for FDA approval for most vaccines is only 50% efficacy. And these vaccines that are coming out are much higher than that. Isn't that true? Dr. Khan?

Dr. Jeffrey Kahn: Absolutely true. I've heard this before, and I've talked to parents and to children about this and the friends and colleagues and the. Clinical trials that went into approving the vaccine were very, very robust clinical trials and they included numbers of subjects that are typically used for vaccine approval for other diseases. What accelerated the approval was the emergency use authorization. But what also accelerated was the fact that we were in the middle of the pandemic. So we weren't waiting around for disease to show up. It was already present and therefore clinical trials can be conducted in setting where there's lots of virus circulating. So we got a lot of information in a very short period of time. And so no, there were no shortcuts taken for the approval of this vaccine. And now that they've been approved, by emergency use authorization. We're continuing to find out that they're safe. And as you mentioned highly effective.

Prakash Chandran: Yeah. I wanted to move on to a clarifying point around if it's possible to contract COVID-19 after the vaccine. And one point of confusion that I'd love for you to clarify is that some people have said, well, this actually doesn't prevent you from getting COVID. It just prevents serious side effects or death. And then others have said, no, this actually prevents against COVID-19 and you won't contract it. So maybe you can speak to that. What exactly it protects you from. And if it's possible that you contract it after being vaccinated.

Dr. Jeffrey Kahn: Right. So the two issues here if we try to sort this out would be one is, can immunized individuals get infected and maybe they have asymptomatic infection or they're just a carrier, if you will, whether they get disease. Now, of course, the ultimate goal for a vaccine if you've gotten the vaccine, you cannot get infected, but if you can't achieve that, then you certainly want a vaccine that prevents disease. And that's really the ultimate goal here is to prevent disease. And what we know with these vaccines that they do. Both really prevent you from getting infected. In other words, if you take somebody who's been immunized they're out in the community and there's virus circling the community and you swab them on a regular basis, they don't seem to acquire the virus. And certainly we know that even if you do acquire the virus, that you're far less likely to get severe disease. We know that these vaccines are 94% effective and that's in the vaccine trials were typically against symptomatic disease. So yes, they're going to be five or six percent of people who are immunized to still may get infected. But when you drill down on the data, the data clearly show that these vaccines are wonderfully effective against preventing disease. And I think that’s profound statement in the sense that with these vaccines, you're a likely, never going to get infected. And even if you do get infected you have a very low risk developing severe disease than if you didn't get vaccinated.

Prakash Chandran: So just moving back to children in vaccination, let's say you are a parent that is fully vaccinated and you have a child in your household who is not vaccinated. Are there any precautions or considerations that you need to be mindful of?

Dr. Jeffrey Kahn: That's a daunting question. And a lot of parents with young children are dealing with this right now. So as you mentioned in your question, anybody in the household who is 12 years of age or older should get vaccinated. Now, of course, there are families with young children. What do you do? It doesn't seem that vaccinated individuals can spread the virus all that much. You know, certainly if I had young children in my household, I would be cautious where I'm going to reduce my chance of being exposed to the virus. And certainly that would be true the child. So it's those types of precautions continue to wear a mask outside. And, you know, in many states the mask mandates are falling away. Right. But that doesn't mean you still can't wear a mask and practice social distancing and hand-washing and all these other behaviors that we became very used to last year. If you live in a household with somebody who can't get vaccinated, then you should go, you know, continue to practice those particular types of behaviors. And the other comment should be that even if you have somebody in your household who may be on, immunosuppressive therapy, for example, if they're a transplant patient or transplant recipient, they may not have responded to the vaccine. So all the more reason to get everybody around that individual who may not have an immune response to the vaccine, everybody around them vaccinated to greatly reduce the risk to that particular individual.

Prakash Chandran: so Dr. Khan, just before we sign off today, is there a central message that you would like to leave our parent listeners with?

Dr. Jeffrey Kahn: I mean, can't emphasize this enough. Get your kids vaccinated if they're eligible, but we're going to find out maybe towards the end of the summer or in the fall is that we may see vaccine eligibility reduced to a much younger ages. And that's because thorough investigations have found that these vaccines are safe in younger ages. Go ahead and get vaccinated. This is the only way that we're going to get this virus under control as a society. We have to immunize all eligible individuals or the virus is going to continue to circulate. It's going to continue mutate; new variants are going to emerge. And one of the things that keeps me up at night is that if we don't get this virus under control, a variant may merge that is resistant to the immunity induced by the vaccines. And then we're back to square one. So, that's the message. We are not out of this yet, we should take advantage of the tools that we have. And biggest tool that we have in our toolbox right now are vaccines.

Prakash Chandran: Well, Dr. Khan, I think that is the perfect message to end on. Thank you so much for your time today. Thank you all for listening to this episode of Children's Health Checkup, to find out more information about the COVID-19 vaccine and how it affects children, please visit If you found this podcast helpful, please rate and review or share the episode and please follow Children's Health on your social channels. This has been Children's Health Checkup from Children's Health. Thanks so much. And we'll talk next time.