A Formidable Defense Against Infectious Diseases | Vital Science: S2, E02
Welcome back to Vital Science in episode two of our series on vaccines. Last month, Dr. Sarah Gould gave us a little background on the history of infectious disease before diving into the origins of vaccine therapeutics and the challenges of developing a safe and effective defense against viruses like COVID. If you missed that episode, I encourage you to check out our Vital Science podcast homepage, criver.com/vitalscience. You can also find us on Apple Podcast, Stitcher, Spotify, or anywhere you access your favorite podcasts. Today's episode is especially timely as we all prepare to enter another flu season under the continued threat of COVID-19.
We may take the usual precautions against infections, wash our hands, wear our masks, practice social distancing. We'll probably take our body's natural defenses for granted. Dr. Christina Satterwhite is here to shed some light on the complex and extraordinary nature of the immune system.
In this episode, she'll help us to understand how our body's natural barriers and cellular components work in concert to fend off pathogens without us even being aware. Ever wonder why it's so highly recommended that you get a flu shot every year. Stay tuned for an insightful answer, as one of our immunology experts at Charles River, Dr. Satterwhite is well versed in the science of infectious disease and therapies that enhance the immune response to prevent illness or lessen its effects. She and Chris will talk about different vaccine types, how they work, and some of the therapies currently in development.
- I'm here with Dr. Christina Satterwhite, senior director of global lab services from Charles River. Tina, welcome to Vital Science. Before we get into how vaccines work, can you walk us through how our immune system works and how the body defends against infection? - Yes, Chris, I would be happy to do that.
And currently, I mean, we are talking about viruses in this country every single day. So I feel like explaining the basics of the immune system and why vaccines really are integral, and to ensuring that we're protected is very important for everyone to understand. So what I'll do is I'll start with how the immune system essentially works in layers. You can almost think of it like the toys we pull off the different layers of the hat.
So number one is the skin. The skin is your very first barrier to any kind of pathogen. Again, we're talking about viruses or bacteria.
So if a pathogen gets past your skin, then the second layer would be the mucosa that you have in your nasal passages or in your throat, you have earwax in your ears to keep out pathogens. If essentially the pathogen gets past all of those first and second barriers, then you get into really the immune system. And typically, historically the way that it's described is you have a non-specific or what we call the innate immune system versus a specific or adaptive immune system.
So the immune system is really made up of a lot of different types of cells. And so what I'll do first is talk about our innate immune system. So essentially, your innate immune system, when it comes to within the body is again, the first line of defense, because we have a lot of different kinds of cells within our immune system, such as macrophages. And if you think about what macrophages do, the best analogy is they go in and they really almost like a Pac-Man.
They go in and they eat up particles of viruses and bacteria. And they try to go ahead and clear that from your body before there's any chance of them going any further. Another type of cell in your innate immune system is natural killer cells. And they're very important in essentially attacking viruses and cancer.
They're actually little cells that are equipped to go in and kill anything that the body sees as not self. The second line of defense is really your specific or your adaptive immunity. And this is really where we have a lot of different cell types that really contribute to fighting against not only bacteria and viruses, but also cancer. So this portion of your immune system is made up of different cells.
And what you typically, when you hear individuals talk about it, they're gonna talk about your white blood cells. So your white blood cells are encompassed by lymphocytes, and all of them initially start within the bone marrow and then they move out of the bone marrow and then you have what you call T-cells and B-cells, and then come out and are part of the defense against any kind of attack on your body. So when we talk about the difference between T-cells and B-cells, B-cells are part of your humoral immunity, and I can explain that because that really means that you have these B-cells that are produced by plasma cells and they are a component of how antibodies are being produced. And so when you are exposed to, let's just say, a virus, what happens is that your B-cells are activated and they go ahead and they generate IgM and IgG antibodies.
And those antibodies allow you to essentially clear the virus. And so that response usually though for the B-cells takes between seven to 14 days, and really the IgG response, which is your memory response. So what that means when you're talking about B-cells is that you develop these antibodies over a period of time. Sometimes they can last for six months, but sometimes they can last for much, much longer years. And what'll happen is when that same virus is seen by our immune system, then the B-cells will go in and clear those viruses. So that's a lot of why currently you hear about the fact that you have to stay quarantined if you're talking about COVID for 14 days, is that they really want to make sure that you mount these responses from your immune system.
So for example, if we're talking about those antibodies, then they want to make sure you have the time to do that, which gets us to the other part of our immune system which is the T-cell responses. And your T-cell responses essentially also have a memory component. And what they do is they also can come in and they recognize that an antigen or a virus is not self, meaning that they're seeing a sequence of a protein or a peptide that doesn't match anything in your body. And so they go ahead and they recognize that, and then they go and attack. So you have actually two components of T-cells one, well, there's actually more than two, but these are the main components of your T-cells.
You have helper T-cells, which are CD4 positive cells. And then you have cytotoxic T-cells. Cytotoxic T-cells can go in and essentially just attack a virus or a bacteria based on that sequence and kill the cell. And really, what they're finding out right now with COVID-19 is that the theory or the thought is that the immunity that individuals are acquiring after being exposed is more from T-cells and B-cells. There's quite a few papers that have come out recently about that.
But again, it's really early days in trying to figure out exactly how that immune response to that particular virus is mounted. So I just wanted to make sure I kind of gave you guys an overview of how those differenT-cell types work within our immune system to really fight off any kind of potential threat that will make us sick. And so, as we move through and talk a little bit more, there's gonna be some important terms that you need to understand, which is when we're talking about antigens, those antigens that our immune cells recognize as non-self, so it's a sequence of proteins that we don't typically see, or that we haven't seen before, to make that clear. Our immune cells, essentially what they'll do is any kind of, if we're talking about a bacteria, it could be a sugar sequence in a bacteria that they're recognizing and saying, oh, I don't have that sugar sequence, and so I'm gonna go and attack that.
So you could almost want to think of the immune system within your body constantly surveilling and ensuring that if there's any kind of like almost like bad actors within your body, because they got through your barriers, that they're getting rid of them because there's a concept that's really important here, which is the amount of bacteria or the amount of virus that you're exposed to has a direct correlation with how sick you're gonna get. And so the quicker that the immune cells can get in there and really clear out those foreign invaders, then the less sick you'll actually get for visible observable symptoms. And so I think that people need to understand that based on how much you're exposed to has a direct effect on how sick you are. Not only is it that level of exposure and everything, but what happens is, is that even if you're exposed at a very low amount of a certain bacteria or virus, these cells are that specific, that they, and with their memory can essentially, since they've seen that sequence, once in your life, they can attack at any time after that.
So they will always recognize those sequences from what they were exposed to. And so, again, it's important to understand those concepts as we move forward through this discussion. And I think that when I'm talking about the basics of the immune system, I'm hoping that that really helps out, Chris, so that you have a better understanding of what the basic branches of the immune system are, how they work.
And then we can now get a little bit more into vaccines and why they're so important for us to use within drug development, to protect against these essentially foreign invaders that we experience really on a daily basis. I mean, you're exposed to bacteria, you're exposed to viruses daily, and that's why we want to make sure that we have strong immune systems so that we can combat them very quickly and really not get to that level where we're showing clinical observations of illness. - And so far in the news we've heard of so many different types of vaccines coming out for COVID specifically, but even the flu vaccine that we have every year. Help me understand the different types of vaccines that we currently have in the mix for that traditional vaccine work, along with are there any advantages or disadvantages to any of them? - So, Chris, I just wanted to walk you through what the different types are for different vaccines. And so we have what you call live attenuated vaccines, inactivated vaccines, toxoid vaccines, as well as subunit or conjugate vaccines. And so what I'll do is I'll just go into a little bit more detail here about how these vaccines work and what are some of the advantages or disadvantages, and then slightly hit on safety.
So some of the vaccines that have been around the longest are the live attenuated vaccines. These types of vaccines contain whole bacteria or the whole sequence of the virus. And what they do is they weaken the virus or the bacteria, and they do this through different means to essentially accomplish that goal. But these are vaccines that are very, very strong and have really long lasting immunity, and are considered some of the best vaccines that we've generated years and years ago. And so for these types of vaccines, I mean, really the only thing is a lot of them are sometimes manufactured or produced in eggs.
So people that have egg allergies, these would not be very good. They could have an allergic response to them. So it's a question that any provider will ask you as you're going in to get one of these types of vaccines, the measles, mumps and rubella vaccine is definitely shown over the periods of time that it almost at certain points eradicated those particular three types of diseases.
So, these vaccines again, are extremely powerful. A great resource for anyone is to also go to the CDC website because they will talk you through each one of these. So really for the live attenuated, there's really not that many disadvantages, really besides being produced in eggs, they're extremely safe.
They've been given to children and even adults for years and years now, and really been extremely effective in protecting the communities against these types of viruses or bacterial infections. Chris, did you have any other questions around that? - Yeah, I wanted to ask you, you mentioned the safety of it there. There are questions from the general public asking about side effects of the live attenuated vaccines. If I take the nasal flu vaccine, will my child get a fever from that? Is there any science to that? - Yeah, so essentially what the attenuated live viruses are doing is they're weakening essentially that form that you're being given.
So whether you have a nasal route of administration or you have an intramuscular injection, like the MMR, the first thing that happens is they're intended to mount an immune response. So we go back to that discussion we just had about the immune system. And what happens initially is you can get a fever. You can elicit other types of responses as well.
So if you get an intramuscular injection for the MMR, typically what you'll feel is almost like a little bump and it's considered an induration, but really what that little bump is, is those are essentially your immune cells coming to that point and trying to attack that, if it's like at the MMR, it's trying to attack that sequence that it sees again. So I think, but the number one thing to remember about this is those effects are very transient. They typically occur within the first 24 hours. If you ever have any concerns, the number one thing your pediatrician should say, if it's child, but and adult too, they can take Tylenol or ibuprofen so that it really dampens any of those responses that are seen. But again, you do want to get the best immune response you can. So, again, I think hopefully that addressed your question.
So we can move on to inactivated viruses and bacteria. And so some great examples of that would be polio. Polio, the vaccine, has probably been the most effective at completely eradicating a disease.
And another member of this group is Hep A vaccines as well as rabies. And so we all know really at this point for rabies, you bring your dogs in and they get their rabies vaccination, and that's mainly to protect them if they're exposed to like a bat or I think mostly it's bats that carry rabies. So, the difference between the live attenuated vaccines and the inactivated is the virus essentially, let's say it's a virus, you're growing it into cells. This is how you're essentially making it. And then you go ahead and you purify it from the cells. And what you do is you just completely kill it through means of like, maybe it's a chemical mean or it's UV or something like that.
So you're gonna go in and you're just gonna completely kill the ability of that virus to cause you any harm. And what it is though is it does maintain, again, those sequences. And so what they can do is they can take those inactivated viruses or bacteria, and then they can essentially deliver that as a vaccine.
And you utilize that process instead of the attenuated live vaccine. And then your immune system again will mount a response to those sequences and you'll build up that protection. So that's really the difference between the inactivated and the live attenuated. And then what we have is the toxoid type vaccines. So this would be such as diptheria and tetanus. And this is another vaccine that we all get when we're younger.
It's part of the vaccinations that you have to have to essentially go to school. So these type of vaccines are against these type very specific bacterial illnesses. They, again, aim to elicit that immune response against these proteins or toxins.
So the difference here in this type of vaccine is it's they take the antigens from the toxin, and then they chemically inactivate it. So, it's the same as I was just describing, except for the, instead of a virus or bacteria, the source is components of a toxin. And those are chemicals. So, it's a little bit different because it's not derived from protein. And then the last is you have the sub unit. So this is the category where you would have like pertussis B and HPV.
So subunit vaccines include only the components or antigens that best stimulate the immune system. And what that means is that if you're exposed to a virus, it doesn't mean that your immune system responds the same way to all the different components. A really great example of that is with COVID-19 right now where if you hear in the news, they're talking about the different subunits, the spike proteins. And so these are like, there's all these different components of that particular virus and your immune system responds differently to those components.
So for these subunit or conjugate vaccines, what they do is they test all of that and they see which sequence does your immune system respond the strongest to, and they'll look at T-cell immunity, as well as B-cell immunity. And so they're gonna make, and they're gonna engineer that particular vaccine to the sequence that has the strongest response. And an example of that was whooping cough, where after the '70s, they went ahead and they developed a more advanced generation of that vaccine that was really the purified pertussis components. And they saw a lot less side effects. And so when you talk about safety, Chris, this is an example of that.
They had previous versions of the pertussis vaccine, but people would have fever or a lot more swelling at injection sites. And so by changing to this subunit type of vaccine, they were able to get rid of those components that were causing. These are not harmful effects, but they were definitely uncomfortable. And so by doing that, then more people were willing to get the vaccine, because it's not as scary because they don't see these other types of side effects or adverse reactions.
Chris, also, we can talk about Gardasil. Have you heard of Gardasil, Chris? - No, I haven't. - So Gardasil is a vaccine that was made against HPV. So that's human papilloma virus.
So if you're not aware, the human papilloma virus can, once you're exposed to it at a younger age, can result in certain types of cancers. And a lot of these cancers really were quite frequent, especially in women when we're talking about cervical cancer or when any females were exposed to genital warts. It can also result in some of these types of cancers that are the result of being infected by HPV when you're at a young age. So Gardasil is essentially a vaccine that really revolutionized women's health. I mean, if you think about that, right, and even men's health, because sometimes what happens is if you were exposed to HPV as a young adult, later in your life, a lot of cancers that men would get was squamous cell cancers.
They're actually quite deadly. You go ahead and you vaccinate with this drug. I can tell you, this was actually first developed by a company in Australia called CSL. They did a great service to everyone. And what happens with Gardasil is it works to stimulate the immune system to attack four different types of HPV, so 6, 11, 16, and 18. And once it's administered, and it's viral proteins, because again, it's the sub unit type of vaccine.
So it's made up of all the specific sub units of those four types that have been shown to get the best immune response. And essentially, like so far, it's really been effective. So amongst teen girls, infections with HPV types that can cause HPV cancers and genital warts has dropped 86%. Among adult women, infection with HPV types that cause most HPV cancers and genital warts dropped 71%. And then for vaccinated women, the percentage of cervical pre-cancers caused by these types, so HPV resulted in a drop of 40% in cervical cancer. So these are things that really are successful outcomes from, I mean, as we walk through, we started with the live attenuated.
Then we went to the next, which is the killing essentially of the virus and using that for the vaccine to the sub units, which are even more building in that engineering for much more robust response from the immune system. So Chris, did you know all of that? - I did not know all of that. So for the flu vaccine that we get every year, which one of those categories would that fall under? - So for the standard flu vaccine, it falls under the sub units typically. So those are the more recent flu vaccines.
- And can you explain to us the audience, why do we need a flu vaccine every year where some of the other, the MMR, the chicken pox, a lot of those vaccines are a one-time shot when you're a child? - So, the flu is a different type of virus, and there are different versions essentially of the flu that come out every single season. So again, when we talked about your immune responses, they are different. Because what'll happen is, is if you're exposed to one version of the flu, and then it essentially mutates, let's say you get the flu vaccine in October, and we have one strain of flu that comes out like influenza A, that was what the flu vaccine was generated to then, specifically, let's just say that specific example. Then what happens is, is that you probably will have about six months of protection.
And that's literally because the flu is changing over time. So every single year the companies and the manufacturers are trying to essentially predict what type of flu is going to be within the environment that they need to protect us from. So they're always trying to stay one step ahead. It's very much controlled by like the CDC and the World Health Organization where they have labs that are constantly looking at what strains of the flu are out there. And they use a lot of different mechanisms to do that.
I don't even know if everyone really understands that, but they do a lot of surveillance in animals. They also look at human data. And what they'll do then is, they usually come up with the flu vaccine for a period of a year.
But again, when we get the vaccine, sometimes even people go and get a vaccine in October, and then they'll go get a vaccine more in the springtime as well to just increase that protection against the flu strains that are out in that particular year. - But the vaccines that come from the different companies, they're all using the suggested strains for that flu season? - Yes. So an important distinction, Chris, is that we saw this with H1N1. So H1N1 was a strain of the flu that was extremely dangerous and caused a lot of adverse effects within individuals that were exposed to the flu.
So there are essentially differences in each flu strain every single year, some of which some physicians will say, oh, it's not really that bad of a flu season, because the flu that year, how it's mutated is just not as strong, and it does not cause as many infections as opposed to the year that we saw H1N1 or the swine flu. And it really transmitted between individuals quite rapidly. Individuals that were exposed to H1N1 got extremely ill, there were many hospitalizations, and they did see the pneumonia, the respiratory issues. So those types of years, and with the flu, it really is why we have to have a flu vaccine every year where they're trying to predict what strain we're gonna see to try to protect as many people as possible, especially the elderly population, similar to COVID. The elderly population is also impacted by the flu viruses.
And so it's really important that they get the flu vaccines each year, whether or not they get them just once a year or multiple times a year to protect them through the fall and summer months. Usually, those are the highest for the flu. And one of the things that is really interesting too is each of the barriers and hospitals keep track of that. So they keep track of every single case for the flu that comes in, whether or not they test them for the flu or not. Because they're trying to look at how many individuals within a community and it's down to the county level are exposed to the flu so that again, they can start tracking and getting samples that they can start to look at what type of flu is really prevalent that year.
- Dr. Satterwhite's breadth of knowledge about vaccine development is impressive. And her ability to explain the science in such a straightforward way is really a gift. With so much in the news currently about the work to develop a COVID vaccine, her overview underscores the importance of truly understanding of vaccines effectiveness and safety before recommending mass immunization. There's always been a fascination about the various approaches to vaccine development, but what truly amazes me are the new approaches to vaccines that work to prevent cancer. Chris took the opportunity to ask Tina more about that.
- And there's all these different variables with the flu vaccine, but how does that work? - So now that we talked about the flu and why we get the flu vaccine each year, there's also other ways that we utilize vaccines. And so we kind of just walked through traditional vaccines that are produced within eggs, or they're cell-based, or we even went into some of the recombinant vaccine production techniques. And so, all of these vaccines that we just talked about were truly for protection against viruses and bacterias that over history have been quite dangerous.
But we use them for that protection, but there are other uses for vaccines, Chris. - Can you tell us more about that? What are these other use cases? - So what I wanted to talk to you about were some of the cancer immunotherapies. And within cancer immunotherapy, one of the types of drugs that are engineered are vaccines, and really these vaccines are doing the same exact thing that we just talked about by stimulating your immune system. But now what we're trying to do is we're trying to stimulate the immune system not to fight a pathogen like a bacteria or a virus, but we're utilizing our immune systems to attack cancer. And so what happens with cancer is that, you have to remember a virus and a bacteria are non-self, we've talked about how the immune system sees everything that is part of your own body as itself. But it sees any kind of foreign invader like a bacteria and a virus essentially as a non-self.
So it'll see like a sugar sequence on the bacteria or a sequence in the virus that doesn't quite fit. However, if you think about cancer, where does cancer come from, Chris? - Our own bodies. - That's right. So, it comes from our own bodies. And because of that, then our immune system can have a hard time recognizing that sequence essentially as non-self.
Or what can happen is it initially recognizes it as non-self, but then cancer cells are extremely smart. They almost cloak themselves to our immune system. And so really these cancer immunotherapies, these have been really expanding over the last five to eight years. And a big part of that has been trying to look at vaccines, and can we use the same technology that we've used for this protection against various diseases that we're exposed to to actually fight cancer, which is a disease that really is our own self.
And there's a lot of reasons that individuals get cancer, but every single cancer cell is your own cell, it just transforms. And when that goes through that transformation and it replicates essentially out of control. And so that's where you get different types of cancers that are more like blood disorders, like lymphoma, or you have solid tumors that are the result of that one cell dividing incorrectly and then forming cancer. So again, what vaccines do in this area is that, if we talked about these antigens, what happens on a cancer cell is that you have proteins or sequences that are being expressed onto the cancer cell that again, you wouldn't see in a normal healthy individual. And so you can use those antigen sequences to essentially build a vaccine to that particular cancer. And then they're trying to utilize those vaccines to stimulate that immune system, uncloak the cancer cell, and get a really robust immune response from yourself.
And what they have to do to make that work is they have to be able to have the immune system see that cell as non-self. So again, I think in this area, the engineering is getting better and better every single year, but there really hasn't been a smoking gun that's come out in regards to vaccines that has truly shown a lot of its effectiveness, so efficacious. So we'll see in the next generation of these types of drugs whether or not we see more impact from them versus the other existing cancer immunotherapies that have been approved over the last 10 years.
- Tina, you mentioned that this is a pretty new technology that they're going with for cancer immunotherapies. Are there any cancers right now, specific cancers that have a vaccine or immunotherapy for them publicly available? - Yes, there is. Yeah, so there's one treatment that was approved in 2010 and it was for prostate cancer and it's called Provenge. That particular vaccine is pretty much one of the first ones that got approved by the FDA. - And I'm assuming the earlier the stage of cancer, the better these immunotherapies will work. - And the best thing would be to have more protective vaccines.
So if we can link viruses to more cancers, then I think we'll be in a much better place to actually protect as opposed to wait until you already have cancer, and then try to administer a vaccine that then has to be able to, like I said, uncloak those antigen, so your immune system sees them as non-self. And then there'll be more effective, but there's been a lot of different issues that these vaccines for cancer immunotherapy have had to overcome to get to that level of being more effective. So I think that there's some more engineering that needs to happen there. Hopefully, over the next several years, we'll see another approval of a vaccine in this area. - And speaking of vaccines that we want to see sooner than later is COVID. Let's talk more about what we have right now.
There's a lot of news surrounding the phase three clinical trials. What do we have out there for the foreseeable future? - So for the foreseeable future, I think that we are really in a state where we have a lot of drugs in the different phases of drug development. I think it was at the beginning of March, there was really a call to all of the biotech and pharmaceutical companies to really focus a lot of their effort to get a vaccine or a more novel vaccine to get approved as quickly as possible. So I think we've all heard about Operation Warp Speed. It was really pulling together all the pharmaceutical biotech companies, as well as manufacturing and support to really devise a plan that they could get these drugs to market as quickly as possible. So I just looked it up today, as of today, according to the World Health Organization, there's 34 million confirmed cases of COVID.
And as we move into the fall season, as you can see, like it's gonna be super important that we have hopefully a vaccine by the end of the year, because now we're gonna have potentially more issues because we're getting into the flu season. And then if we have like additional infections with COVID, it would be definitely ideal to have a vaccine that can fight that. So right now, in phase three, there were five current vaccines. And so if you kind of think about this from March till now, so it's October, to have five different types of vaccines in phase three clinical trials is actually tremendous.
I think that the individuals that have been working on these at the pharmaceutical and biotech companies have really been working extremely hard over the last several months to get these drugs as far as they have so far within the clinical drug development process. So for example, we hear a lot about Moderna. They have a novel mRNA vaccine that's in phase three as of July. And again, when we talked about the different types of vaccines and we talked about cancer immunotherapy, the mRNA vaccine that they have at that company is the next generation of vaccine, so that's really using DNA and RNA sequences, so very specific to generate vaccines. So we'll see how some of these vaccines go through.
Another example is Pfizer. They have an mRNA vaccine as well, and they're in phase two, three. So we'll see, they have high hopes that they'll actually conclude a lot of their clinical trials here by the end of October, and then be able to submit their data for the approval process. And then we have other vaccines that have come out that are really developed DNA technologies that use, again, different types of platforms.
So not just the mRNA, but DNA. And then we have more traditional vaccines as well, where they're looking at just subunit sequences to utilize the more traditional technology. But really, I think right now, when you look at you those five vaccines that are essentially in that phase three, there's a mix of these like newer technologies and then the older technologies for vaccines.
So one of the things that's important to note is that, sometimes when they're looking at drugs and how safe they are, if we're using the more traditional path of utilizing antigen sequences and then known adjuvants, and I don't think I really hit on what adjuvants are, but adjuvants are a part of the formulation of the vaccine that also is there to additionally stimulate or boost your immune system. So if you're using that same formulation that's been used previously, which is exactly what they do with the flu vaccine typically every year. They're using the same formulation, they're just changing sequences. So they already know that the formulation is safe, so if you just change the sequence, you should be able to go through that pretty quickly. That's another thing is some of these drugs, when they're looking at it and they're more traditional, they may be able to move through their approval process quicker.
I don't really know, 'cause we don't know what the packages are for some of the newer technologies and how they're being submitted or what data they have. But they might have just more questions by the FDA, because they are newer types of drugs as opposed to those traditional vaccines. And I think there's something like as of today, 46 current vaccines in clinical trials. And I think there's 96 in preclinical testing, to give you an idea.
That's a pretty sizeable number of potential new drugs for a virus that we only found out about in January. - And we learned from our last episode the traditional time it would take a vaccine is in that 10 to 15 year range. So this is quite a departure from that. - Correct, yep. But I mean, I think that, as we move through and everyone gets a chance to look at the data, the other big part of a phase three clinical trial is to make sure that the drug actually works and that it will protect. So that'll be a big part of the evaluation of the data.
- Tina, again, thanks so much for taking the time to explain immune mechanisms and for sharing your expertise with us at Vital Science. - Yeah, Chris, I really appreciate you having me come and talk about something that I'm extremely passionate about. I hope that you learned a little bit more about the immune system and about vaccines.
I know that every single day right now, I know it's a topic of conversation for me with my family, my friends, people in the community are very curious and want to make sure that they understand how viruses work, why is COVID so bad and why is it different. And so I think that really taking us through this history and how the immune system works will really make things a lot more clear for you. - And I think you did that today. Thank you so much for your time.
- Thank you for listening to this episode of Vital Science. You've heard Dr. Satterwhite talk about the incredible number of COVID vaccines currently in clinical trials. But what did it take to get them there? Join us next month for the third episode in our vaccine series, where we get down to the business of accelerating vaccine development. We'll hear from our own Dr. Lauren Black, a former FDA regulator and current scientific advisor who will share some insight into this process.
Have questions or comments about anything you heard today, reach out to us at firstname.lastname@example.org. Also be sure to check out our sister podcast, Sounds of Science, focusing on innovation and trends in the life science industry. I'm Gina Mullane. Thanks for listening.