S2, E02: A Formidable Defense Against Infectious Diseases


About this Episode

When the immune system is compromised, people rely on vaccines to eliminate and inactivate the threat. However, the process with which this happens is anything but simple. Dr. Christina Satterwhite joins us to explain how the immune system works and how vaccines target harmful pathogens in the second installment of our series on vaccines.

  • Episode Transcript

    Gina Mullane (00:06):
    Welcome back to Vital Science, and 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/vital science. You can also find us on Apple podcasts, Stitcher, Spotify, or anywhere you access your favorite podcasts.

    Gina Mullane (00:41):
    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.

    Gina Mullane (01:18):
    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.

    Chris Garcia (01:44):
    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?

    Dr. Christina Satterwhite (02:00):
    Yes, Chris. I would be happy to do that. Currently, we are talking about viruses in this country every single day. 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. 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 [inaudible 00:02:27], the different layers of the heart. Number one is the skin. The skin is your very first barrier to any kind of pathogen.

    Dr. Christina Satterwhite (02:35):
    Again, we're talking about viruses or bacteria. 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. Typically, historically, the way that it's described is you have a nonspecific or what we call the innate immune system, versus a specific or adaptive immune system.

    Dr. Christina Satterwhite (03:17):
    The immune system is really made up of a lot of different types of cells. What I'll do first is talk about our innate immune system. 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. 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.

    Dr. Christina Satterwhite (03:56):
    They tried 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. 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. 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.

    Dr. Christina Satterwhite (04:43):
    This portion of your immune system is made up of different cells. Typically, when you hear individuals talk about it, they're going to talk about your white blood cells. Your white blood cells are encompassed by lymphocytes. 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. When we talk about the difference between T cells and B cells, B cells are part of your humoral immunity.

    Dr. Christina Satterwhite (05:25):
    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. When you are exposed to, let's just say, a virus, what happens is that your B cells are activated. They go ahead and they generate IgM and IgG antibodies. Those antibodies allow you to essentially clear the virus. That response usually though for the B cells takes between 7 to 14 days.

    Dr. Christina Satterwhite (06:12):
    Really, the IgG response, which is your memory response, 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. What will happen is when that same virus is seen by our immune system, then the B cells will go in and clear those viruses. 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.

    Dr. Christina Satterwhite (06:54):
    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. Your T cell responses, essentially, also have a memory component. 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. They go ahead and they recognize that. Then they go and attack.

    Dr. Christina Satterwhite (07:39):
    You have actually two components of T cells. Well, there's actually more than two, but these are the main components of your T cells. You have helper T cells, which are CD for 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. Really, what they're finding out right now with COVID-19 is that their theory or the thought is that the immunity that individuals are acquiring after being exposed is more from T cells and B cells.

    Dr. Christina Satterwhite (08:22):
    There's quite a few papers that have come out recently about that. Again, it's really early days in trying to figure out exactly how that immune response to that particular virus is mounted. I just want to make sure I 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. As we move through and talk a little bit more, there's going to be some important terms that you need to understand.

    Dr. Christina Satterwhite (09:03):
    Which is, when we're talking about antigens, those antigens that our immune cells recognize as with the nonself. It's a sequence of proteins that we don't typically see or that we haven't seen before, to make that clear. Those are immune cells. Essentially, what they'll do is any kind of, if we're talking about a bacteria, it could be a sugar sequence and a bacteria that they're recognizing and saying, oh, I don't have that sugar sequence, and so I'm going to go and attack that.

    Dr. Christina Satterwhite (09:42):
    You can almost, when you think of the immune system within your body, constantly surveilling and ensuring that if there's any kind of 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 going to get. 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.

    Dr. Christina Satterwhite (10:26):
    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. With their memory, essentially, since they've seen that sequence once in your life, they can attack at any time after that. They will always recognize those sequences from what they were exposed to.

    Dr. Christina Satterwhite (11:13):
    Again, it's important to understand those concepts as we move forward through this discussion. 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. 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.

    Dr. Christina Satterwhite (11:53):
    You're exposed to bacteria, you're exposed to viruses daily. 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.

    Chris Garcia (12:13):
    Right. 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?

    Dr. Christina Satterwhite (12:32):
    Chris, I just wanted to walk you through what the different types are for different vaccines. We have what you call live attenuated vaccines, inactivated vaccines, toxoid vaccines, as well as subunit or conjugate vaccines. 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. 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.

    Dr. Christina Satterwhite (13:21):
    What they do is they weaken the virus or the bacteria. They do this through different means to essentially accomplish that goal. 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. For these types of vaccines, really, the only thing is a lot of them are sometimes manufactured or produced an egg. People that have egg allergies, these would not be very good. They could have an allergic response to them.

    Dr. Christina Satterwhite (14:03):
    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. 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. Really, for the live attenuated, there's really not that many disadvantages. Really, besides being producing eggs, they're extremely safe.

    Dr. Christina Satterwhite (14:48):
    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?

    Chris Garcia (15:08):
    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?

    Dr. Christina Satterwhite (15:23):
    Yeah. Essentially, what the attenuated live viruses are doing is they're weakening, essentially, that form that you're being given. 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. We go back to that discussion we just had about the immune system. What happens initially is you can get a fever. You can elicit other types of responses as well.

    Dr. Christina Satterwhite (16:08):
    If you get an intramuscular injection for the MMR, typically, what you'll feel is almost like a little bump. It's considered an induration. 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 the MMR, it's trying to attack that sequence that it sees again. The number one thing to remember about this is those effects are very transient. They typically occur within the first 24 hours.

    Dr. Christina Satterwhite (16:40):
    If you ever have any concerns, the number one thing your pediatrician would say, if it's child and adult too, they can take Tylenol or ibuprofen, so that it really dampens any of those responses that are seen. Again, you do want to get the best immune response you can. Again, I think, hopefully, that addressed your question. We can move on to inactivated viruses and bacteria. Some great examples of that would be polio. Polio, the vaccine, is probably been the most effective at completely eradicating a disease.

    Dr. Christina Satterwhite (17:20):
    Another member of this group is Hep A vaccines, as well as rabies. We all know, really, at this point for rabies, you bring your dogs in and they get their rabies vaccination. That's mainly to protect them if they're exposed to a bat or I think, mostly, it's bats that carry rabies. The difference between the live attenuated vaccines and the inactivated is that the virus essentially, let's say, it's a virus, you're growing it into cells. This is how you're essentially making it. Then you go ahead and you purify it from the cells.

    Dr. Christina Satterwhite (18:04):
    What you do is you just completely kill it through means of maybe it's a chemical mean or it's UV or something like that. You're going to go in and you're just going to completely kill the ability of that virus to cause you any harm. What it is, though, is it does maintain, again, those sequences. What they can do is they can take those inactivated viruses or bacteria and then they can essentially deliver that as a vaccine. You utilize that process instead of the attenuated live vaccine. Then your immune system, again, will mount a response to those sequences.

    Dr. Christina Satterwhite (18:52):
    You'll build up that protection. That's really the difference between the inactivated and the live attenuated. Then what we have is the toxoid type vaccines. This would be such as diphtheria and tetanus. This is another vaccine that we all get when we're younger. It's part of the vaccinations that you have to have, essentially, to go to school. 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.

    Dr. Christina Satterwhite (19:34):
    The difference here in this type of vaccine is they take the antigens from the toxin and then they can chemically inactivate it. It's the same as I was just describing, except for, instead of a virus or bacteria, the source is components of a toxin. Those are chemicals. It's a little bit different because it's not derived from a protein. Then the last is you have the subunit. This is the category where you would have like pertussis, Hep B, and HPV. Subunit vaccines include only the components or antigens that best stimulate the immune system.

    Dr. Christina Satterwhite (20:23):
    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. There's all these different components of that particular virus. Your immune system responds differently to those components. 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.

    Dr. Christina Satterwhite (21:07):
    They'll look at T cell immunity as well as B cell immunity. They're going to make and they're going to engineer that particular vaccine to the sequence that has the strongest response. An example of that was whooping cough. Where they after the '70s, they went ahead and they developed a more advanced generation of that vaccine. That was really the purified pertussis components. They saw a lot less side effects. When you talk about safety, Chris, this is an example of that.

    Dr. Christina Satterwhite (21:47):
    They had previous versions of the pertussis vaccine, but people would have fever or a lot more swelling at injection sites. By changing to the 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. 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?

    Chris Garcia (22:27):
    No, I haven't.

    Dr. Christina Satterwhite (22:28):
    Okay. Gardasil is a vaccine that was made against HPV, so that's human papilloma virus. If you're not aware the human papilloma virus, once you're exposed to it at a younger age, can result in certain types of cancers. 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.

    Dr. Christina Satterwhite (23:19):
    Gardasil is essentially a vaccine that really revolutionized women's health, if you think about that, and even men's health. Because sometimes what happens is, if you were exposed to HPV as a young adult, and 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.

    Dr. Christina Satterwhite (24:05):
    What happens with Gardasil is it works to stimulate the immune system to attack four different types of HPV, 6, 11, 16, and 18. Once it's administered, it's viral proteins, because again, it's the subunit type of vaccine. It's made up of all the specific subunits of those four types that have been shown to get the best immune response. Essentially, so far, it's really been effective. Amongst teen girls, infections with HPV types that can cause HPV cancers and genital warts has dropped 86%.

    Dr. Christina Satterwhite (24:45):
    Among adult women, infection with HPV types that cause most HPV cancers and genital warts dropped 71%. 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. 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 subunits, which are even more building in that, engineering for much more robust response from the immune system. Chris, did you know all of that?

    Chris Garcia (25:43):
    I did not know all of that. For the flu vaccine that we get every year, which one of those categories would that fall under?

    Dr. Christina Satterwhite (25:51):
    For the standard flu vaccine, it falls under the subunits, typically. Those are the more recent flu vaccines.

    Chris Garcia (26:03):
    Okay. Can you explain to us, the audience, why do we need a flu vaccine every year where some of the MMR, the chicken pox, a lot of those vaccines are a onetime shot when you're a child?

    Dr. Christina Satterwhite (26:19):
    Right. The flu is a different type of virus. There are different versions, essentially, of the flu that come out every single season. Again, when we talked about your immune responses, they are different. Because what will happen 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.

    Dr. Christina Satterwhite (26:59):
    Then what happens is, is that you probably will have about six months of protection. That's literally because the flu is changing over time. Every single year that 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. They're always trying to stay one step ahead. Usually, it's very much controlled by the CDC and the World Health Organization, where they have labs that are constantly looking at what strains of the flu are out there.

    Dr. Christina Satterwhite (27:40):
    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. What they'll do then is they usually come up with the flu vaccine for a period of a year. 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.

    Chris Garcia (28:18):
    The vaccines that come from the different companies, they're all using the suggested strains for that flu season?

    Dr. Christina Satterwhite (28:25):
    Yes. Okay. An important distinction, Chris, is that, and we saw this with H1N1. 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. 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.

    Dr. Christina Satterwhite (29:16):
    It really transmitted between individuals quite rapidly, individuals that were exposed to H1N1 got extremely ill. There are many hospitalizations. They did see those, the pneumonia, the respiratory issues. Those types of years 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 going to 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.

    Dr. Christina Satterwhite (29:59):
    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. One of the things that is really interesting too, is each of the areas in hospitals keep track of that. 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.

    Gina Mullane (30:46):
    Dr. Satterwhite's breadth of knowledge about vaccine development is impressive. Her ability to explain the science in such a straightforward way is really a gift. 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. 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.

    Chris Garcia (31:24):
    There's all these different variables with the flu vaccine. How does that work?

    Dr. Christina Satterwhite (31:30):
    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. We just walked through traditional vaccines that they are produced within eggs or they're cell based or we even went into some of the recombinant vaccine production techniques. All of these vaccines that we just talked about were truly for protection against viruses and bacterias that over history, had been quite dangerous. We use them for that protection. There are other uses for vaccines, Chris.

    Chris Garcia (32:21):
    Can you tell us more about that? What are these other use cases?

    Dr. Christina Satterwhite (32:26):
    What I wanted to talk to you about were some of the cancer immunotherapies. Within cancer immunotherapy, one of the types of drugs that are engineered are vaccines. Really, these vaccines are doing the same exact thing that we just talked about by stimulating your immune system. 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. What happens with cancer is that, you have to remember, a virus and a bacteria are nonself.

    Dr. Christina Satterwhite (33:13):
    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 nonself. 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?

    Chris Garcia (33:44):
    Our own bodies.

    Dr. Christina Satterwhite (33:45):
    That's right. It comes from our own bodies. Because of that, then our immune system can have a hard time recognizing that sequence essentially as nonself. Or what can happen is it initially recognizes it as nonself, but then cancer cells are extremely smart. They almost cloak themselves to our immune system. Really, these cancer immunotherapies, these have been really expanding over the last five to eight years. 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.

    Dr. Christina Satterwhite (34:49):
    There's a lot of reasons that individuals get cancer, but every single cancer cell is your own cell. It just transforms. When that goes through that transformation, it replicates. It replicates essentially out of control. 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. 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 on to the cancer cell that, again, you wouldn't see in a normal healthy individual.

    Dr. Christina Satterwhite (35:46):
    You can use those antigen sequences to essentially build a vaccine to that particular cancer. 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. What they have to do to make that work is they have to be able to have the immune system see that cell as nonself. Again, I think in this area, the engineering is getting better and better every single year.

    Dr. Christina Satterwhite (36:24):
    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. 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.

    Chris Garcia (36:57):
    You mentioned that some of 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 ...

    Dr. Christina Satterwhite (37:10):
    Yes, there is.

    Chris Garcia (37:11):
    ... probably available?

    Dr. Christina Satterwhite (37:14):
    Yeah. There's one treatment that was approved in 2010. It was for prostate cancer. It's called Provenge. That particular vaccine is pretty much one of the first ones that got approved by the FDA.

    Chris Garcia (37:33):
    I'm assuming the earlier the stage of cancer, the better these immunotherapies will work.

    Dr. Christina Satterwhite (37:40):
    Right. The best thing would be to have more protective vaccines. 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 antigens, so your immune system sees them as nonself. Then they'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. 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.

    Chris Garcia (38:31):
    Okay. 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?

    Dr. Christina Satterwhite (38:49):
    Yeah. 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. 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.

    Dr. Christina Satterwhite (39:41):
    I just looked it up today, as of today, according to the World Health Organization, there was 34 million confirmed cases of COVID. As we move into the fall season, as you can see, it's going to be super important that we have hopefully a vaccine by the end of the year. Because now we're going to have potentially more issues, because we're getting into the flu season. Then if we have additional infections with COVID, it would be definitely ideal to have a vaccine that can fight that. Right now, in phase three, there were five current vaccines.

    Dr. Christina Satterwhite (40:27):
    If you 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 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. For example, we hear a lot about Moderna. They have a novel mRNA vaccine that's in phase three as of July.

    Dr. Christina Satterwhite (41:10):
    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. That's really using DNA and RNA sequences, very specific to generate vaccines. We'll see how some of these vaccines go through. Another example is Pfizer. They have an mRNA vaccine as well. They're in phase two, three. 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.

    Dr. Christina Satterwhite (42:05):
    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. Then we have more traditional vaccines as well, where they're looking at just subunit sequences to utilize the more traditional technology. Really, I think right now, when you look at those five vaccines that are essentially in that phase three, there's a mix of these newer technologies and then the older technologies for vaccines.

    Dr. Christina Satterwhite (42:50):
    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. 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.

    Dr. Christina Satterwhite (43:30):
    They're just changing sequences. They already know that the formulation is safe. 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 the approval process quicker. I don't really know, because 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.

    Dr. Christina Satterwhite (43:58):
    They might have just more questions by the FDA, because they are newer types of drugs as opposed to those traditional vaccines. I think there's something, as of today, 46 current vaccines and clinical trials. I think there's 96 in preclinical testing, to give you an idea. That's a pretty sizable number of potential new drugs for a virus that we only found out about in January.

    Chris Garcia (44:30):
    Yeah, we learned from our last episode the traditional time it would take a vaccine, is in that 10 to 15-year range. This is quite the departure from that.

    Dr. Christina Satterwhite (44:41):
    Correct, yeah. 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. That'll be a big part of the evaluation of the data.

    Chris Garcia (45:01):
    Tina, again, thanks so much for taking the time to explain immune mechanisms and for sharing your expertise with us at Vital Science.

    Dr. Christina Satterwhite (45:08):
    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, very curious and want to make sure that they understand how viruses work, why is COVID so bad, and why is it different. 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.

    Chris Garcia (45:55):
    I think you did that today. Thank you so much for your time.

    Dr. Christina Satterwhite (45:57):

    Gina Mullane (46:00):
    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. 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 adviser who will share some insight into this process. Have questions or comments about anything you heard today? Reach out to us at [email protected] 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.


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Hosted by: Chris Garcia
Narrated by: Gina Mullane

Special thanks to: Dr. Christina Satterwhite

Contact Vital Science™ at: [email protected]
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Check out our sister podcast Eureka’s Sounds of Science.