transcript

Speaker 1:
[00:00] This is Sleepy History. Sleepy History is a production of Slumber Studios. To listen ad-free, get access to bonus episodes, and support the ongoing production of this show, check out our Premium feed.

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Speaker 6:
[01:43] From the moment vaccination was discovered, it completely transformed human health and our experience of the world. In fact, modern human health is so different that it can be hard for us to conceive of what life was like before vaccines. Tonight, we'll try to put these massive changes into a historical context. We'll also learn about some of the people, procedures and science behind the vaccines that have saved hundreds of millions of lives since the 18th century. So just relax and let your mind drift as we explore the sleepy history of vaccines. Let's begin this history by talking a bit about the amazing success of vaccination. For nearly all of human history, infectious disease was the leading cause of death. Along with sanitation, vaccination is the safest and most effective tool humans have ever invented for preventing infectious disease. This is in large part because vaccination works alongside your natural immune system. It's a partnership between your body and medical science. We'll talk about how vaccines work a little later. Perhaps the greatest success vaccination has ever had is the eradication of smallpox. To date, this is the only disease that has ever been completely eradicated in humans. The last known naturally occurring case of smallpox was in 1978, after a 20-year vaccination campaign by the World Health Organization. It hasn't been seen since. It's hard to overstate the magnitude of this achievement. Depending on the type of smallpox a person was infected with, the mortality rate could be anywhere between 1% and 90%. This rate tended to be much higher for children. For people who survived infection, there was still a high risk of complications, such as scarring, brain inflammation and blindness. Smallpox wasn't some rare disease either. Quite the opposite. In the early 1950s, smallpox infected 50 million people each and every year. And then, just 20 years later, it was gone. This disease, which had once affected every nation on earth, which had been infecting humans for tens of thousands of years, which had left millions of people heartbroken, was eradicated for good. How did we manage it? The story of smallpox vaccination and vaccination in general begins in 16th century China, with a different procedure known as variolation. Some say this practice began even earlier, perhaps as early as the 11th century. In this era of human history, smallpox was one of the biggest threats to human life. People were desperate for some kind of cure or prevention. While many of these early treatments didn't work, one seemed to be effective. Variolation. Variolation was a rudimentary way for early physicians to protect patients from smallpox. These early physicians had noticed a basic truth of smallpox. Patients who survived infection rarely became reinfected with the disease. Variolation was the practice of intentionally infecting people with weakened smallpox in order to protect them from a worse case. Physicians would seek out people who were sick with mild cases of smallpox. The milder the better. They would then transfer the infection from the sick person to a healthy person. Weakening the disease further in the process. If successful, variolation would produce long-lasting immunity to smallpox at the cost of a very minor infection. These inoculations were effective enough that they became popular among wealthy and well-connected people. The third emperor of the Qing dynasty had both his children and his regular troops receive variolation treatment. Centuries later, the procedure made its way to Europe, where Catherine the Great and her court would also receive it. But variolation was very risky. Around 1-2% of people who were variolated died from the intentional smallpox infection. Smallpox in this era had a mortality rate of around 30%, so this was still a much lower risk than a natural infection. The 1-2% mortality rate is why variolation wasn't used for everyone at all times. It was widely used under circumstances where a more dangerous smallpox infection was likely, such as in the middle of an outbreak. We remember variolation now because it was the natural precursor to vaccination. Physicians in the 18th century were familiar with variolation, but they didn't know how it worked. Germ theory had not yet been invented, and nobody knew what actually caused the diseases they were trying to treat. But they knew that variolation worked most of the time. So they set out to modify the procedure in search of a way to make it safer and possibly more effective. There were a number of people investigating this problem, including John Fuster, Peter Plett and Benjamin Jesty. The one best remembered today is Edward Jenner, the first person to give what we would call a true vaccination. In 1768, John Fuster made a crucial observation. Prior infection with cow pox seemed to make a person immune to smallpox. Cow pox is an infectious disease that mainly infects cows, but occasionally jumps to humans, especially farmers and milkmates who spend a lot of time around cows. It's not a fun disease to have, but it's nowhere near as serious as smallpox. At a meeting, Fuster suggested that members of his medical society should investigate this interesting connection. One of the people at this society meeting was a young Edward Jenner. Jenner went on to conduct several experiments that were effective, but are now widely considered unethical. He vaccinated several people with cowpox, and then intentionally exposed them to smallpox. A very dangerous thing to do if he was wrong. His findings were published in a paper in 1798. It concluded that the cowpox inoculation was a safer alternative to variolation. This was the first successful attempt at vaccination. Smallpox may be long gone, but Jenner's early vaccine is immortalized in the very word we now use. Vaccine is derived from the Latin adjective vaccinus, which means from the cow. Following Jenner's vaccine trial, the smallpox vaccine was rapidly distributed around the world, and Jenner's work was translated into all major European languages. In 1804, the Balmis expedition sailed around North and South America, with the explicit goal of delivering the smallpox vaccine throughout the Spanish Empire. Napoleon gave all his military recruits the vaccine. It only took until 1806 for the Swiss state of Turgau to introduce mandatory smallpox vaccination. What Jenner couldn't have known was how the vaccine, smallpox or cowpox worked. He just saw that it did and made the most of it. We now know that cowpox and smallpox are closely related viruses, and that this is the key reason why his vaccine was effective. Now is a good time to talk about the science behind vaccines. It's easier than you might think to understand, and the smallpox vaccine is a great entry point. To start with, you can't understand why vaccines work without understanding some basic facts about the human immune system. Our immune systems exist to protect us from disease. We have two different types of immune systems, the innate immune system and the adaptive immune system. The innate immune system is important, but it's not our focus tonight. All you need to know is that it responds quickly, isn't very good at identifying specific threats, and doesn't have much of a memory. The adaptive immune system, on the other hand, is all about responding to specific viruses, bacteria and other pathogens. It takes some time to mount a response, though, which is why a cold, for example, will last a few days before you start getting better. When you catch a cold, your innate immune system responds first, and encourages more immune cells to come to the site of infection. Most of the cold virus will escape into your body, but some of the individual viruses will be captured and devoured by some of your innate immune cells. Then the adaptive system shows up. It handles specific threats, and wants to know exactly what's attacking your body. The innate immune cells that devoured cold viruses will go through a process of antigen presentation. Essentially, they tear the cold virus into little tiny pieces and present those pieces to the adaptive system. The adaptive system then looks for a specialist. On the cellular level, your body is a very big place. Adaptive immune cells, also known as T cells and B cells, are constantly circulating in your lymphatic system, waiting for a chance to help out. Imagine a firefighter who specializes in fires at mineshafts. They may never be asked to use that specialty, but if there's ever a mineshaft fire, you know who to call. In a similar way, you have millions of T and B cells, and each of them are uniquely equipped to recognize and deal with a specific kind of intruder. Your T cells encounter the torn-up pieces of the cold virus that are presented to them. None of them have any reaction. The cold virus isn't their specialty. But then one T cell reacts. It recognizes the piece. Now it can get to work. It divides itself rapidly into an army of identical copies. These copies are all capable of recognizing the cold virus, and they work together to clear the infection. B cells are different. They don't need the cold virus to be torn up into pieces and presented to them. Instead, they encounter the virus or pieces of the virus as they circulate in the bloodstream. When a B cell recognizes its matching piece, it divides rapidly into an army of B cells that are capable of producing antibodies that bind to the virus. In this way, T cells and B cells work together to clear infections, but what's really important is what happens afterwards. Some of them become long-lived memory cells. These memory cells continue to circulate through your body and retain the knowledge of how to fight that particular infection. If you were to catch the same cold again, your memory cells would respond and clear the infection immediately, while you experience basically no symptoms. All vaccines work on some version of this basic principle. If an inoculation can cause a T and B cell response from the immune system, you'll create memory cells that will protect the body in the future. Jenner didn't know that cowpox and smallpox were very closely related, so closely related that the memory cells produced after a cowpox infection were also effective at recognizing and stopping smallpox. But even then, Jenner's cowpox vaccine was still risky. Cowpox is much milder than smallpox, but it can still harm people because it is a live virus that hasn't been altered in any way. Also, Jenner hadn't considered the importance of creating the vaccine in a sterile environment. Today, live virus vaccines are very rare, and almost no current vaccines use a live virus to stimulate the immune system. In fact, in the early 1900s, a second generation of the smallpox vaccine was created. This one using a more sterile environment. In the mid 1900s, a third generation was developed. This time by taking the original cowpox strain and slowly selecting for weaker and weaker mutations over the course of many years. Eventually, researchers created a version of cowpox that couldn't even replicate inside the human body. This weakened cowpox vaccine had very few side effects, but still created lasting memory cells. This process of weakening is called attenuation. Attenuated vaccines or live attenuated vaccines are a category of vaccine that contain living pathogens that have had their severity greatly reduced. While smallpox was being eradicated from the 50s to the late 70s, two other dangerous infections were targeted for vaccination development by scientists. Polio and Measles Polio and measles were extremely dangerous diseases that harmed millions of children all around the world. Unlike with smallpox, there was no cow polio or cow measles that could be used as a vaccine. Other methods would have to be discovered. Enter doctors Jonas Salk and Albert Sabin. Salk and Sabin separately spent years researching an effective polio vaccine. They developed two different types at around the same time. Sabin, whose vaccine was released second, preferred an oral form, one that you could swallow like a pill. It was easy to take and didn't require any booster shots to ensure immunity. But his oral vaccine had a higher risk of side effects, because it used an attenuated virus. This was a problem, because in very rare cases, the virus in the vaccine could end up causing a polio infection. Salk, who released the first polio vaccine, saw those risks and preferred to remove them entirely. He created a vaccine made from killed polio viruses instead. Since the virus was completely dead, it was unable to do any harm to the body. The only problem was that his vaccine required one injection and two booster shots in order to be completely effective. This required people to remember to come in multiple times for injections, which also meant that doctors needed a lot of sterile needles. So, both Sabins and Salks vaccines could be considered more useful, depending on where they were being distributed and to what population. People who could return for boosters or not, for example. Salks vaccine belonged to a category known as either an inactivated vaccine or a killed vaccine. Inactivated vaccines had been developed before to fight cholera, plague and typhoid in the late 1800s. Both Sabins and Salks vaccines were used to vastly reduce the number of polio cases throughout the world. And neither scientist patented their vaccine, choosing to share their discovery freely, which helped it be distributed quickly, globally and affordably. Sabin once said he hoped the vaccine would be a gift to all the world's children, and noted that 2000 cases of paralytic polio in the United States, if they can be prevented, are 2000 cases too many. Again, it's hard to emphasize just how dramatic these changes were, at a time when infectious disease was a leading cause of death. In the United States, a polio outbreak in 1952 resulted in 58,000 cases, with thousands of deaths, and even more left with severe lifelong conditions. By 1957, after Salk's vaccine had been in use for only two years, there were only 5,600 cases. By 1961, the entire United States recorded only 161 cases of polio. In just nine years, polio cases were effectively zero. A similar thing happened with the measles vaccine. Measles was even more prevalent than polio and caused even more deaths in the United States. On average, in the 1950s, the country reported between 3 and 4 million cases of measles. Two vaccines were created in 1963, and, much like with polio, one was an inactivated virus and the other was an attenuated virus. Again, the results were dramatic. A vaccination campaign in the United States turned 3 million cases per year into just thousands per year by the 1980s. Between 1997 and 2013, no single year had more than 220 cases reported. It's worth taking a moment here to talk about an interesting vaccine that works a little differently from the others, the rabies vaccine. Ordinarily, vaccines must be given before a person is exposed to illness. Ideally, your body has a few days, if not weeks, to run the vaccine through your adaptive immune system and produce memory immune cells. Vaccines are preventative medicine. But, as you probably know, the first thing you're supposed to do following a wild animal bite is go get a rabies vaccine. Why is that? Isn't it already too late? Rabies isn't like many of the other diseases we vaccinate against. Specifically, it has a latency period, or delay, where the infected person doesn't show symptoms. This latency period can be as long as six years, in some cases, or as short as four days. It depends on the location and severity of the bite, along with how much virus is introduced to the system. This latency period is incredibly important. It gives time for the rabies vaccine to do its work, while the virus is essentially laying low and moving very slowly. Then, when the virus exits latency and attempts to fully infect your body, your immune system is ready for it. Before the vaccine, rabies was one of the few diseases that had a 100% mortality rate. Even today, a person who gets rabies but doesn't get a rabies shot will die from the disease. To put it another way, every single person who has ever survived rabies has survived it thanks to the rabies vaccination. It's also worth mentioning that the rabies vaccine was originally invented by Louis Pasteur and his assistant Emile Roux in the late 1800s. Pasteur is better known for creating the food sanitization technique that bears his name, pasteurization. But in the 1800s, he was one of the foremost creators of vaccines. He also successfully produced vaccines for use in farm animals, focusing on chicken cholera and anthrax in cows. During this time, Emile Roux was also interested in childhood diseases. In 1888, he successfully isolated the toxin that causes diphtheria, which was a major achievement. Diphtheria was commonly known as the strangling angel, given that it could cause fatal suffocation. Simultaneously, two other scientists at the University of Berlin were doing their own investigation of diphtheria and tetanus. These scientists were Kitasato Shibasaburo and Emile von Behring. Both research teams were looking for a diphtheria vaccine. Roux was in France, and Shibasaburo and Behring were in Germany. The research of both teams became a major story in Europe. It was a national rivalry. Everyone wondered who would reach the answer first and create a functional treatment for diphtheria. As luck would have it, both teams developed their diphtheria treatments at almost the exact same time. How did that happen? While many people treated the race for a diphtheria cure as a competition, Roux, Shibasaburo and Behring did not. They regularly adopted each other's experimental techniques and actively built off each other's research. It was more of a collaboration than a competition. In 1894, the first diphtheria treatment became available. But it was not a vaccine. It was something called serum therapy. Serum therapy is its own special and strange thing. The primary difference is that serum therapy is used after someone is already sick, while vaccines are taken before as a form of preventative medicine. However, serum therapy still uses the immune system, but in a very different way. To do serum therapy, a pathogen must be injected into another animal. As the animal's immune system fights off the disease, it produces antibodies. These antibodies can be isolated from the animal's blood in something called serum. If a person becomes sick with that disease, this antibody serum can be injected into their body to help fight the infection. But why horses? Because horses are really big and produce a lot of serum. Shibasaburo and a man named Paul Erlich, who was working on serum therapy, actually started with guinea pigs, but found they were too small. Today, serum therapy is not used as much, but its influence has echoed into a major part of modern medicine. You may have heard of monoclonal antibodies, which have been used to treat everything from COVID to psoriasis to certain types of cancer. Well, monoclonal antibodies are partially derived from the same research that produced serum therapy. So why are we talking about serum therapy in a history of vaccines? Because of what happened after Roux, Ehrlich, von Behring and Shiba Samburu developed the serum therapy for diphtheria, the discovery of the first toxoid vaccine. To understand what a toxoid vaccine is, we have to understand how different bacteria impact the body in different ways. Diphtheria is a disease caused by a specific toxin produced by a specific bacterial infection. This toxin is what causes the dangerous effects of the disease. Tetanus works in a similar way, with a different bacterial infection producing and releasing a different toxin into the body. What makes bacterial toxins challenging is that you can't really inject them as a vaccine. If you do that, you're just injecting someone with a dangerous toxin. There needs to be a way to make the toxin safe before vaccination. 30 years after serum therapy was discovered, Gaston Rameau began researching bacterial toxins while working at the Pasteur Institute in Paris. Rameau discovered that the diphtheria toxin could be inactivated through the use of chemicals, thus creating a form of the toxin that could be used in a vaccine without causing illness. This diphtheria vaccine was an immediate success, dropping the number of diphtheria cases in the United States from 200,000 in the 1920s down to 19,000 in 1945. From 1996 to 2018, there were only 14 cases reported in the country. Not 14 per year, 14 in total. Yet another deadly childhood illness that has functionally disappeared. Before we move on, we will touch on how in 1925, diphtheria serum therapy was at the center of a thrilling story. The Serum Run. In Nome, Alaska, a coastal town just two degrees south of the Arctic Circle, a diphtheria outbreak suddenly sprang up in the winter of 1924. Especially in such a remote community, an outbreak of any major disease can have devastating consequences. The only doctor in Nome discovered that all of the hospital's diphtheria serum was expired. He put out a call for help, but it was too late. The port was closed by ice for the winter, and there was no other way to bring the serum into Nome. The doctor and the mayor sent out radio telegrams asking for help, but they weren't hopeful. There was no way anyone could reach them, or so they thought. But against all odds, one group of intrepid people answered the call. Dog mushers. Dog sled teams ran a relay across 674 miles, or 1,085 kilometers, crossing the frozen tundra with the diphtheria serum tucked into their packs, as temperatures plummeted below negative 50 degrees Fahrenheit or negative 46 degrees Celsius. Twenty different teams passed the serum to one another over five days as they split up the run into multiple legs to complete it as quickly as possible, despite the harsh conditions. Eventually, the relay was successful with Norwegian musher Gunnar Carsten and his lead dog Balto traversing intense storms and poor visibility to finish the final leg of the relay and arrive in Nome. Not a single vial was broken and the serum was thawed within eight hours, ready to be used. The serum run is still honored today with the annual Iditarod Sled Dog Race, which follows a similar route across the far north to Nome. This just goes to show that vaccine history can be dramatic and exciting. It isn't all about people in lab coats looking into microscopes. As time went on, technological advancements allowed scientists to create vaccines that were more complex and more effective. Vaccines of the 1800s and early 1900s often used full viruses in either alive, attenuated or inactivated form because these were the only options available with the technology they had. In the 1980s, the first subunit vaccine was put on the market, the Hepatitis B vaccine. A subunit vaccine is a vaccine that only uses the parts of a pathogen that the immune system will react to. This has several important advantages over the older types of vaccine. Firstly, a subunit vaccine doesn't contain any live pathogens, so it has a 0% chance of causing infection. Secondly, the vaccine is more stable and can be kept in storage for longer. The disadvantages are important to note as well. These subunit vaccines are harder to manufacture and sometimes require booster shots. They may also require adjuvants to be included in the vaccine. Let's talk about adjuvants for a moment. An adjuvant is a substance that is added to a vaccine to intentionally activate the immune system. Why is this important? Because not all vaccines will naturally result in an adaptive immune response. Without that response, you can't develop immunity. Generally, your body is very good at deciding what does and doesn't require an adaptive immune response. If you fall down and skin your knee, your immune system will rally to heal the cut. This is mostly a good thing. You don't want your body overreacting to every little thing. But the whole point of a vaccine is to get a reaction. Some subunit vaccines, for example, could be ignored by your adaptive system. It makes sense. After all, the subunits aren't dangerous by themselves. That's where adjuvants come in. Adjuvants are selected based on their ability to stimulate an immune response across a wide range of people. There are dozens of different adjuvants made from many different things, including common oils, plant products and proteins from killed bacteria. The one common element is that these substances are not actually dangerous. They just look like a threat to your immune system, and that encourages your immune system to respond. With that knowledge, let's return to subunit vaccines. The hepatitis B vaccine took a long time to produce, with the work truly taking off in 1963, and Dr. Baruch Blumberg identified a key subunit in a blood sample from a person infected with hepatitis B. By 1976, Blumberg had won the Nobel Prize for his work on hepatitis B, and his eventual discovery of a new way to make a vaccine. He took blood samples from people infected with the disease, and then purified them to destroy all living viruses and bacteria, leaving behind only the key hepatitis B subunit. This could then be used as a vaccine. This blood-derived version of the vaccine was eventually taken off the market, and replaced in 1986. This new version of the vaccine was another leap forward for vaccination. It was the first human vaccine made using recombinant DNA methods. That's quite a mouthful. Recombinant DNA methods. So what does it mean? It's actually surprisingly simple. Hepatitis B is a virus made from DNA. This DNA is the blueprint for the virus' proteins. Proteins that include the key subunit that Dr. Bloomberg identified back in 1963. Researchers were able to take the specific section of DNA that codes for the key subunit and place it inside a different organism, yeast. Yeast is very easy to grow in a lab. So by putting a small section of hepatitis B DNA inside yeast, scientists were able to produce and isolate large amounts of the key subunit very quickly. This became the new way to produce the hepatitis B vaccine. Now let's jump forward even further and look at some of the modern vaccines that have changed human health forever. Earlier, we learned about how disease before vaccines was very different. Infectious illnesses were not just more common in human populations, they were also thousands of times more deadly. Making it through childhood without contracting a dangerous disease was an accomplishment. In the 1850s in England, just about half of all deaths were from infectious disease. In 1939, that number had plummeted to 14.5 percent. In 2012, it sat at just 6 percent. Following an explosion of new, life-saving vaccines in the mid to late 1900s, infectious disease was on the ropes. In addition to measles and polio, scientists had created effective vaccines against diphtheria, mumps, rubella, and many more. But there was still work to be done. Specifically, scientists were now learning more about the role that infectious disease plays in other severe conditions. Some seemingly low-risk diseases are capable of causing dangerous outcomes. There is no better example than the human papillomavirus or HPV. HPV infection is minor in the short term. In many cases, it has no symptoms. And even when it does have symptoms, they tend to be very mild. However, HPV infections also cause most cases of cervical cancer, with some estimates putting the rate at 90% or higher. It's not only cervical cancer either. A small collection of HPV strains are responsible for the majority of several other types of cancers as well. While these cancers are generally less common, it's still surprising to know that such an unassuming virus can do so much damage. Scientists from all over the world collaborated on finding, creating and distributing an effective subunit vaccine against HPV. A goal they accomplished in 2006. This vaccine has shown near 100% protection against the development of cervical pre-cancer. What does this mean in the real world? It means that this particular vaccine is also a vaccine against cancer. Studies have shown that widespread use of the HPV vaccine can effectively end cervical cancer and drastically reduce the rates of other cancers. A Scottish study from 2024 looked at nearly 450,000 health records from women in the country. They found 239 cases of cervical cancer, but none of these cases were in women who had received an HPV vaccine at 12 or 13 years of age.

Speaker 1:
[48:13] Zero.

Speaker 6:
[48:15] This means that the HPV vaccine, when given at the right time, could be considered a preventative for cancer. This is just one way that vaccines are moving from preventing dangerous infectious diseases to helping doctors prevent other life-threatening conditions. It should be noted that some diseases are more complicated than others. Different viruses have different methods of replication and different ways of causing symptoms. Some viruses mutate much more rapidly than others. These mutations can make the virus unrecognizable to your memory immune cells, even if you've been vaccinated. It's a tricky problem. It takes a long time to produce a vaccine that's effective against one strain of a virus. How can we protect against a virus that changes rapidly? This is the question that the entire world faced when the COVID-19 pandemic hit in late 2019. The answer was to find a completely new way to create vaccines. The result was the mRNA vaccine, perhaps the most flexible and advanced form of preventative medicine we've ever seen. To understand it, we need to learn a little bit about the relationship between DNA, RNA and proteins. DNA is the blueprint for all the proteins that make up your body. Without DNA, your cells would have no way of knowing what to do. But your cells don't just read your DNA at random, that would be really inefficient. Instead, there are special enzymes and proteins in your cells that help direct the protein making machinery to produce specific proteins in response to different situations. They do this by creating mRNA or messenger RNA. Messenger RNA is essentially a copy of a section of DNA that can be read by the protein making machinery in your cell. Imagine you have a 400 page cookbook and a team of 50 chefs. If you wanted them to make a specific cake recipe 200 times, you wouldn't silently hand them a single entire cookbook. For one, they'd have to flip through pages and pages of recipes and guess which one you wanted. Also, they'd have to share the book among themselves. The most effective way of getting your 200 cakes is to make 50 copies of the cake recipe you want and hand out one copy to each chef. Replace the cake with a specific protein and that's basically how mRNA works. So what is an mRNA vaccine? An mRNA vaccine involves creating mRNA strands that correspond to non-human proteins that would normally be produced by a pathogen such as a virus. Once a strand of mRNA is produced, it can be injected into the human body where our cells will absorb the mRNA strand. Once inside the cell, the protein-making machinery will use the mRNA to begin making hundreds of these proteins. After a while, the mRNA naturally breaks down and dissolves. Once these proteins exit the cell, the immune system responds and attacks the proteins, producing memory cells that protect against the pathogen. Why is this so effective? Because in a modern laboratory, mRNA is very easy to create, very easy to design, and very inexpensive to produce. Additionally, mRNA has none of the risks associated with live or attenuated vaccines, since it does not contain a living pathogen. When it comes to diseases like COVID-19, the biggest hurdle to eradicating the disease with vaccination is that the virus mutates rapidly. Each major mutation makes the previous vaccination dose a little less effective, although it's worth noting that studies have shown that any COVID vaccination can help prevent hospitalization, even if you get infected by a different strain. mRNA vaccines allow researchers to rapidly produce vaccines for new strains as soon as they can be identified. Once a new strain is identified in the population, researchers can sequence the virus' genetic code, find the new mutations and start producing copies of mRNA for new vaccines. This is a huge leap forward for vaccination. Effective vaccines can be designed in weeks rather than decades. There are fewer errors in production. They are cheaper to make. Take a moment to remember that COVID-19 first appeared around November 2019. The first COVID vaccines entered human clinical trials in March of 2020. That means scientists only needed a little more than 100 days to identify the disease, decode its genome, design a vaccine, produce the mRNA for the trial and start production. That's much faster than the vaccines of the past, and mRNA vaccines have a wide range of applications within disease. Scientists are working on mRNA vaccines for other diseases that have a high mutation rate, such as influenza or the flu, HIV, RSV and even certain forms of cancer. Vaccination has taken a long, incredible journey from the 1700s all the way to the modern era, and it stands as proof of the length people will go to to help their fellow humans in need. As one of the creators of the polio vaccine, Dr. Albert Sabin said, reflecting on his life and work, without human compassion, no knowledge is meaningful. The practice of medicine is a perfectly good example where compassion is an absolute ingredient. About 90 years ago, we probably had 90% compassion and 10% knowledge. There wasn't much knowledge to apply. Now there's so much knowledge to apply, there's almost no time for compassion. Knowledge without compassion is meaningless. Vaccines have gone through many different forms as research has improved, but the core science has always remained the same. If you can safely expose the immune system to a pathogen, then you can create immunity to that pathogen. The results have remained the same too. From smallpox to measles to polio to COVID, proper vaccination has always helped us prevent infectious disease and save lives. It's truly one of the greatest accomplishments in the history of humanity.