Diphtheria
Diphtheria is a serious infection caused by bacteria that can make people very sick. One of the first signs is a sore throat, fever, and swollen neck 3. But what makes diphtheria especially dangerous is that it can cause a thick, gray pseudomembrane to form in the throat 3. This coating can block the airway, making it hard to breathe, and in some cases, it can even lead to choking. If the bacteria spread in the body, it can damage important organs like the heart and nerves. This can cause long-term problems or even death if not treated quickly 3.
Diphtheria spreads very easily from one person to another. It is usually spread through tiny droplets when someone who is infected coughs, sneezes, or talks 3. People nearby can breathe in these droplets and get sick. It can also spread by touching objects like toys or cups that have the bacteria on them, or by touching open sores from someone who has a skin infection caused by diphtheria 3.
People who are not vaccinated are most at risk. The disease spreads faster in crowded places like schools or shelters, especially when people are close together and don’t have strong protection from vaccines. That’s why getting the diphtheria vaccine is so important,it helps protect not only the person who gets it but also those around them by stopping the spread.
Diphtheria Vaccine
Scientists were desperate to find a way to stop Diphtheria. In the 1890s, German scientist Emil von Behring and his Japanese colleague Shibasaburo Kitasato made a major discovery12. They found that they could protect animals from diphtheria by injecting them with antibodies taken from other animals that had already fought off the disease12. This method was called serum therapy.
In 1895, Behring became the first person to try this treatment on humans 10. He gave the serum to children with diphtheria, and many of them recovered. Behring’s work was so important that he later won the first-ever Nobel Prize in Medicine in 1901 12.
But there was still a problem, serum therapy could only treat the disease after someone got sick. Scientists wanted to prevent it from happening in the first place 12,14. In the 1920s, French scientist Gaston Ramon discovered that he could use a chemical called formaldehyde to weaken the diphtheria toxin 12,14 . This allowed him to create a safe and effective vaccine that could protect people before they got infected. Ramon's method made it possible to produce the vaccine in large amounts, helping diphtheria cases drop sharply in the decades that followed.
Tetanus
Tetanus, also known as lockjaw, is a serious disease caused by bacteria that live in soil, dust, dirt, and even in animal or human poop (feces)⁴. These bacteria are everywhere in the environment and can enter the body through cuts, scrapes, burns, or deep wounds, especially if the injury is dirty or made by something like a rusty nail.
Once inside the body, the bacteria produce a powerful toxin that affects the nerves. This toxin can cause painful muscle spasms, especially in the jaw and neck, which is why the disease is called "lockjaw." Other symptoms include headaches, fever, sweating, seizures, stiff muscles, high blood pressure, and a fast heartbeat⁴. The muscle stiffness can get so bad that people have trouble opening their mouths, swallowing, or even breathing. If tetanus is not treated quickly with the right medicine, it can lead to death⁴.
Although anyone can get tetanus, young children, older adults, and people who have not been vaccinated are most at risk. Unlike many other diseases, tetanus does not spread from person to person, because the bacteria enter the body through wounds. You can only get it when bacteria enter your body through a wound, so it's important to clean cuts well and get medical help when needed.The best way to protect yourself is through vaccination.
Tetanus Vaccine
In the 1890s, scientists Emil von Behring and Shibasaburo Kitasato also worked on tetanus. They found that animals could be protected from tetanus in the same way as diphtheria by using serum therapy12, . Around the same time, veterinarian Edmond Nocard used the serum to protect horses from tetanus, which was a big deal because horses were essential for farming and transportation12,.
After World War I, doctors used tetanus serum to help wounded soldiers, many of whom had deep injuries from the battlefield12. This treatment saved lives, but it wasn’t easy to make or store the serum for large numbers of people. Once again, in the 1920s, Gaston Ramon stepped in. Using the same technique he used for diphtheria, Ramon treated the tetanus toxin with formaldehyde to make it safe12,14. This led to the creation of the tetanus toxoid vaccine, which could protect people ahead of time rather than waiting for them to get sick. The vaccine was first widely used in World War II to protect soldiers, and it worked so well that it became part of regular vaccinations for children.
Pertussis
Pertussis, also called whooping cough, is a serious infection caused by a type of bacteria called Bordetella pertussis². It mainly affects the lungs and breathing tubes, making it hard to breathe, especially for young children. In Canada, about 1,000 to 3,000 people get pertussis every year². Although anyone can catch it, babies and young children are at the highest risk of getting very sick from it. At first, pertussis can seem like a regular cold. People may have a low fever, a runny nose, red or watery eyes, and feel tired². But after a few days, it gets much worse. The illness causes long and painful coughing fits that can last from 2 to 8 weeks or even longer². During these fits, people may have trouble catching their breath, and they might even turn red or blue in the face. Some people make a loud "whooping" sound when they try to breathe in after coughing, this is where the name "whooping cough" comes from.
In severe cases, especially in babies, the coughing can lead to vomiting, swelling in the throat, and even choking or stopping breathing. These symptoms can be very dangerous and sometimes require treatment in a hospital 2.Pertussis is also very contagious, which means it spreads easily from one person to another. It spreads through the air when someone who is infected coughs or sneezes, and people nearby breathe in the germs22. This is why pertussis often spreads quickly in places like homes, daycares, and schools especially when people are not vaccinated².The best way to protect yourself and others is by getting vaccinated.
Pertussis Vaccine
Scientists first discovered the bacteria that causes pertussis,in 1906 12,14. This was a big step forward because it helped doctors understand what was making children so sick. Not long after, in 1914, early versions of a pertussis vaccine were created12,14. These first vaccines gave people hope, but they weren’t perfect. They were difficult to make in large amounts, and the results weren’t always the same for every person who got the shot12,14. At that time, pertussis was causing many infant deaths around the world12,14. Families were heartbroken as babies struggled to breathe during long, painful coughing fits. It was clear that a stronger, more reliable vaccine was needed.
In the 1920s, scientists in Denmark worked on improving the vaccine. They studied the toxins (poisonous parts) released by the pertussis bacteria and figured out how to better prepare the vaccine so it would be safer and work more effectively12,14. This led to a new generation of pertussis vaccines.
Then in the 1930s, an American scientist named Dr. Pearl Kendrick, along with her team, made a huge difference. They developed what’s known as the whole-cell pertussis vaccine, which used the entire (but killed) bacteria to train the immune system to fight off the real infection12,14. Dr. Kendrick also led large-scale public trials, testing the vaccine in schools and communities to see how well it worked12,14. These tests were some of the first of their kind and helped prove that vaccines could safely and effectively protect children.By 1944, the vaccine was working so well that the American Academy of Pediatrics officially recommended that all children get vaccinated against pertussis12,14.. This marked a turning point in the fight against whooping cough, helping to save countless lives and giving parents peace of mind12,14
Tdap Vaccine Development and Historical combination
Even though diphtheria, tetanus, and pertussis (whooping cough) never caused worldwide pandemics like COVID-19, they used to be some of the leading causes of death in babies and young children 18 Before vaccines, families lived in fear of these serious infections. Today, thanks to vaccines like DTaP (for children) and Tdap (for teens and adults), people are protected from all three of these dangerous diseases⁷.
All three diseases are caused by bacteria that release harmful toxins, which are poisons that make people sick 8. To create the vaccine, scientists use a chemical process to weaken these toxins so they can’t cause illness. These harmless versions are called toxoids 8. When toxoids are injected into the body, the immune system reacts by building up protection, so if the real disease shows up later, the body knows how to fight it off 8.Instead of giving three separate vaccines for each disease, scientists figured out how to combine the diphtheria, tetanus, and pertussis toxoids into a single shot 8. This combination vaccine was helpful because it made it easier for people, especially children, to get the protection they needed without having to take multiple shots11. The combination vaccines also helped people get vaccinated more regularly.
Gaston Ramon observed that stronger local reactions at the injection site were associated with better immune responses, which inspired the use of adjuvants. Shortly after, Alexander Glenny and colleagues (1926) demonstrated that aluminum salts (alum) could be used as effective adjuvants for diphtheria toxoids. Adjuvants helped make vaccines stronger, and they also made it possible to combine different antigens (the parts of a germ that trigger immunity) into one shot6,10. This helped lower the number of needles people needed, which made getting vaccines more acceptable and easier for the public.
The first ever combination vaccine was made for influenza in 1945, and just a few years later, the DTP vaccine which protects against diphtheria, tetanus, and pertussis was introduced in 1948 6,10. This was a huge step forward in public health.
The original DTP vaccine used a whole-cell pertussis component, meaning it included the entire killed bacteria 7 It worked well, but it also caused some unwanted side effects, like fever, swelling, and soreness 7. These side effects were more common and sometimes made parents worry about getting their kids vaccinated.
To fix this problem, Dr. Margaret Pittman suggested making a safer version of the pertussis vaccine7,20. Inspired by her idea, Dr. Yuji Sato in Japan developed the first acellular pertussis vaccine, which only used parts of the bacteria, not the whole thing 7. This version caused fewer side effects and was much better tolerated by children.
In the 1980s, more research and trials were done to make the acellular vaccine even better⁶. By the 1990s, the older DTP vaccine was replaced with DTaP for children. Tdap, a reduced-antigen formulation for adolescents and adults, was introduced in the mid-2000s and is now routinely used for boosters.7 These newer versions are the ones we use today, and they continue to protect millions of people from diphtheria, tetanus, and whooping cough every year.
Who Gets the DTaP and Tdap Vaccines?
The DTaP vaccine is given to babies and young children to protect them from diphtheria, tetanus, and pertussis (whooping cough)5,18. The vaccine is given in a series of five doses: at 2 months, 4 months, 6 months, 15 to 18 months, and again between 4 to 6 years old5,18. The first three shots help build strong protection, and the last two are booster shots to keep the immune system ready to fight these diseases.
As children grow older, they get a different version called Tdap, which has smaller amounts of diphtheria and pertussis antigens. This helps reduce the chances of side effects in preteens, teens, and adults5,18. Tdap is usually recommended around age 11 or 12, and adults should get a booster shot every 10 years, especially after an injury like a deep cut or scrape5,18.
In Canada, NACI recommends Tdap during each pregnancy, ideally at 27–32 weeks’ gestation to maximize antibody transfer, but it can be given as early as 13 weeks and up to delivery if needed⁵. This helps moms pass on temporary immunity to their babies before birth, keeping them safe until they are old enough for their own vaccines.
Why Vaccination Matters for Everyone?
Vaccines like DTaP and Tdap do more than protect individuals,they protect entire communities. When lots of people are vaccinated, it becomes harder for diseases to spread. This is called herd immunity15. It’s especially important for people who can’t get vaccinated because of health conditions;they're protected when the people around them are immune15.
Vaccines also help reduce the need for antibiotics, which is important because overusing antibiotics can lead to antibiotic resistance,a serious problem that makes infections harder to treat15. By preventing disease in the first place, vaccines keep our medical treatments working longer and more effectively.
Getting vaccinated also helps families avoid the emotional stress, time off school or work, and medical costs that come with serious illness15. When children stay healthy, they can go to school, play with friends, and enjoy a normal childhood without interruption. Because of vaccines, people today live longer, healthier lives, and deaths from diseases like diphtheria, tetanus, and whooping cough are now very rare¹¹.
Understanding Vaccine Hesitancy
Some people today are still unsure about TdaP vaccines. Back in the 1960s, there were reports that the older DTP vaccine caused serious side effects, including problems with the nervous system15. This caused many parents to become worried, even though later studies showed that the risks were very small.
Since then, scientists have made big improvements. The newer DTaP and Tdap vaccines are much safer and have fewer side effects. But even today, some people still feel nervous about vaccines because of misinformation, cultural beliefs, or fears about ingredients like preservatives15. Social media and rumors can also spread confusion and fear, even when the science says vaccines are safe.
While it’s okay to ask questions, it’s important to look for trustworthy information from doctors and public health experts. Not getting vaccinated puts people at much greater risk of getting seriously ill. That’s why encouraging vaccination through education and honest conversations is so important.
Conclusion
The Tdap vaccine plays a powerful role in protecting people from three serious diseases that once caused a lot of pain and death, especially in children. Thanks to the hard work of scientists and doctors over the years, we now have safe, effective vaccines that protect millions of people every day.
Even though some people are still unsure about vaccines, the benefits of immunization are much greater than the risks. When we get vaccinated, we’re not just protecting ourselves,we’re protecting our families, our communities, and future generations. That’s why staying informed and encouraging others to get vaccinated remains an important step in keeping everyone healthy.
References
¹Anyiwe, K., Richardson, M., Brophy, J., & Sander, B. (2020). Assessing adolescent immunization options for pertussis in Canada: A cost-utility analysis. Vaccine, 38(7), 1825–1833. https://doi.org/10.1016/j.vaccine.2019.12.021
²Canada, Public Health Agency of. (2002, October 19). Pertussis (whooping cough). https://www.canada.ca/en/public-health/services/immunization/vaccine-preventable-diseases/pertussis-whooping-cough.html
³Canada, Public Health Agency of. (2014, July 24). Diphtheria. https://www.canada.ca/en/public-health/services/immunization/vaccine-preventable-diseases/diphtheria.html
⁴Canada, Public Health Agency of. (2014, October 8). Tetanus. https://www.canada.ca/en/public-health/services/immunization/vaccine-preventable-diseases/tetanus.html
⁵Canada, Public Health Agency of. (2018, February 28). Update on immunization in pregnancy with Tdap vaccine. https://www.canada.ca/en/public-health/services/publications/healthy-living/update-immunization-pregnancy-tdap-vaccine.html
⁶Celebrating Gaston Ramon – the vet behind vaccinology’s secret weapon. (2019, April 24). World Economic Forum. https://www.weforum.org/stories/2019/04/gaston-ramon-vaccination-secret-weapon-adjuvanted/
⁷Cherry, J. D. (2019). The 112-year odyssey of pertussis and pertussis vaccines—Mistakes made and implications for the future. Journal of the Pediatric Infectious Diseases Society, 8(4), 334–341. https://doi.org/10.1093/jpids/piz005
⁸Children’s Hospital of Philadelphia. (n.d.). Diphtheria, tetanus and pertussis: The diseases & vaccines. Retrieved July 2, 2025, from https://www.chop.edu/vaccine-education-center/vaccine-details/diphtheria-tetanus-and-pertussis-vaccines
⁹Children’s Hospital of Philadelphia. (n.d.). Vaccine history: Developments by year. Retrieved July 14, 2025, from https://www.chop.edu/vaccine-education-center/science-history/vaccine-history/developments-by-year
¹⁰Chippaux, J.-P. (2024). Gaston Ramon’s Big Four. Toxins, 16(1), 33. https://doi.org/10.3390/toxins16010033
¹¹Edwards, K. M., & Decker, M. D. (2001). Combination vaccines. Infectious Disease Clinics of North America, 15(1), 209–230. https://doi.org/10.1016/S0891-5520(05)70276-2
¹²Kaufmann, S. H. E. (2017). Remembering Emil von Behring: From tetanus treatment to antibody cooperation with phagocytes. mBio, 8(1), e00117-17. https://doi.org/10.1128/mBio.00117-17
¹³Liang, J. L., Tiwari, T., Moro, P., Messonnier, N. E., Reingold, A., Sawyer, M., & Clark, T. A. (2018). Prevention of pertussis, tetanus, and diphtheria with vaccines in the United States: Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recommendations and Reports, 67(2), 1–44. https://doi.org/10.15585/mmwr.rr6702a1
¹⁴Marks, H. M. (2007). The Kendrick-Eldering-(Frost) pertussis vaccine field trial. Journal of the Royal Society of Medicine, 100(5), 242–247. https://doi.org/10.1258/jrsm.100.5.242
¹⁵Montero, D. A., Vidal, R. M., Velasco, J., Carreño, L. J., Torres, J. P., Benachi O., M. A., Tovar-Rosero, Y.-Y., Oñate, A. A., & O’Ryan, M. (2024). Two centuries of vaccination: Historical and conceptual approach and future perspectives. Frontiers in Public Health, 11, 1326154. https://doi.org/10.3389/fpubh.2023.1326154
¹⁶Muloiwa, R., & Forsyth, K. D. (2025). Closing the pertussis immunity gap: Vaccine equity saves infant lives. The Lancet Infectious Diseases, 0(0). https://doi.org/10.1016/S1473-3099(25)00109-4
¹⁷Ramon, Gaston—Document—Gale eBooks. (n.d.). Retrieved July 22, 2025, from https://go-gale-com.myaccess.library.utoronto.ca/ps/i.do?p=GVRL&u=utoronto_main&id=GALE%7CCX2830903572&v=2.1&it=r&cookieConsent=true&analyticsOptout=false&aty=ip
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By Farhana Bhanji