In this video series, physicians at The Children's Hospital of Philadelphia explain how vaccines work and how they are made, and describes several vaccines and the diseases they prevent. Families share their stories of children affected by vaccine-preventable diseases.
Introduction: Vaccines and Your Baby
Paul A. Offit, MD : New parenthood can be an overwhelming time for a family. We're so focused on trying to do what's right for this little baby who's depending on us, and suddenly we're faced with all these complicated questions. Thanks to modern science, parents are required to make choices about the best ways to feed and shelter, clothe and transport their children. But today we're going to talk about one way that modern science has made childhood easier, more predictable, and less perilous than ever before —vaccines.
Our mission here at the Vaccine Education Center is to talk to parents about vaccines, how they work, how they're made, and how they've been proven to be safe and effective. Of course, that also means talking about the diseases that vaccines prevent. Now, some of these diseases are pretty rare in our part of the world, but others are still surprisingly common.
Before the Chickenpox Vaccine
Patrice Sport, parent : I just assumed that it was the chickenpox. So I took him to the doctor, and the doctor said, "He has the chickenpox." I was like, "Oh my God." You know, he's going to have all these marks all over his face. I'm going to have to go to the store and buy the pink Calamine lotion. And we're going to have to do the oatmeal baths and the itching and the crying. So I went home expecting, you know, this big outbreak. And it wasn't. I watched him for a day or two, and, you know, nothing ever happened.
Marina Catallozzi, MD : Some children never even know they have chickenpox. They have no symptoms at all. No blisters, no fever, no problems. But unfortunately, most children aren't so lucky.
Francesca Mattone, parent : Two weeks after Nicky had chickenpox, Matthew started. Matthew really had a lot of chickenpox right from the start. He would get hundreds at a time. And for about four or five days, he had high fevers that never came down. I had him in the tub just to get down the fever 2 or 3 times a day. He didn't even scratch. He just kind of laid in my arms. He was very, very sleepy. I would get him to drink, but he didn't eat. He had chickenpox in his mouth. He had chickenpox inside his ears. He had about 2-300 chickenpox just on his head. And he was just miserable.
Marina Catallozzi, MD : So, typically, children who get chickenpox get about 300 to 500 blisters, fever, and intense itching. But for some, it can be even worse.
Carol Pugh, parent : It was just a normal breakout of chickenpox, and one got severely infected under his arm. But it was just that one chickenpox. That's all it took. It turned into a flesh eating disease. It was just a clear hole. You could see straight to the muscle, which we had to keep bandaged. He was very sick. He could have lost his arm. He could have died. It could have been really bad.
Marina Catallozzi, MD : You know, the story isn't so unusual. Before the vaccine, about 10,000 people were hospitalized and 100 killed by chickenpox every year. But regardless of whether chickenpox causes mild, moderate, or severe disease, almost all children who get chickenpox will be protected against it for the rest of their lives. They're said to be immune. The difference is that children with serious infections pay a very, very high price for their immunity.
How Vaccinations Cause Immunity to Infectious Diseases
Paul A. Offit, MD : As parents we don't want our children to pay a high price for immunity. That's where vaccines come in. Vaccines give immunity without making children suffer the risks of natural infection.
Louis M. Bell, MD : Let's continue with our example of chickenpox. Chickenpox is caused by a virus. Children first come into contact with chickenpox virus when someone who is infected coughs or sneezes. The virus travels through the air in tiny droplets and lands on the lining of the nose or the back of the throat. The virus then begins to copy itself over and over again until it spreads into the bloodstream and eventually to the skin where it causes a rash.
However, as we've seen in some children, chickenpox virus doesn't grow very well. These children don't get very sick at all. But having been exposed to the virus, all of these children have one thing in common, they are now immune to the disease; and having this immunity means that they will not get a serious case of chickenpox again. Getting the chickenpox vaccine is just like getting a mild chickenpox infection. You get virtually no symptoms and long-lasting immunity without having to risk the occasionally severe consequences of natural infection.
What is a Virus in the Body?
Kathleen Sullivan, MD : In order to understand how vaccines are made, we must first understand how viruses work. Viruses are constructed kind of like these.
But unlike hard candy, the shell of the virus is made of protein and instead of chocolate, the center of the virus consists of genes. Genes are simply blueprints that tell viruses how to duplicate or reproduce themselves.
How the Chickenpox Vaccine Works
Kathleen Sullivan, MD : Here's how the chicken pox vaccine was made. The chickenpox virus was taken from a little boy with chickenpox in Japan in the 1960s. The chickenpox virus was then grown in specialized cells in the laboratory. As the virus got better and better at growing in the laboratory, it got worse and worse at growing in children. So the chickenpox vaccine represents the very best of two worlds. On the one hand, the vaccine virus doesn't grow very well in children, so it doesn't cause disease. On the other hand, the vaccine virus grows well enough to provide the shield of long-lasting immunity.
Christina L. Master, MD : He looks beautiful. You're doing a wonderful job with him.
The next vaccine that we're going to talk about is usually the first vaccine that babies get. It's given to prevent a common infection of the liver.
Why the Hepatitis B Vaccine Is Important
Christina L. Master, MD : People usually get infected with the hepatitis B virus when they're teenagers or young adults, but newborn babies can catch it during delivery if their mothers are infected. And young infants and older children can catch it from an infected sibling or playmate or relative.
Trish Parnell, Director of PKIDS : We have a lot of information that we're going to send you. You're going to go through so much-- When parents first find out that their child is living with a disease like hepatitis B, it is a life-altering discovery. The parents when they find out, they're angry, they're terrified, they're heart just shatters, because their kids' lives are not going to be what every parent dreams of, which is you--the kids are happy, they go to school, they're totally healthy, they grow up, they have kids of their own, and they live long healthy lives. That's probably not going to happen with kids who are chronically infected with hepatitis B.
Christina L. Master, MD : Every year many people in the United States die from a rapid and overwhelming infection of the liver caused by hepatitis B virus. Some people die from a long-term liver disease called cirrhosis. Still other people die from liver cancer. In fact, the only known agent that causes more cases of cancer than cases of hepatitis B virus is tobacco.
Trish Parnell, Director of PKIDS : There's this one family in Indiana, the mom died of liver cancer. Her two children are now grown. The son has died of liver cancer. The daughter is living with multiple problems from this disease, and of her kids, of her two kids, one of them is also chronically infected with hepatitis B because it wasn't until the third generation- well who knows how many generations before that- but it wasn't until the youngest generation that they found out that they had this disease. They just thought they were dying of cancer. They didn't know it was a preventable disease.
Christina L. Master, MD : People can be infected with hepatitis B virus and not even know it. You can't often tell who is contagious and who isn't. That's why it's important to get the vaccine. About 1 million people in the United States are infected with hepatitis B virus.
The hepatitis B vaccine is made using only the surface protein of the virus. Because we use only the coat of the virus, children can be protected without ever having to suffer the disease.
Trish Parnell, Director of PKIDS : It's just a simple shot, and your kids are protected. When a disease is preventable and the child is- the child's life is forever affected by it, it is just the most heartbreaking thing in the world.
Christina L. Master, MD : Although it's only been in routine use since the early 1990s, the incidence of disease caused by hepatitis B virus has already started to decline.
Narrator : The next vaccine we're going to talk about is given to prevent a common and severe bacterial infection of young children.
Why the Pneumococcal Vaccine Is Important
Amanda D. Castel, MD : Pneumococcus is a bacteria that causes meningitis, which is an infection of the brain and spinal cord. Pneumonia, which is an infection of the lungs and bloodstream infections, also known as sepsis. The pneumococcal vaccine was first used for babies in the United States in the year 2000. Before that, pneumococcus caused thousands of severe infections every year in young children, and some families are still coping with the consequences of those infections.
Alan MacKenzie, parent : Yeah, I can remember we had an earache, then it was sort of a severe earache. Then it was nausea, and he could not keep anything down, and we were starting to be dehydrated. Then it was Collin hallucinating, and we knew we were in serious trouble. Then the doctors are starting to, at the Emergency Room, were showing some very serious concern. And we start hearing of things that, you know, superficially sound terrible, but we don't know anything. It is a our first child. We had no idea what meningitis was.
Mary Ellen, parent : They had a confirmation through a spinal tap that Collin had a white cell count of 26, that they could not guarantee us he was going to live.
Alan MacKenzie, parent : The doctors are still saying, "It's all probability. You're not out of the woods yet. Something could happen. You know, just be emotional prepared for it." And it was really towards the ends where I thought we were beyond it all. We had been out of the emergency for a bit, and he seemed to be getting a little better. And then he had a terrible headache one night, and he was complaining of severe pain outside his ear. And I think that's when he lost the hearing in that ear.
Mary Ellen, parent : So many people say to us, why is this still a tragedy four years later? I think you should be grateful. And the truth of the matter is, we are incredibly grateful. But Collin is profoundly deaf in the left ear.
Alan MacKenzie, parent : Once you've lost hearing in one ear, the concentration is very difficult. You can't automatically filter out background noises. All noise is coming through. So imagine a movie where you really couldn't hear the main character speak because the traffic and everything else was the same volume. That's his life.
Amanda D. Castel, MD : So how do we keep pneumococcus from harming our children? The bacteria pneumococcus is covered by a complex sugar. The pneumococcal vaccine is made by taking the sugar coat, stripping it away from the bacteria, and attaching it to a helpful protein. Now, children can develop immunity to pneumococcus without ever having to risk infection in the actual bacteria.
Paul A. Offit, MD : Just like the pneumococcal vaccine, the next vaccine prevents what was at one time a very common cause of bacterial meningitis.
How the Hib Vaccine Has Helped Alleviate Meningitis
Paul A. Offit, MD : Hib vaccine was first used in the late 1980s. At that time the Hib bacteria was the most common cause of meningitis in this country. During my training, I saw children come into the hospital every week with meningitis caused by Hib. Some of these children were left blind, deaf, or learning disabled. Because Hib and pneumococcal bacteria are very similar, the Hib vaccine is made in the exact same way as the pneumococcal vaccine. Now, because of the Hib vaccine, we no longer have tens of thousands of cases of Hib every year. Young doctors in training don't have to see what I saw.
What the DTaP Vaccine Is and Diseases It Prevents
Louis M. Bell, MD : Thank you. That's better. That's a little better.
The next vaccine that we're going to talk about is really three vaccines in one. Because we are able to easily combine these vaccines, children can get one shot instead of three.
The vaccine is called DTaP. Let’s start with the D. When my father was a child this bacterial infection was one of the most common killers of teenagers. Diphtheria causes a thick coating at the back of the throat that makes it difficult for children to swallow and breathe. While it's growing in the throat the bacteria makes a harmful protein, a poison called a toxin, that attacks the heart, as well as the kidney and also the nervous system. Now because of the diphtheria vaccine only about two to five children get diphtheria every year in the United States. But the disease continues to occur in other parts of the world. Because international travel is common, the diphtheria vaccine is still important for our children.
The second letter of DTaP vaccine is T for tetanus. Tetanus is the only vaccine that prevents an infection that is not transmitted from one person to another. Tetanus bacteria live in the soil and enter the body after a cut or a puncture wound. Tetanus, like diphtheria, is a bacterium that makes a toxin, the tetanus toxin invades the muscles and causes strong and painful muscle spasms. The infection is also known as lock jaw because the toxin can affect the muscles of the jaw. Every year some people in the United States get tetanus and die from the disease. Because the tetanus bacteria will always be present in the soil, the possibility of infection will never be eliminated; so it's important to be immunized.
The last letter of the DTaP vaccine is P for pertussis, an infection with a very recognizable sound. [sound of baby coughing] pertussis as a bacterium that causes a thick sticky mucus that clogs the windpipe. Children infected with pertussis bacteria cough repeatedly, often turning blue before they breathe in.
Lisa Rae, parent : The coughing episodes, I mean, sometimes they lasted, you know, for a minute and a half. And that minute and a half is the longest minute and a half you can imagine.
Louis M. Bell, MD :When they breathe in against their narrowed windpipe, they make a whooping sound. That's why the disease is also known as "whooping cough."
Lisa Rae, parent : There was one time, probably for about two days where they weren't sure. The infectious disease specialist came in and he said, "You know, I've treated a lot of pertussis cases." He said, "This is a serious one." He said, "I can't give you any guarantees." And that probably was the hardest thing for me to hear.
Louis M. Bell, MD : Although some parents may think that whooping cough is a rare disease in the United States, it isn't. Every year many adults get pertussis. If you've ever had a cough that lasted longer than five days, you may well have had it. And if you have children, they can easily catch it from you.
Lisa Rae, parent : As we walk along the streets now, I hear someone coughing, and my husband and I will look at each other, "Oh, that person may have pertussis and not know it."
Louis M. Bell, MD : Although the three diseases we just talked about, diphtheria, tetanus, and pertussis are all very different, the bacteria that cause these diseases share one thing in common. They all make harmful proteins called toxins. To be protected against these diseases, you need to have immunity to the toxins. So how can you get immunity to the toxins without being hurt by them? Toxins are first purified away from the bacteria and then made harmless by a chemical. These harmless toxins are called toxoids. Toxoids give children immunity to the toxins without causing them to suffer these terrible diseases.
The MMR Vaccine Prevents Three Viruses
Susan Coffin, MD : Hey, Jill, how are you?
Jill : Hi, Dr.Coffin
Susan Coffin, MD : Good to see you again.
Jill : Nice to see you too.
Susan Coffin, MD : Another vaccine that's really three vaccines in one is called MMR. The first M stands for disease that was once so common almost all children in the United States were infected by the time they were 10 years old. Measles is a virus that causes a rash that usually starts on the face and then spreads to the rest of the body. Most children who are infected recover fully. But before the measles vaccine, thousands of American children died each year from measles. They died because measles infected the brain, or they died because it infected their lungs. Now, about 9 out of every 10 children in the United States are immunized. And the incidence of measles infections has fallen dramatically. But because the measles epidemics have occurred in the U.S. as recently as 1991, we still need to keep our guard up.
The second M in the MMR vaccine stands for disease that caused children to have swelling of their cheeks that made them look like little chipmunks. Mumps is also caused by a virus. This virus usually infects the glands located just in front of the ear. These are called the parotid glands. Most children survive mumps infection without any difficulties. But infection with mumps isn't always so mild. That's because the mumps virus can also infect the brain and cause meningitis and deafness. In fact, mumps infections were one of the most common causes of deafness in the U.S. Now, because of the mumps vaccine, the infections caused by mumps virus have been significantly reduced. But mumps isn't gone. Every year cases of mumps still occur in the U.S.
The R in the MMR stands for a viral infection that was once a very common cause of severe birth defects. Rubella is a virus that typically infects children, causing a very mild illness with rash, low-grade fever, and swelling of the glands behind the ear. Children virtually always recover from rubella without any long-term problems. But when rubella infects pregnant women, the results are usually catastrophic. Most pregnant women infected with rubella early in their pregnancy either miscarry or deliver babies that are blind, deaf, or have heart defects. Before the rubella vaccine was used in the U.S., as many as 20,000; newborns every year were harmed by the rubella virus. 20,000 children. Now, because of the rubella vaccine, children are rarely harmed by the virus. The measles, mumps, and rubella vaccine are all made the exact same way as the chicken pox vaccine. Natural measles, mumps, and rubella viruses were first isolated from people and then weakened in the laboratory.
The Importance of the Polio Vaccine
Paul A. Offit, MD : The next vaccine prevents a disease that most of us have heard of, but few of us have ever seen.
In the 1940s and 1950s, polio routinely paralyzed thousands of children and adults every year. Among them are a president of the United States, Franklin Delano Roosevelt. After an urgent search to find a way to prevent this infection, the first polio vaccine was made by a doctor named Jonas Salk. Dr. Salk made the polio vaccine by purifying polio virus and then making it harmless by adding a chemical that completely killed the virus. The success of the polio vaccine has been remarkable. No cases of natural polio have occurred in the United States since 1979 and the last case of natural polio in the entire Western Hemisphere occurred in Peru, in 1991. Unfortunately, because polio occurs regularly in some parts of the world, it's still important to get the vaccine.
Do Vaccines Have Side Effects?
Dennis A. Brooks, MD : All vaccines have some side effects. Usually, the side effects are mild, like pain or redness or tenderness or even some swelling at the site where the shot is given. But some vaccines have more severe side effects. For example, the pertussis or whooping cough vaccine is a very rare cause of persistent, inconsolable crying. Crying can last longer than three hours and can be very frightening for both the parent and the child. About 1 of every 10,000 doses of pertussis vaccine will cause a child to experience this problem. So a parent could reasonably ask, "Why not just avoid any risk and simply not give the pertussis vaccine?" The answer is that a choice not to give a vaccine is not a risk-free choice. It is simply a choice to take a different and much more serious risk, the risk of getting pertussis, a disease that infects thousands of children every year, some of whom will die from it. You could think of a vaccine as being like a seat belt. Certainly, there is a small risk that in an accident your child's seat belt could cause a minor injury. That's a side effect of wearing one, but measured against a far more serious consequences of not wearing a seat belt, it's a risk every parent should be willing to take.
How are Vaccines Tested for Safety?
Paul A. Offit, MD : Another question parents ask is, "How do we know vaccines are safe?" Vaccines are evaluated for safety in three ways: First, vaccines cannot be given to any child in the United States until they are first approved or licensed by the Food and Drug Administration. In order to be licensed, a vaccine must be evaluated in a laboratory and then in thousands and thousands of children over a period of many years. Because vaccines are intended for healthy children, they are held to the highest standards of safety.
Georges Peter, MD : The next step in the approval process for these vaccines is the recommendations. These recommendations are made by three different groups who work closely together. For more than 20 years I have worked with two of these groups. And I can tell you that when the doctors and public health professionals and scientists study and analyze the information, we ask three basic questions: First, does the vaccine work? In other words, does it prevent the disease? Secondly, is the vaccine safe? Third, do we have all the information we need to answer these questions of vaccine safety and effectiveness? But the guiding principle, the bottom line, is would we give this vaccine to our patients, our children, and our grandchildren? If the answer is "yes," then we recommend the vaccine.
Benjamin Schwartz, MD : Although vaccines are usually tested in tens of thousands of children before approval, that still may not be enough to detect very, very rare side effects. For that reason, we do something called post licensure monitoring. The Centers for Disease Control and the Food and Drug Administration regularly send out a reporting form to doctors and nurses, which they can use to report any health problems that they think might be caused by a vaccine. This is called the Vaccine Adverse Events Reporting System or VAERS. Parents also can report to VAERS. But VAERS and other studies are only two of the many ways by which the safety of vaccines is monitored.
Can Babies Handle Vaccines So Young?
JoAnne Woehling, MD : In the first two years of life, you'll be visiting your baby's doctor fairly often. And during those visits, we'll talk about what your baby should be eating and what to expect as the baby gets older. We'll also talk about vaccines. During some visits, your baby could get several shots at one time. But as upsetting as it can be to watch your child go through this, the truth is your baby's already been through much tougher challenges.
From the moment of birth, babies immediately encounter thousands and thousands of bacteria that live in the lining of their skin, nose throat, and intestines. So how do they manage all of these bacteria? The answer is that babies have immune systems that are amazingly strong and adept. We all have the capacity to respond to hundreds of thousands of different challenges to our immune systems at one time. So the vaccines given in the first two years of life are just a tiny fraction of what babies encounter and successfully manage every day.
Paul A. Offit, MD : You know, that with everything that you have to think about right now, this probably seems like a lot of information. But really of all the facts we've talked about, the one that matters the most is this: After food and shelter, vaccines are probably the best way we have of keeping our children safe and well and free from harm.
Related Centers and Programs: Vaccine Education Center
Last Reviewed on Jul 23, 2014