One way we can protect a child’s health (and those around them) is through immunization. The vaccines (given through injection) may cause a little discomfort, but the diseases they can prevent can cause a lot more harm. Immunization shots, also known as vaccinations, are essential. They protect against diseases such as measles, mumps, rubella, hepatitis B, polio, diphtheria, tetanus, and pertussis (whooping cough). Immunizations are important for both adults and children. Here’s why.
The immune system helps the human body fight germs by producing substances to combat them. Once it does, the immune system “remembers” the germ and can fight it again. Vaccines contain germs that have been killed or weakened, making them harmless. When given to a healthy person, the vaccine triggers the immune system to respond and thus build immunity.
Before vaccines, people became immune only by actually getting a disease and surviving it. Immunizations are a safer and more effective way to become immune.
Vaccines are the best defense we have against serious, preventable, and sometimes deadly contagious diseases. Vaccines are some of the safest medical products available, but like any other medical product, there may be risks. Accurate information about the value of vaccines, as well as their potential side effects, helps people make informed decisions about vaccination.
Figure \(\PageIndex{1}\): A nurse giving an infant vaccinations. Image by Maria Immaculata Hospital is licensed under CC BY-SA 4.0.
How Well Do Vaccines Work?
Vaccines work really well. No medicine is perfect, of course, but most childhood vaccines produce immunity about 90–100% of the time.
What about the argument made by some people that vaccines don’t work that well...that diseases would be going away on their own because of better hygiene or sanitation, even if there were no vaccines?
That simply isn’t true. Certainly, better hygiene and sanitation can help prevent the spread of disease, but the germs that cause disease will still be around, and as long as they are, they will continue to make people sick.
All vaccines must be licensed (approved) by the Food and Drug Administration (FDA) before being used in the United States, and a vaccine must go through extensive testing to show that it works and that it is safe before the FDA will approve it. Among these tests are clinical trials, which compare groups of people who get a vaccine with groups of people who get a control. A vaccine is approved only if the FDA determines that it is safe and effective for its intended use.
If you look at the history of any vaccine-preventable disease, you will virtually always see that the number of cases of the disease starts to drop when a vaccine is licensed. Vaccines are the most effective tool we have to prevent infectious diseases.
Potential Side Effects
Vaccines, like all medical products, may cause side effects in some people. Most of these side effects are minor, such as redness or swelling at the injection site. Read further to learn about possible side effects from vaccines.
Any vaccine can cause side effects. For the most part, these are minor (for example, a sore arm or a low-grade fever) and typically resolve within a few days.53 Serious side effects after vaccination, such as severe allergic reactions, are very rare.54
Remember, vaccines are continually monitored for safety, and like any medication, vaccines can cause side effects. However, a decision not to immunize a child also involves risk and could put the child and others who come into contact with him or her at risk of contracting a potentially deadly disease.
Opposition to Vaccines
In 2010, a pertussis (whooping cough) outbreak in California sickened 9,143 people and resulted in 10 infant deaths: the worst outbreak in 63 years (Centers for Disease Control, 2011). Researchers suspected that the primary cause of the outbreak was the waning effectiveness of pertussis vaccines in older children, recommending a booster vaccination for 11–12-year-olds and also for pregnant women (Zacharyczuk et al., 2011a; Zacharyczuk et al., 2011b). Pertussis is most serious for babies; one in five needs to be hospitalized, and since they are too young for the vaccine themselves, it is crucial that people around them be immunized (Centers for Disease Control, 2011). Several states, including California, have been requiring the pertussis booster for older children in recent years with the hope of staving off another outbreak.
But what about people who do not want their children to have this vaccine, or any other? That question is at the heart of a debate that has been simmering for years. Vaccines are biological preparations that improve immunity against a certain disease. Vaccines have contributed to the eradication and control of numerous infectious diseases, including smallpox, polio, mumps, chickenpox, and meningitis.
Figure \(\PageIndex{2}\): These two young children contracted polio. Image by the CDC is in the public domain.
However, many people express concern about potential negative side effects from vaccines. These concerns range from fears about overloading the child’s immune system to controversial reports about devastating side effects of the vaccines.56
Although children receive several vaccines up to their second birthday, these vaccines do not overload the immune system. Every day, an infant’s healthy immune system successfully fights off thousands of antigens – the parts of germs that cause their immune system to respond. Even if your child receives several vaccines in one day, vaccines contain only a tiny amount of antigens compared to the antigens your baby encounters every day.
This is the case even if your child receives combination vaccines. Combination vaccines are two or more vaccines that could be given individually, combined into one shot. Children get the same protection as they do from individual vaccines given separately, but with fewer shots.57
One common misapprehension is that the vaccine itself might cause the disease it is intended to immunize against.58 Vaccines help develop immunity by imitating an infection, but this “imitation” infection does not cause illness. Instead, it causes the immune system to develop the same response as it would to a real infection, allowing the body to recognize and fight the vaccine-preventable disease in the future. Sometimes, after receiving a vaccine, an imitation infection can cause minor symptoms, such as a fever. Such minor symptoms are normal and should be expected as the body builds immunity.59
Another commonly circulated concern is that vaccinations, specifically the MMR vaccine (MMR stands for measles, mumps, and rubella), are linked to autism. The autism connection has been particularly controversial. In 1998, a British physician named Andrew Wakefield published a study in Great Britain’s Lancet magazine that linked the MMR vaccine to autism. The report garnered significant media attention, leading to a decline in British immunization rates from 91 percent in 1997 to nearly 80 percent by 2003, accompanied by a subsequent rise in measles cases (Devlin, 2008). A prolonged investigation by the British Medical Journal revealed that not only was the link in the study nonexistent, but also that Dr. Wakefield had falsified data to support his claims (CNN, 2011). Dr. Wakefield was discredited and stripped of his license, but the doubt still lingers in many parents’ minds.
In the United States, many parents still believe in the now discredited MMR-autism link and refuse to vaccinate their children. Other parents choose not to vaccinate for various reasons, like religious or health beliefs. In one instance, a boy whose parents opted not to vaccinate returned home to the U.S. after a trip abroad; no one yet knew he was infected with measles.
The boy exposed 839 people to the disease and caused 11 additional cases of measles, all in other unvaccinated children, including one infant who had to be hospitalized.
Figure \(\PageIndex{3}\): A baby with measles. Image by CDC Global is licensed under CC BY 2.0.
According to a study published in Pediatrics (2010), the outbreak cost the public sector $10,376 per diagnosed case. The study further showed that the intentional non-vaccination of those infected occurred in students from private schools, public charter schools, and public schools in upper-socioeconomic areas (Sugerman et al., 2010).61
The Immunization Schedule
On-time vaccination throughout childhood is essential because it helps provide immunity before children are exposed to potentially life-threatening diseases. Vaccines are tested to ensure that they are safe and effective for children to receive at the recommended ages.62 Fully vaccinated children in the U.S. are protected against sixteen potentially harmful diseases. Vaccine-preventable diseases can be very serious, may require hospitalization, or even be deadly, especially in infants and young children.63
Here is the schedule from the CDC to ensure a child is fully vaccinated:
Figure \(\PageIndex{4}\): Immunization schedule. Image found on page 2 of the Color Schedule (pdf) by the CDC is in the public domain.
References, Contributors and Attributions
Centers for Disease Control and Prevention. (2011). Notes from the field: Pertussis—California, January–June 2010. Morbidity and Mortality Weekly Report, 59(26), 817. https://www.cdc.gov/mmwr/preview/mmwrhtml/mm5926a5.htm
