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Childhood Vaccinations


Michael J. Smith

, MD, MSCE, Duke University School of Medicine

Reviewed/Revised Aug 2023

Vaccination protects children against many infectious diseases. Vaccines contain either noninfectious components of bacteria or viruses or whole forms of these organisms that have been weakened so that they do not cause disease. Giving a vaccine (usually by injection) stimulates the body's immune system to defend against that disease. Vaccination is also called immunization because it produces a state of immunity to disease (see also Overview of Immunization Overview of Immunization Immunization (vaccination) helps the body defend itself against diseases caused by certain bacteria or viruses. Immunity (the ability of the body to defend itself against diseases caused by... read more ).

Childhood Vaccination Schedules

In the United States, childhood vaccination follows a schedule recommended by the Centers for Disease Control and Prevention (CDC), which begins with the hepatitis B vaccine Hepatitis B Vaccine The hepatitis B vaccine helps protect against hepatitis B and its complications ( chronic hepatitis, cirrhosis, and liver cancer). Generally, hepatitis B is more serious than hepatitis A and... read more given in the hospital nursery and continues throughout childhood:

Parents should try to have their children vaccinated according to the schedule. A significant delay in vaccination puts children at risk of the serious diseases the vaccines could prevent. If children miss a vaccine dose, parents should talk to their doctor about catching up with the schedule. Missing a dose does not require children to restart the series of injections from the beginning. The following schedule is used to catch up when behind on vaccinations:

Vaccination does not need to be delayed if children have a slight fever resulting from a mild infection, such as an ordinary cold.

Some vaccines are recommended only under special circumstances—for example, only when children have an increased risk of getting the disease the vaccine prevents.

More than one vaccine may be given during a visit to the doctor's office, and several vaccines are often combined into one injection. For example, there is a vaccine that combines pertussis, diphtheria, tetanus, polio, and Haemophilus influenzae type b vaccines in one injection. A combination vaccine simply reduces the number of injections needed and does not reduce the safety or effectiveness of the vaccines. (See also CDC: Multiple Vaccines at Once.)

Vaccine Effectiveness

Vaccination is effective in preventing serious disease. Without vaccines, children are at risk of becoming seriously ill or even dying from diseases such as measles and whooping cough. Vaccines have been so effective that many health care professionals currently in practice have seen few or no cases of diseases that were once extremely common and often fatal (see CDC: Diseases You Almost Forgot About Thanks to Vaccines).

Vaccines have eliminated smallpox Smallpox Smallpox is a highly contagious, very deadly disease caused by the variola virus. The disease is now considered eliminated. There have been no cases of smallpox since 1977. People can acquire... read more Smallpox and have nearly eliminated other infections, such as polio Polio Polio is a highly contagious, sometimes fatal enterovirus infection that affects nerves and can cause permanent muscle weakness, paralysis, and other symptoms. Polio is caused by a virus and... read more , that were once common causes of chronic health issues or death in children. However, many of the diseases prevented by vaccination are still present in the United States and remain common in some parts of the world. These infections can spread rapidly among unvaccinated children, who, because of the ease of modern travel, can be exposed even if they live in areas where a disease is not common. Therefore, it is important for children to continue to be vaccinated.

Vaccine Safety

Vaccines that are approved for clinical use are generally safe and effective. No vaccine (or other medication) is 100% effective and 100% safe. A few vaccinated children do not become immune, and a few develop side effects. Most often, the side effects are minor, such as pain and redness at the injection site, a rash, or a mild fever. Very rarely, there are more serious problems.

Vaccine Adverse Event Reporting System (VAERS)

Before a new vaccine can be licensed, it, like any medical product, is tested in clinical trials How Doctors Try to Learn What Works Doctors have been treating people for many thousands of years. The earliest written description of medical treatment is from ancient Egypt and is over 3,500 years old. Even before that, healers... read more . Such trials compare the new vaccine to a placebo or to a previously existing vaccine for the same disease to assess whether the vaccine is effective and identify common side effects. However, some side effects are too rare to be detected in any reasonably sized clinical trial and do not become apparent until after a vaccine is used routinely in many people. Thus, a surveillance system called the Vaccine Adverse Event Reporting System (see VAERS) was created to monitor the safety of vaccines that are used in the general public.

VAERS is a safety program cosponsored by the U.S. Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC). It is used to collect reports from people who believe that they had a side effect after a recent vaccination and from health care professionals who identify certain possible side effects after a vaccine was given, even if they are unsure the effects are related to the vaccine. Thus, the existence of a VAERS report is not proof that a vaccine caused a certain side effect. VAERS is simply a system for collecting data about things that might be side effects. Then, the FDA can further evaluate the concern by comparing how often the possible side effect occurred in people who were vaccinated to how often it occurred in people who were not vaccinated.

National Vaccine Injury Compensation Program

To help people evaluate the risks and benefits of vaccination, the US government requires doctors to give parents a Vaccine Information Statement each time a child is vaccinated. Also, the National Vaccine Injury Compensation Program has been established to compensate people with proven vaccine-related injuries. This program was established because doctors and health authorities want as many children as possible to be protected from life-threatening diseases.

When considering the risks and benefits of vaccination, parents must remember that for most children the benefits of vaccination far outweigh the risks.

More Information

The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.

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