Introduction:

Immunizations against childhood diseases save millions of lives. American vaccination rates are now at an all-time high. Disease and death from diphtheria, pertussis, tetanus, measles, mumps, rubella, and Haemophilus influenzae (H. influenzae) type b are at or near record lows. In adults, immunizations against influenza (the flu), pneumococcal pneumonia, hepatitis, and other ailments have likewise saved many lives and prevented many cases of serious illness. A new vaccine has been shown to be highly effective for preventing the virus that leads to cervical cancer.

More than 70 bacteria, viruses, parasites, and other infectious microbes cause major human disease. Fortunately, vaccines are either available or being developed against a portion of them. With the advent of new or newly feared biological threats, emerging infections, and bacterial resistance to common antibiotics, immunizations are assuming an increasingly important role in maintaining the health of billions of people worldwide.

Immunizations (vaccinations) are given to initiate or augment resistance to an infectious disease. Immunizations provide a specialized form of immunity that provides long-lasting protection against specific antigens, which cause disease.

Vaccine Forms

Most vaccines are given by an injection, but some can be taken orally (by mouth) or by a nasal spray. They usually contain one of four components that cause an immune response:

• A live but weakened virus. Live-virus vaccines provide longer immunity than inactivated ones, but they can cause serious infection in people with weakened immune systems and have also been associated with severe medical disorders in rare instances.
• Inactivated bacteria, viruses, or toxoids. Inactivated vaccines are safe even in people with impaired immune systems.
• A toxoid, which is a harmful substance (toxin) released by certain bacteria. The toxoid in vaccines is changed so it does not harm the person, but still produces an immune response.
• Bacterial or viral components are not the whole organism, but only parts of the microbe that trigger a strong immune response.

The harmless infectious component in the vaccine teaches the immune system to recognize the full-strength, live, and harmful substance or organism. The immune system than knows to attack it real exposure occurs. The antibodies produced in response to the vaccine remain in the body, preventing future illness from such an exposure. This is called immunity.

Combination Vaccines. The American Academy of Pediatrics and American Academy of Family Physicians recommend that health care providers use, whenever possible, combination vaccines instead of individual components. Combination vaccines for diphtheria, tetanus, and pertussis (DTaP), and for measles, mumps, and rubella (MMR), have been available for years. New combinations that cover up to 5 vaccinations are being developed and are proving to be safe and well tolerated in infants as young as 2 months. For example, one that combines DTaP, hepatitis B, and the polio vaccine (Pediarix) has been approved in 2002. It is as effective as the individual vaccines when given to children ages 6 weeks to 6 years.

There is some concern that increasing use of combinations may reduce the potency of some of the vaccines. Some parents are also worried about increased side effects. Studies to date, however, are reporting that combinations are effective and safe.

Passive Immunity. Another form of protection against disease is called passive immunity. This approach uses immune globulin, which are blood products containing antibodies. Immune globulin is generally used for people who cannot be vaccinated, when immediate protection is required, or to prevent severe complications of the disease. In some circumstances, passive immunity can interfere with active vaccinations, particularly live-virus vaccines. Therefore, if possible, these two immunization types should not be administered within weeks or even months of each other.

General Information on Side Effects. Vaccines can have side effects, which are nearly always mild, such as swelling at the injection site or fever. There have been a number of reports in the popular press about alarming side effects in many vaccines. Anti-vaccine groups vocally oppose immunizations in children. Although it is true that no vaccine is 100% safe, childhood infections have not been wiped out. Without immunization, parents risk exposing their children to diseases that in the past have killed millions of young children.

General Guidelines

Routine Childhood Vaccines. Experts recommend that all children be routinely vaccinated against the following diseases:

• Measles
• Mumps
• Rubella (German measles)
• Diphtheria
• Tetanus
• Pertussis (whooping cough)
• Poliomyelitis (polio)
• Varicella (chickenpox)
• Hepatitis B
• Hepatitis A
• H. influenzae type b (a cause of meningitis)
• Influenza (children aged 6 months to 18 years)
• Pneumococcal disease
• Meningococcal disease (recommended for all children ages 11 and up; recommended for high-risk children 2-10 years of age).
• Rotavirus (children aged 6 - 32 weeks)

Many vaccinations are first given during infancy. Even premature infants can, in most cases, be given vaccinations on a normal schedule. Note: These facts pertain to children in the United States. Children from other countries have not been well studied. Parents who adopt internationally may want to have their children's immunity assessed by a physician. Some evidence suggests that their medical records may not correctly reflect immunization status and that many adopted children, such as those from China, have not had many important vaccinations.

Common Adolescent and Adult Vaccines. Vaccinations against the following disorders are also recommended routinely for certain adults More information on these vaccines is discussed in the Specific Vaccinations section:

• Influenza (flu) (highly encouraged for all adults)
• Pneumococcal pneumonia.
• Hepatitis A and B and Meningococcal vaccine.
• Tetanus diphtheria and pertussis.
• Measles, mumps, rubella.
• Herpes zoster (shingles) vaccine
• Human papillomavirus (HPV)
• Varicella (chickenpox)

Special Note on Thimerosal

Thimerosal is a preservative that has been used in many vaccines since the 1930s. (Preservatives are necessary to prevent vaccine contamination with live organism in vials that are used for vaccinating multiple people.) Thimerosal contains nearly 50% mercury by weight, but the amount of mercury thimerosal introduced into vaccines has been very small (approximately 25 micrograms of mercury per 0.5 mL dose, according to the Food and Drug Administration). Some people are concerned about possible neurologic consequences from cumulative doses of mercury contained in vaccines given to infants.

In 2004, the Institute of Medicine (IOM) Safety Review Committee reported the results of studies in the U.S. and several European countries evaluating a possible association between thimerosal and autism. They concluded that scientific studies did not find that thimerosal caused autism.

Currently,, all vaccines recommended for children aged 6 or younger contain either no thimerosal or only trace amounts of it, with the exception of the inactivated influenza vaccine. (A limited supply of this vaccine, containing only trace amounts of thimerosal, is available for use in infants, children, and pregnant women.) A trace amount means that a given dose of vaccine contains less than 1 part per million.

Vaccination Recommendations During Pregnancy

Inactivated-virus and toxoid vaccines are usually safe in pregnant women, although any vaccination should be delayed, if possible, until the second or third trimester. Because of a possible risk to the fetus, live-virus vaccines should not be given to pregnant women or those likely to become pregnant within 28 days unless such women need immediate protection against life-threatening diseases, such as yellow fever, that are only prevented using live-virus vaccines. The live-virus MMR combination, which vaccinates against measles, mumps, and rubella, is not given to pregnant women because of the theoretical risk of the live-rubella vaccine to the fetus.

Vaccination Recommendations for People with Compromised Immune Systems

In general, vaccines are not completely effective for patients whose immune systems are compromised by disease or medications. Often, such patients are given immune globulin if they are exposed to infection. It may take 3 months to 1 year before a person who has stopped taking immunosuppressant drugs regains the full ability to be successfully immunized against disease.

Live-virus vaccines are not usually given to people whose immune system has been compromised by illness or by the use of medications.

People who should not get live-virus vaccinations include:

• Persons who have immune deficiency diseases (such as HIV or AIDS).
• Patients with active leukemia or lymphoma.
• Patients who are taking treatments that suppress the immune system, such as corticosteroids, alkylating drugs, antimetabolites, or radiation. (There are important exceptions, however, which are noted in the discussion of individual vaccinations below.) Short-term corticosteroids (given for less than 2 weeks) should not affect any live-virus vaccination. Patients who need vaccinations and who take long-term or high-dose topical steroids should check with their physicians.

Side Effects and Anti-Immunization Groups

Of great concern are anti-immunization organizations and web sites, which were formed mostly because of unsubstantiated reports linking small numbers of serious problems to some vaccines. The following watchdog systems are now in effect to monitor side effects from vaccination:

• VAERS (Vaccine Adverse Event Reporting System) is a government service that registers all adverse events reported after vaccination, including those not related to the vaccine. It is useful for surveillance but has limitations. For example, the service may record the same case more than once. In addition, more serious events that occur after a vaccination are more likely to be reported than later and milder events, and such events are not necessarily linked to the vaccine.
• VSD (Vaccine Safety Datalink) is a linked database that analyzes the records of more than 5 million patients each year. It is more accurate than VAERS, although the information it contains is not as timely.
• The CDC has established the national network of Clinical Immunization Safety Assessment (CISA) Centers. It will provide services to physicians to help them evaluate and manage patients who may have had a side effect.

Studies using these systems are ongoing and none to date have confirmed reports of any significant association between most vaccines and severe side effects that would outweigh the benefits of these important and lifesaving agents.

No vaccine is 100% safe. Allergic and serious reactions are possible. In 2 cases, the early polio vaccine and the first rotavirus vaccine, problems did occur, and some were serious. It is important to note, however, that even in these cases, the vaccines were withdrawn and the severe events were still far fewer than the number of lives saved. Both of these vaccines have been changed and are now safe.

The focus on vaccination side effects is ironic due to the fact that reports of such adverse effects outnumber actual infections. In general, those who do not receive vaccinations are at a higher risk for infection from the illness the vaccine protects from. Because vaccinations have been in existence for so long, today's parents have no direct knowledge of the consequences of these dreaded infections, which killed or severely sickened millions of children in the past.

Tips for Helping Small Children Before, During, and After Vaccinations

Infants often accept the first injection easily, since they are not expecting it. It gets more difficult, however, with each additional injection. Simply providing love and warmth can help children of all ages tolerate immunizations.

Additional tips:

• Do not lie and tell an older child that an injection will be painless. Some health care providers suggest telling your child that it stings a little, and to count to 5 while the vaccine is being administered.
• Ask the doctor if it is OK to give the child a dose of acetaminophen (Tylenol) before or after a vaccination. Ibuprofen (Motrin, Advil) or other non-aspirin pain relievers may be acceptable alternatives. (Children should NEVER take aspirin.)
• A cooling spray may work by numbing the skin a little.
• Longer needles, rather than shorter ones, may help reduce pain.
• Have your child take a deep breath right before the injection and blow out very hard while it is being given. One study reported very good results with this breathing technique.
• Give a sweet fluid before the shot and a little reward, such as a lollipop, immediately after the shot. Sugar actually has mild pain relieving properties for infants.