According to Plotkin and Plotkin (1994), “The impact of vaccination on the health of the world’s people is hard to exaggerate. With the exception of safe water, no other modality, not even antibiotics, has had such a major effect on mortality reduction and population growth” (p. 1). The immunization of children is the responsibility of each primary care provider. Barriers such as the lack of reliable tracking systems, missed opportunities, failure to provide simultaneous immunizations, and administrative or procedural policies against immunizations during certain types of visits still leave some children without adequate coverage. Using each patient encounter as an opportunity to assess immunization status and to administer all appropriate immunizations will continue to improve the rate of immunization coverage.

The recent focus on immunization practices stemmed from the measles outbreak of 1989 to 1991, which was responsible for more than 43,000 reported cases and over 130 deaths (The National Advisory Committee, 1991). Between 1985 and 1989, only 8% of children younger than 4 years had received the measles vaccine. Of these children, 40% were older than 15 months, the recommended age for measles vaccination, and thus should have been immunized. Measles, mumps, rubella (MMR) vaccine protects 95% of people who receive it; therefore, the 1989 measles epidemic resulted from a lack of immunization, not from poor efficacy of the vaccine itself (Orenstein, Atkinson, Mason, & Bernier, 1990; The National Advisory Committee, 1991). This outbreak led to an evaluation of general immunization policies for preschool children and ultimately to a reconsideration of the schedule for MMR administration and the development of the Standards for Pediatric Immunization Practices (Display 13-1). These standards reflect the immunization practice guidelines developed and recommended by the National Vaccine Advisory Committee, approved by the United States Public Health Service, and endorsed by the American Academy of Pediatrics (AAP). Unfortunately, not all providers are familiar with or adhere to these standards. A complete discussion of each standard can be found in the Red Book: Report of the Committee on Infectious Diseases, 24th edition (AAP, 1997).

The goal of immunization is to prevent and ultimately to eradicate disease. This goal is slowly being achieved, as evidenced by the global eradication of smallpox in 1977 and the elimination of poliomyelitis in the Americas in 1991. The incidences of other diseases, such as tetanus, diphtheria, measles, mumps, pertussis, rubella, and Haemophilus influenzae type B (HiB), have been sharply reduced (AAP, 1997). In 1994, an international commission declared wild type polio to be eliminated from the western hemisphere, with the last reported case in 1991 (AAP, 1997; Rodewald, 1999).

These successes are partly due to the increasing adherence of pediatric providers to the Standards for Immunization and an increased focus on the benefits and cost effectiveness of immunizations, resulting in record high coverage levels. Currently, 30 vaccines are licensed in the United States (Table 13-1). Many more are in various stages of research and development, such as vaccines to protect against respiratory syncytial virus, Lyme disease, and herpes.

In 1996, the United States met the goal of 90% immunization coverage adopted by Healthy People 2000, using the 4:3:1 criteria (four or more doses of diphtheria, tetanus, and pertussis; three or more doses of polio; and one or more doses of measles vaccine). When three doses of HiB are added (4:3:1:3), the rate of coverage falls to 76% as estimated by the National Immunization Survey in conjunction with the Centers for Disease Control and Prevention (CDC) (Altemeier, 1998). These data contrast sharply with earlier literature showing the United States lagging behind many European and developing countries in rates of immunization coverage for preschool children (Guyer & Hughart, 1994; Altemeier, 1998). Varicella coverage in 1997 was estimated to be 25%, up from 19% in 1996.

Active immunization is defined as administration of all or part of a microorganism or modified product of that microorganism (such as a toxoid, purified antigen, or genetically engineered antigen) that invokes an immunologic response mimicking the natural infection (AAP, 1997). Usually this procedure poses little or no risk to the patient. Some vaccines provide complete protection throughout life with only one dose; others require multiple doses or boosters. Vaccines composed of an intact (whole) infectious agent are either live-attenuated or killed (inactivated). Many viral vaccines are live-attenuated preparations, where the infectious agent replicates but causes little or no adverse host reaction. Live-attenuated vaccines generally provide a wider range of immunologic response than killed preparations. Most bacterial and some viral vaccines are inactivated; therefore, the infectious agent does not replicate within the host. This type of vaccine often requires a booster. One advantage of this type of vaccine is that the infectious agent is not replicated and therefore not excreted by the patient. Thus, such a vaccine does not adversely affect immunocompromised patients or caregivers. Combination vaccines contain multiple killed or attenuated organisms and provide protection from disease with fewer injections. A well-known example is the diphtheria-tetanus-pertussis (DTP) vaccine.

Bacterial conjugate vaccines link a polysaccharide capsule to a carrier protein directly or using a spacer molecule. Protective
antibody responses are directed against the specific polysaccharide capsule chosen, such as Hib. The goal of bacterial conjugate vaccines is to provoke a host antibody response to bacteria, such as gram-negative bacteria with polysaccharide capsules, which normally do not elicit a strong response in immunologically immature individuals (eg, those younger than 2 years). Obviously, these vaccines are targeted for this vulnerable age group; therefore, the use of a more immunogenic bacterial conjugate confers protection against these organisms even in very young children. Common examples are Hib and pneumococcal vaccines. Bacterial conjugate vaccines differ in composition and immunogenicity and therefore in recommendations for their use.

All vaccine preparations contain an active immunizing antigen and a fluid for the suspension of this antigen, such as sterile water, saline, or tissue culture fluids containing proteins such as eggs or gelatin. Vaccines also contain stabilizers or preservatives (including antibiotics) and occasionally adjuvants (most commonly an aluminum salt) to enhance immunogenicity. All the above may cause allergic responses in susceptible individuals.

Some vaccines require reconstitution. Reconstituting vaccines ahead of time should be discouraged, because doing so may alter their potency or effectiveness.

Vaccines can be administered orally or parenterally (intramuscularly or subcutaneously). The intramuscular site chosen depends on the volume of injected material and the size of the muscle. Generally, the anterolateral muscle of the thigh is chosen for the child younger than 1 year and the deltoid muscle for older children. Most parents feel that use of the deltoid muscle as opposed to the anterolateral thigh muscle reduces discomfort and distress in ambulatory children. Parents should be present to comfort the child during administration, and the child should be securely restrained during the actual delivery to avoid injury caused by grabbing at the needle or from a sudden unexpected movement.

Prior to administering any vaccine, the provider must inquire about adverse effects from previous immunizations. The provider also has a duty to warn the parent or guardian about the possible risks and benefits of vaccination. A duty is not the same as informed consent; rather, it is a federal requirement stemming from the National Childhood Vaccine Injury Act of 1986. This act requires health care providers to maintain permanent vaccination records and to report adverse events that follow immunization.

Since 1994, the federal government requires all health care providers who administer any vaccine containing diphtheria, tetanus, pertussis, measles, mumps, rubella, polio, varicella, hepatitis B, or Hib vaccine to provide a copy of the relevant vaccine information materials to the legal representative of any child prior to administration. These materials must be supplemented with visual presentations or oral explanations in appropriate cases. These vaccine information sheets are available through state health departments and the CDC as well as online at http://www.cdc.gov/nip. The provider’s responsibility is to provide copies of informational material, discuss the information, answer questions, respond to concerns, and then document parental decisions. Some practices require a parent’s or guardian’s signature to refuse and to accept vaccinations because of lawsuits involving failure to vaccinate when a person acquires a disease preventable by vaccine (Rodewald, 1999).

The religious beliefs and philosophical practices of parents must be respected, but clinicians can assist parents to make informed decisions by providing information and allowing ample time to answer questions. The benefits of immunization to their child and any children who come in contact with that child should be strongly emphasized. Children who are unable to receive immunizations must rely on the immunization
status of others to prevent exposure to disease. This concept has been referred to as herd immunity. Ultimately, most states will allow exemptions from required school entry immunizations for religious or philosophical beliefs; however, each provider has the responsibility to ensure that parents receive all necessary information to make informed choices regarding immunizations for their children.

All vaccines are refrigerated or frozen. Storage procedures for vaccines vary but are extremely important to maintain the effectiveness of a product. Improper storage may render a vaccine ineffective. Providers should follow the manufacturer’s
guidelines closely regarding storage requirements for each vaccine.